@article {45361, title = { One pot ligand exchange method for a highly stable Au-SBA-15 catalyst and its room temperature CO oxidation}, journal = {Chemical Communications}, volume = {54}, year = {2018}, month = {NOV}, pages = {12412-12415}, type = {Article}, abstract = {A modified deposition precipitation (DP) method has been developed to address a fundamental issue of supporting well dispersed Au nanoparticles on silica. Ammonium chloride (NH4Cl) plays an important role in in situ modifying the gold precursor (HAuCl(4)3H(2)O) solution allowing facile deposition of gold NPs in the channels of SBA-15. The Au-SBA-15 catalyst (2.8 wt\%) synthesized by this procedure showed 100\% conversion for CO oxidation at room temperature with excellent stability at room temperature and high temperature.}, issn = {1359-7345}, doi = {10.1039/c8cc06887a}, author = {Soni, Yogita and Kavya, I. and Ajithkumar, T. G. and Vinod, C. P.} } @article {44553, title = {Preparation of colourless phosphate glass by stabilising higher Fe[II] in microwave heating}, journal = {Scientific Reports}, volume = {8}, year = {2018}, month = {APR}, pages = {6195}, abstract = {

Iron impurity in raw material remains a major challenge in producing colourless glass. In this investigation, we report microwave (MW) heating capable of altering Fe-redox ratio (Fe2+/Sigma Fe) enabling preparation of colourless phosphate glass. The effect of Sn concentration in retention of Fe[II] in glass melted in MW was compared with conventional glasses. Colourimetric study developing Fe2+-ferrozine colour complex reveals Fe-redox ratio \>= 0.49 required to obtain colourless phosphate glass. In microwave heating, addition of 1 wt.\% Sn metal powder can impart the desired effect whereas addition of 1.9 wt.\% Sn metal powder is required in conventional heating. The correlation equation of Fe-redox ratio with concentration of Sn metal is found to be different in microwave and conventional heating. Thus, exploiting this different redox changes in MW heating optical properties can be tailored. Preservation of higher Fe[II] in MW melted glass is also confirmed by XPS and TGA. P-31 MAS NMR spectra suggest that transition from cross linked ultra phosphate to linear polymer metaphosphate network in incorporation of Sn is found different in glass prepared adopting microwave irradiation. (27)A1 MAS NMR spectra suggest higher relative content of Al6+ in glass obtained from MW heating. Energy consumption analysis revels 3.4 kWh in MW heating while 14 kWh in conventional glass melting using resistance heating. Further, glass melting in MW can be completed within 2 h unlike similar to 5 h needed in conventional. MW heating plays a significant role in improving properties to make colourless phosphate glass in addition to significant energy and time saving.

}, issn = {2045-2322}, doi = {10.1038/s41598-018-24287-1}, author = {Mandal, Ashis K. and Mandal, B. and Illath, Kavya and Ajithkumar, T. G. and Halder, A. and Sinha, P. K. and Sen, Ranjan} } @article {44564, title = {Structural elucidation of NASICON (Na3Al2P3O12) based glass electrolyte materials: effective influence of boron and gallium}, journal = {RSC Advances}, volume = {8}, year = {2018}, pages = {14422-14433}, type = {Journal Article}, abstract = {

Understanding the conductivity variations induced by compositional changes in sodium super ionic conducting (NASICON) glass materials is highly relevant for applications such as solid electrolytes for sodium (Na) ion batteries. In the research reported in this paper, NASICON-based NCAP glass (Na2.8Ca0.1Al2P3O12) was selected as the parent glass. The present study demonstrates the changes in the Na+ ion conductivity of NCAP bulk glass with the substitution of boron (NCABP: Na2.8Ca0.1Al2B0.5P2.7O12) and gallium (NCAGP: Na2.8Ca0.1Al2Ga0.5P2.7O12) for phosphorus and the resulting structural variations found in the glass network. For a detailed structural analysis of NCAP, NCABP and NCAGP glasses, micro-Raman and magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopic techniques (for 31P, 27Al, 23Na, 11B and 71Ga nuclei) were used. The Raman spectrum revealed that the NCAP glass structure is more analogous to the AlPO4 mesoporous glass structure. The 31P MAS-NMR spectrum illustrated that the NCAP glass structure consists of a high concentration of Q0 (3Al) units, followed by Q0 (2Al) units. The 27Al MAS-NMR spectrum indicates that alumina exists at five different sites, which include AlO4 units surrounded by AlO6 units, Al(OP)4, Al(OP)5, Al(OAl)6 and Al(OP)6, in the NCAP glass structure. The 31P, 27Al and 11B MAS-NMR spectra of the NCABP glass revealed the absence of B{\textendash}O{\textendash}Al linkages and the presence of B3{\textendash}O{\textendash}B4{\textendash}O{\textendash}P4 linkages which further leads to the formation of borate and borophosphate domains. The 71Ga MAS-NMR spectrum suggests that gallium cations in the NCAGP glass compete with the alumina cations and occupy four (GaO4), five (GaO5) and six (GaO6) coordinated sites. The Raman spectrum of NCAGP glass indicates that sodium cations have also been substituted by gallium cations in the NCAP glass structure. From impedance analysis, the dc conductivity of the NCAP glass (\~{}3.13 {\texttimes} 10-8 S cm-1) is slightly decreased with the substitution of gallium (\~{}2.27 {\texttimes} 10-8 S cm-1) but considerably decreased with the substitution of boron (\~{}1.46 {\texttimes} 10-8 S cm-1). The variation in the conductivity values are described based on the structural changes of NCAP glass with the substitution of gallium and boron.

}, issn = {20462069}, doi = {10.1039/C8RA01676C}, author = {Allu, Amarnath R.}, editor = {Balaji, Sathravada} } @article {46236, title = {Raman and Na-23 solid-state NMR studies on the lead-free ferroelectrics Bi-0.5(Na1-xKx)(0.5)TiO3 in the morphotropic phase boundary region}, journal = {Materials Research Bulletin}, volume = {118}, year = {2019}, month = {OCT}, type = {Article}, abstract = {

The local structural changes, due to the substitution of the smaller Na+ by the larger K+ ion, in the lead-free piezoelectric ceramic compositions Bi-0.5(Na1-xKx)(0.5)TiO3 have been studied using Raman and Na-23 solid-state NMR spectroscopy. Different close compositions in the solid solution series Bi-0.5(Na1-xKx)(0.5)TiO3 (0 \<= x \<= 0.36, Delta x = 0.02) are studied in the morphotropic phase boundary (MPB) region arising from the different crystal structures of the end members Bi0.5Na0.5TiO3 and Bi0.5K0.5TiO3. Close correlations between the Raman and NMR parameters with the performance parameters of the system have been observed, suggesting the role of the local structural changes in determining these parameters. Raman and Na-23 NMR studies showed that the onset of the MPB region is at x = 0.16 and the MPB region corresponds to 0.16 \<= x \<= 0.24 where better performance parameters are observed.

}, doi = {10.1016/j.materresbull.2019.110506}, author = {Anjali, K. and Ajithkumar, T. G. and Joy, P. A.} } @article {46923, title = {Dynamics in amine-functionalized mesoporous hybrid materials probed through deuterium magic angle spinning NMR and molecular dynamic simulations}, journal = {Journal of Physical Chemistry C}, volume = {124}, year = {2020}, month = {MAR}, pages = {6154-6170}, type = {Article}, abstract = {

We present a deuterium magic angle spinning (MAS) NMR study on two widely used hybrid materials (3-glycidyloxy propyl)trimethoxysilane (3-GPTMS) and 3-(trimethoxysilyl)propyl methacrylate (3-MATMS) grafted on SBA-15. Methylene-deuterated diamine as a pendent group is anchored to GPTMS (O3Si-CH2-CH2-CH2-O-CH2-CH(OH)- CH2-NH-CD2-CD2-NH2) and MATMS (O3Si-CH2-CH2-CH2-O-C(N-CD2-CD2-NH2)-C(CH3)=-CH2) postgrafting. Proton and deuterium solid state NMR experiments under MAS were performed at two hydration levels and temperatures ranging from 253 to 315 K. Deuterium spectra were deconvoluted into three A Dr, components with different average quadrupolar parameters: a relatively rigid component arising from local or librational motion of C-H-2(2) corresponding to {\textquoteleft}{\textquoteleft}small angle{\textquoteright}{\textquoteright} jumps, an intermediate dynamic component, and a large amplitude dynamic component. Population ratios of rigid versus dynamic components show that diamine-MATMS is more rigid when compared with diamine-GPTMS at high hydration. The role of the length of the linkers, steric hindrance, grafting concentration, etc. in defining mobility is investigated. Finally, by correlating proton and deuterium MAS NMR spectral analysis, the role of a few water molecules in inducing dynamics of the linkers was investigated. Molecular dynamic (MD) simulations support the experimental analysis. MD simulations indicate different types of mobility arising from the same molecular binding configuration of diamine-MATMS. Dynamics induced by a few hydroxyls on the pore surface accessible to the linker, various molecular conformations, and stabilization of the linker through hydrogen bonding with the surface, derived from MD simulations, are discussed.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.9b11948}, author = {Veena, V. S. and Kavya, I and Lazar, A. and Vinod, C. P. and Ajithkumar, T. G. and Jayanthi, S.} } @article {46747, title = {Elucidating the effect of CaF 2 on structure, biocompatibility and antibacterial properties of S53P4 glass}, journal = {Journal of Alloys and Compounds}, volume = {831}, year = {2020}, month = {AUG }, pages = {154704}, type = {Article}, abstract = {

The present work focuses on the synthesis and structural elucidation of fluoride containing bioactive glasses in the system (in mol\%) given by (53.86) SiO2\ {\textendash} (22.65) Na2O {\textendash} (21.77-x) CaO {\textendash} (1.72) P2O5\ {\textendash} x CaF2, where, x\ =\ 0, 5.44, 10.885 and 16.33. The role of the incorporated fluoride and its distribution within the glass were interpreted and analyzed using Molecular dynamics (MD) simulations and the results were compared with the modified random network (MRN) model. The interpretations from the model have been verified using the MAS-NMR spectroscopy technique. According to this model, fluoride containing bioactive glasses have been proposed to consist of silicate rich network regions and modifier cation {\textendash} fluoride rich inter-network regions. The interface region was found to consist of non-bridging oxygen species (NBO) and phosphate cations which are either isolated orthophosphates (Q0P) or bridged with silicates in the form of pyrophosphate (Q1P) units forming Si{\textendash}O{\textendash}P bonds. The gradual substitution of CaF2\ for CaO in the base glass resulted in an increase in the silicate network connectivity with a reduction in the NBOs and lead to an increase in the association of modifier cations with fluoride ions. However, fluoride ions were found to show a marginal preference to associate with Na+\ cations leading to a decrease in the association of Na+\ ions with orthophosphate and silicate units. These overall structural findings were correlated with the\ in\ vitro\ ion dissolution behaviour of the bioactive glasses as well as with the thermal properties. The glasses were tested for their\ in\ vitro\ cell viability towards mouse osteoblast type (MC3T3) cells in which fluoride containing bioactive glasses did not show any toxicity and exhibited better cell proliferation. The antibacterial efficacy of the fluoride containing glasses was tested at various concentrations (5, 10 and 20\ mg/ml) in\ E.coli\ bacterial inoculum in which bactericidal action was evidenced.

}, keywords = {Fluoride bioactive glasses, In~vitro apatite formation and bactericidal action, MAS-NMR spectroscopy, MD simulations}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2020.154704}, author = {Prasad, Sakthi and Ganisetti, Sudheer and Jana, Anuradha and Kant, Shashi and Sinha, P. K. and Tripathy, Sucheta and Illath, Kavya and Ajithkumar, T. G. and Annapurna, K. and Allu, Amarnath R. and Biswas, Kaushik} } @article {46940, title = {FeNx/FeSx-anchored carbon sheet-carbon nanotube composite electrocatalysts for oxygen reduction}, journal = {ACS Applied Nano Materials}, volume = {3}, year = {2020}, month = {MAR}, pages = {2234-2245}, type = {Article}, abstract = {

Even though various Pt-free electrocatalysts for oxygen reduction reaction (ORR) have been introduced, many of them are found to be active only in alkaline conditions. Considering Nafion, phosphoric acid-doped polybenzimidazole (PBI), and so on as the prominent ionomer membranes, used in the commercially available polymer electrolyte membrane fuel cells (PEMFCs), it becomes important that any development on the Pt-free catalysts should ensure the better ORR performance under acidic conditions. The present work effectively tackles this issue, where an ORR-based catalyst could be prepared with simultaneous incorporation of both Fe-N and Fe-S active sites on in situ generated carbon sheets which are spatially separated by the carbon nanotube (CNT) network. This catalyst shows ability to perform under both acidic and basic conditions. This has been achieved by growing a polyethylenedioxythiophene polymer network in the presence of CNT and melamine followed by its pyrolysis under an inert atmosphere. The catalyst formed at 900 degrees C (PMCNT-900) displays 0.94 V onset potential for ORR under acidic electrolyte conditions, which corresponds to 60 mV overpotential compared to its 40 wt \% Pt/C counterpart. Interestingly, in single cell demonstration of Nafion-based PEMFC with PMCNT-900 as the cathode catalyst, the system delivered a maximum power density (PD) of 500 and 275 mW/cm(2) at 60 degrees C under H-2-O-2 and H-2-air feed conditions, respectively. On the other hand, in a single cell test in the anion exchange membrane fuel cell (AEMFC) mode, a maximum power density of 65 mW/cm(2) at 50 degrees C could be achieved with the same cathode catalyst, which is a comparable value obtained while employing Pt/C as the cathode. These results, thus, infer to the efficiency of the catalyst to facilitate ORR under the extreme pH conditions, and particularly its performance under acidic condition reveals its prospect as a potential Pt-free electrocatalyst to serve in the Nafion-based systems.

}, keywords = {carbon nanotube, electrocatalyst, fuel cell, oxygen reduction reaction, Pt-free ORR}, issn = {2574-0970}, doi = {10.1021/acsanm.9b02335}, author = {Bhange, Siddheshwar N. and Soni, Roby and Singla, Gourav and Ajithkumar, T. G. and Kurungot, Sreekumar} } @article {46702, title = {Photocatalytic hydrogen generation and CO2 conversion using g-C3N4 decorated dendritic fibrous nanosilica: role of interfaces between silica and g-C3N4}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {SEP }, pages = {8150-8158}, type = {Article}, abstract = {

We have synthesized g-C3N4 decorated over dendritic fibrous nanosilica (DFNS). The generation of C-N-Si interfaces by coating each fiber of DFNS with g-C3N4 not only provided high surface area but also affected the optical and electronic properties of the composite. The catalyst synthesis reproducibility issue of g-C3N4 was resolved using a vacuum-sealed quartz tube. The extended light absorption in the visible region, enhanced lifetime of photogenerated charge carriers due to the formation of interfaces between silica and g-C3N4 (confirmed by solid-state NMR), and increased surface area result in the improved photocatalytic activity of DFNS/g-C(3)N(4)for hydrogen generation and CO2 conversion.

}, keywords = {CO2 conversion, DFNS, g-C3N4, Hydrogen generation, nanocatalysts, photocatalysts, Solid-state NMR}, issn = {2574-0962}, doi = {10.1021/acsaem.0c01265}, author = {Rawool, Sushma A. and Samanta, Anupam and Ajithkumar, T. G. and Kar, Yusuf and Polshettiwar, Vivek} } @article {47736, title = {Elucidating the effect of CaF2 on structure, biocompatibility and antibacterial properties of S53P4 glass (vol 831, 154704, 2020)}, journal = {Journal of Alloys and Compounds}, volume = {883}, year = {2021}, month = {NOV}, pages = {161253}, type = {Correction}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2021.161253}, author = {Prasad, Sakthi and Ganisetti, Sudheer and Jana, Anuradha and Kant, Shashi and Sinha, P. K. and Tripathy, Sucheta and Illath, Kavya and Ajithkumar, T. G. and Annapurna, K. and Allu, Amarnath R. and Biswas, Kaushik} } @article {47031, title = {Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application}, journal = {Journal of Non-Crystalline Solids}, volume = {558}, year = {2021}, month = {APR }, pages = {120654}, type = {Article}, abstract = {

Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly (vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt\% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49 +/- 0.31) x 10(-3)Scm(-1) and (2.70 +/- 0.04) x 10(-4)Scm(-1), respectively. The thermal stability of the prepared CSE is tested upto 315 degrees C without any degradation. Two cells (Cell-I \& Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg1 at 50th cycle which is higher as compared to Cell-I (129mAhg(-1)) when tested at the C-rate of 0.05 degrees C.

}, keywords = {Lithium germanium phosphate, NASICON, Solid state electrolyte, Solid state NMR}, issn = {0022-3093}, doi = {10.1016/j.jnoncrysol.2021.120654}, author = {Das, Anurup and Goswami, Madhumita and Illath, Kavya and Ajithkumar, T. G. and Arya, A. and Krishnan, M.} } @article {48231, title = {Effect of oxalic acid and sulphuric acid hydrolysis on the preparation and properties of pineapple pomace derived cellulose nanofibers and nanopapers}, journal = {International Journal of Biological Macromolecules}, volume = {209}, year = {2022}, month = {JUN }, pages = {1745-1759}, type = {Article}, abstract = {

Nanocellulose is the {\textquoteleft}{\textquoteleft}green magnet{\textquoteright}{\textquoteright} which attracts a wide spectrum of industries towards it due to its availability, biodegradability, and possible smart applications. For the first time, pineapple pomace was being explored as an economic precursor for cellulose nanofibers. Nanofiber isolation was accomplished using a chemo-mechanical method and solution casting was adopted for the development of nanopapers. Moreover, the study examines the structural, optical, crystalline, dimensional, and thermal features of nanofibers isolated using different acid hydrolysis (oxalic acid and sulphuric acid) methods. Fourier-transform infra-red spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, and X-ray diffraction analysis indicated the presence of type I cellulose. The transmittance, crystallinity index, and thermal stability of PPNFS (sulphuric acid treated fiber) were greater than PPNFO (oxalic acid treated fiber). The transmission electron microscopy and dynamic light scattering analysis confirmed the nanodimension of PPNFO and PPNFS. While comparing the optical and mechanical properties of nanopapers, PPNFS outperforms PPNFO. The tensile strength of the prepared nanopapers (64 MPa (PPNFO) and 68 MPa (PPNFS)) was found to be high compared to similar works reported in the literature. The prepared nanopaper is proposed to be used for food packaging applications.

}, keywords = {cellulose nanofibers, Cellulosic nanopapers, Pineapple pomace}, issn = {0141-8130}, doi = {10.1016/j.ijbiomac.2022.04.138}, author = {Neenu, K. V. and Dominic, C. D. Midhun and Begum, P. M. Sabura and Parameswaranpillai, Jyotishkumar and Kanoth, Bipinbal Parambath and David, Deepthi Anna and Sajadi, S. Mohammad and Dhanyasree, P. and Ajithkumar, T. G. and Badawi, Michael} } @article {47719, title = {The effects of cis and trans butenedioic acid on the physicochemical behavior of lumefantrine}, journal = {Crystengcomm}, volume = {24}, year = {2022}, month = {JAN }, pages = {156-168}, type = {Article}, abstract = {The present work investigates the effects of cis and trans butenedioic acid isomers (maleic acid and fumaric acid) on the crystallinity and pharmaceutical behavior of lumefantrine. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), attenuated total reflectance infrared spectroscopy (ATR-IR), solid-state nuclear magnetic resonance spectroscopy (ss-NMR), and single-crystal X-ray diffraction (SC-XRD) studies were employed. Lumefantrine-fumaric acid crystallized as a salt in the monoclinic space group P2(1)/c. In comparison, DSC and PXRD showed the formation of a co-amorphous solid with maleic acid. Complete proton transfer with a strong ionic interaction led to crystalline salt formation with the trans isomer, whereas weaker/fewer hydrogen bonds with the cis isomer of butenedioic acid led to a co-amorphous salt. The in vitro dissolution of both salts resulted in a similar 2.6-2.7-fold improvement in dissolution rate when compared to that of the crystalline lumefantrine. The crystalline and co-amorphous salts were stable under accelerated stability conditions (40 +/- 2 degrees C and 75 +/- 5\% RH) for one month.}, doi = {10.1039/d0ce01709d}, author = {Tomar, Devendrasingh and Lodagekar, Anurag and Gunnam, Anilkumar and Allu, Suryanarayana and Chavan, Rahul B. and Tharkar, Minakshi and Ajithkumar, T. G. and Nangia, Ashwini K. and Shastri, Nalini R.} } @article {48471, title = {Investigation of Al2O3 induced variations in the structural parameters in strontium borosilicate glasses using solid state NMR}, journal = {Physical Chemistry Chemical Physics}, volume = {25}, year = {2023}, month = {MAY }, pages = {13550-13559}, type = {Article}, abstract = {

The physical properties of oxide glasses are crucially dependent on the atomistic structural speciation. In this study, we investigate the variation in the local ordering in the glass network of strontium borosilicate glasses (34.82 SrO, 51.84 B2O3, 13.34 SiO2 in mol\%) with a progressive substitution of B2O3 by Al2O3 and estimate the structural parameters: the oxygen packing fraction, and the average network coordination number. The coordination of the network forming cations at various glass compositions is determined using B-11, Al-27, and Si-29 solid-state nuclear magnetic resonance (SSNMR). The SSNMR reveals that at the higher substitution of B2O3 by Al2O3 in the glass composition, the coordination network of Al3+ exists predominantly in the 4 coordinated state, the network forming B3+ cations transform from a tetrahedral BO4 to a trigonal BO3 structure, and the Q(4) form of silicates is dominant. The average coordination number and the oxygen packing fraction were calculated using the parameters obtained from the SSNMR results, and it is observed that the average coordination number decreases, and the oxygen packing fraction increases on incorporating Al. It is interesting to note that some of the thermophysical properties of these compositions closely follow the pattern shown by the average coordination number and the oxygen packing fraction.

}, issn = {1463-9076}, doi = {10.1039/d3cp00751k}, author = {Illath, Kavya and Ojha, Prasanta K. and Rath, Sangram K. and Ajithkumar, T. G.} } @article {48834, title = {Nanosilica from Averrhoa bilimbi juice pre-treated rice husk: preparation and characterization}, journal = {Journal of Cleaner Production}, volume = {413}, year = {2023}, month = {AUG }, pages = {137476}, type = {Article}, abstract = {

The preparation of nanosilica from rice husk without using any concentrated mineral acids is a novel concept. This work proposes a bioleaching strategy to remove metallic impurities from rice husk for the preparation of nanosilica. Herein, nanosilica (BJRHS) was prepared by calcinating Averrhoa bilimbi juice pre-treated rice husks in a muffle furnace. The chemical and atomic structures of commercial precipitated silica (CS), rice husk ash (RHA), and BJRHS were analyzed using different analytical techniques. The optimal leaching time, calcination temperature, and calcination time were 1 h, 500 degrees C, and 6 h respectively. The particle size of BJRHS was found to be 6-12 nm, which is less than that of RHA and CS. The BET surface area of BJRHS (204 m2/g) was found to be greater than RHA (110.5 m2/g) and CS (172.1 m2/g). Mesoporous nanosilica with excellent surface area and purity was produced sustainably from rice husk which could be recommended to use in the field of catalysis, polymer technology, etc.

}, keywords = {Averrhoa bilimbi juice, Bioleaching, Nanosilica, rice husk}, issn = {0959-6526}, doi = {10.1016/j.jclepro.2023.137476}, author = {Dominic, C. D. Midhun and Neenu, K. V. and Begum, P. M. Sabura and Joseph, Rani and Rosa, Derval dos Santos and Duan, Yongxin and Balan, Aiswarya and Ajithkumar, T. G. and Soumya, Mary and Shelke, Ankita and Parameswaranpillai, Jyotishkumar and Badawi, Michael} } @article {49633, title = {Colocasia esculenta stems for the isolation of cellulose nanofibers: a chlorine-free method for the biomass conversion}, journal = {Biomass Conversion and Biorefinery}, volume = {14}, year = {2024}, month = {MAY}, pages = {10305-10318}, type = {Article}, abstract = {

The reuse of waste products is the green key to sustainability. The extraction of cellulose nanofibers from Colocasia esculenta stems is presented in the paper. The study proved that the waste biomass could be effectively re-engineered into highly valued cellulose nanofibers (CNFs). Cellulose nanofibers were extracted via a chemo-mechanical route. The pre-treatments included mild alkali hydrolysis (2\% NaOH) and chlorine-free bleaching (peroxide bleaching in an alkaline medium). Cellulose I-beta structure was confirmed using C-13 solid-state nuclear magnetic resonance spectroscopy and X-ray diffraction analysis. The elemental analysis of CNFs detected the elements, carbon and oxygen. The CNFs had a crystallinity and transmittance of 71.72\% and 60\%, respectively. Microscopic studies verified the elimination of non-cellulosic components and the fibrous nature of CNFs. Moreover, the fiber diameter of CNFs was 20-40 nm. Thermal analysis revealed good thermal stability of 335.8 degrees C (T-50) for nanofibers. Long-term aids are numerous in eco-friendly technology. Developing an eco-design will support zero waste ideals, lowers carbon dioxide emissions, and encourages a circular economy. Owing to the merits of natural fibers, they can be adopted in various sectors including packaging, automobile, aerospace, electronics, biomedical, construction, and furniture.

}, keywords = {acid hydrolysis, cellulose nanofibers, Colocasia esculenta stems, High crystallinity}, issn = {2190-6815}, doi = {10.1007/s13399-022-03171-z}, author = {Dominic, C. D. Midhun and Maheswary, S. and Neenu, V. K. and Sajadi, S. Mohammad and Rosa, Derval dos Santos and Begum, P. M. Sabura and Mathew, Mariya and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and George, Tresa Sunitha and Resmi, V. C. and Ilyas, R. A. and Badawi, Michael} } @article {49064, title = {Extraction, characterization, and life cycle assessment of nanosilica from millet husk: sustainable alternative with low environmental impact}, journal = {Journal of Cleaner Production }, volume = {442}, year = {2024}, month = {FEB}, pages = {140924}, type = {Article}, abstract = {

Eco-friendly approaches for silica production are highly researched to respond increasing industrial demand for bio-nanofillers. Herein, nanosilica of 10-20 nm with mesoporosity was obtained through a mild oxalic acid pre-treatment of millet husk, followed by calcination at 700 degrees C for 2 h. Compared with commercial precipitated silica (CS) and millet husk ash (MHA) directly obtained by calcination of the husk, the pre-treated silica (MHS) had higher purity, revealed using EDX spectroscopy. Moreover, FTIR and Si-29 NMR showed a higher condensation degree in MHS with 73\% of Q4 siloxane bonds vs 4\% in MHA. The release of the metal and organic impurities from the husk also allows to reduce the crystallinity of MHS, and to increase the specific surface area from 82 m(2)/g in MHA to 238 m(2)/g in MHS. The type II N-2 adsorption-desorption isotherms of MHA and MHS indicate aggregates of non-porous silica particles. MHS also demonstrated remarkable thermal resilience. According to the LCA analysis, MHS has a 40\% lower impact on global warming, a 38\% lower impact on human carcinogenic toxicity, and a 38\% lower impact on terrestrial acidification compared to rice husk nanosilica. This research thus addresses sustainability challenges by repurposing millet husks, which are readily available due to continuous millet cultivation, particularly in India. By reducing the ecological impact of husk disposal through burning, this study offers an economically viable technology for high-purity silica production, aligning with global efforts to combat climate change and promote sustainable practices.

}, keywords = {Life cycle assessment, Millet husk, Nanosilica, Oxalic acid}, issn = {0959-6526}, doi = {10.1016/j.jclepro.2024.140924}, author = {Dominic, C. D. Midhun and Rosa, Derval dos Santos and Barbosa, Rennan Felix da Silva and Anagha, O. V. and Neenu, K. V. and Begum, P. M. Sabura and Kumar, V. Aswathy and Parameswaranpillai, Jyotishkumar and Siriwong, Chomsri and Ajithkumar, T. G. and Shelke, Ankita and Pasc, Andreea} } @article {49106, title = {In situ monitoring of competitive coformer exchange reaction by 1H MAS solid-state NMR}, journal = {Molecualr Pharmaceutics}, volume = {21}, year = {2024}, month = {FEB }, pages = {1479-1489}, type = {Article}, abstract = {

In a competitive coformer exchange reaction, a recent topic of interest in pharmaceutical research, the coformer in a pharmaceutical cocrystal is exchanged with another coformer that is expected to form a cocrystal that is more stable. There will be a competition between coformers to form the most stable product through the formation of hydrogen bonds. This will cause destabilization of the pharmaceutical products during processing or storage. Therefore, it is important to develop a mechanistic understanding of this transformation by monitoring each and every step of the reaction, employing a technique such as H-1 nuclear magnetic resonance (NMR). In this study, an in situ monitoring of a coformer exchange reaction is carried out by H-1 magic angle spinning (MAS) solid-state NMR (SSNMR) at a spinning frequency of 60 kHz. The changes in caffeine maleic acid cocrystals on addition of glutaric acid and caffeine glutaric cocrystals on addition of maleic acid were monitored. In all of the reactions, it has been observed that caffeine glutaric acid Form I is formed. When glutaric acid was added to 2:1 caffeine maleic acid, the formation of metastable 1:1 caffeine glutaric acid Form I was observed at the start of the experiment, indicating that the centrifugal pressure is enough for the formation. The difference in the end product of the reactions with a similar reaction pathway of 1:1 and 2:1 reactant stoichiometry indicates that a complete replacement of maleic acid has occurred only in the 1:1 stoichiometry of the reactants. The polymorphic transition of caffeine glutaric acid Form II to Form I at higher temperatures was a crucial reason that triggered the exchange of glutaric acid with maleic acid in the reaction of caffeine glutaric acid and maleic acid. Our results are novel since the new reaction pathways in competitive coformer exchange reactions enabled understanding the remarkable role of stoichiometry, polymorphism, temperature, and centrifugal pressure.

}, keywords = {caffeine cocrystal, coformer exchange reaction, in situ monitoring, polymorphism, Solid-state NMR}, issn = {1543-8384}, doi = {10.1021/acs.molpharmaceut.3c01118}, author = {Hareendran, Chaithanya and Alsirawan, Bashir and Paradkar, Anant and Ajithkumar, T. G.} } @article {49041, title = {Insights into the structure of sucralfate by advanced solid- and liquid-state NMR}, journal = {Molecualr Pharmaceutics }, volume = {21}, year = {2024}, month = {FEB }, pages = {1390-1401}, type = {Article}, abstract = {

Sucralfate, which is a sucrose octasulfate aluminum complex, is an active pharmaceutical ingredient (API) falling in the category of cytoprotective agents which are very effective for gastric and duodenal ulcers. On interaction with stomach acid, it ionizes into aluminum and sucrose octasulfate ions to form a protective layer over the ulcerated region inhibiting further attack from acid. The mechanism of action of sucralfate in the context of its structure is not well understood. Considering that at least two forms of this API are available in the market, there are no reports on the various forms of sucralfate and differences in their pharmacological action. We characterized the two forms of sucralfate using multinuclear, multidimensional solid-state NMR, and the results show significant structural differences between them arising from variation in the aluminum environment and the level of hydration. The impact of structural differences on pharmacological action was examined by studying acid-induced Al release by Al-27 liquid-state NMR. The sucralfate, European pharmaceutical standard, Form I, undergoes faster disruption in acid compared to Form II. The difference is explained on the basis of structural differences in the two forms which gives significant insights into the action of sucralfate in relation to its structure.

}, keywords = {(27)AlMQMAS, H-1-H-1 DQSQ, pharmacological action, solid-stateNMR, sucralfate}, issn = {1543-8384}, doi = {10.1021/acs.molpharmaceut.3c01042}, author = {Hareendran, Chaithanya and Ravindranathan, Sapna and Ajithkumar, T. G.} } @article {49042, title = {Solid-state NMR method for characterization of pharmaceutical eutectics}, journal = {Physical Chemistry Chemical Physics}, volume = {26}, year = {2024}, month = {JAN }, pages = {3800-3803}, type = {Article}, abstract = {

Pharmaceutical eutectics are extremely useful for designing formulations, and currently, there are no techniques other than differential scanning calorimetry (DSC) that can confirm their formation. In this study, we demonstrate that 1H fast magic angle spinning (MAS) solid-state NMR (SSNMR) experiments can confirm the formation of eutectics by detecting their intermolecular hydrogen bonding interactions. 2D 1H-1H double quantum single quantum (DQSQ) correlation SSNMR experiment is demonstrated which can confirm the formation of pharmaceutical eutectics for which there are no techniques other than differential scanning calorimetry (DSC).

}, issn = {1463-9076}, doi = {10.1039/d3cp05615e}, author = {Hareendran, Chaithanya and Shaligram, Parth S. and Gonnade, Rajesh and Ajithkumar, T. G.} } @article {49589, title = {Extraction of highly crystalline and thermally stable cellulose nanofiber from Heliconia psittacorum L.f. leaves}, journal = {International Journal of Biological Macromolecules}, volume = {308}, year = {2025}, month = {MAY}, pages = {142264}, type = {Article}, abstract = {

Extracting cellulose nanofibers (CNF) from agro-waste is one of the promising and practical ways to develop sustainable nanocomposites. In this study, cellulose nanofibers were extracted from the leaves of Heliconia psittacorum for the first time. The combination of oxalic acid hydrolysis (5 wt\%) and steam explosion was used for the isolation of CNF from the leaves of Heliconia psittacorum. The structural and chemical features of the prepared CNF were analyzed using various techniques, including Fourier Transform Infrared Spectroscopy (FTIR), Solid state 13C Nuclear Magnetic Resonance Spectroscopy (13C NMR), Scanning Electron Microscopy (SEM), Energy Dispersive X ray analysis (EDX), Transmission electron Microscopy (TEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA). TEM micrographs reported 15 to 40 nm diameter for the nanofibers synthesized. XRD analysis reported 91 \% crystallinity index for CNF, whereas that of the untreated sample was 76 \%. The maximum degradation of the CNF is reported at 355 degrees C, exceeds the untreated sample (316 degrees C). The tensile strength of the CNF derived paper was found to be 23 MPa. The recovered nanocellulose can be further utilized for various applications such as the automobile industry for developing lightweight parts, biosensors, super capacitors, absorption of greenhouse gases, wastewater treatment, and packaging applications.

}, keywords = {biomass valorization, Nanocellulose, Waste to resource}, issn = {0141-8130}, doi = {10.1016/j.ijbiomac.2025.142264}, author = {Paul, Sharon and Joseph, Anto and Hridhya, P. D. and Badawi, Michael and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and Asrofi, Mochamad and Dominic, C. D. Midhun} } @article {49457, title = {Green engineering of cellulose nanofibers and nanopapers from Wodyetia bifurcata fruits: a sustainable approach with emphasis on process optimization and tensile property assessment}, journal = {Biomass Conversion and Biorefinery}, volume = {15}, year = {2025}, month = {MAY}, pages = {9321-9335}, type = {Article}, abstract = {

Nanocellulose emerges as a highly promising material with versatile applications, offering solutions to environmental and sustainability challenges. This study delves into the extraction of cellulose nanofibers (CNFs) from\ Wodyetia bifurcata\ fruit pulp through mild oxalic acid hydrolysis assisted by steam explosion. To ensure environmental compatibility, chlorine-free pre-treatments were applied to eliminate non-cellulosic components. Chemical composition analysis verified the effective removal of non-cellulosic elements, validated by Fourier transform infrared spectroscopy (FTIR). Solid-state\ 13C nuclear magnetic resonance (13C NMR) spectroscopy confirmed the presence of type I cellulose α-polymorph in the CNF, while a crystallinity index of 60\% was determined by X-ray diffraction analysis (XRD). The transmission electron microscopy (TEM)\ images revealed a fibrous morphology with a fiber diameter ranging from 9 to 36\ nm. Dynamic light scattering (DLS) was employed to corroborate the observed fiber diameter. Mild acid hydrolysis elevated the maximum degradation temperature (Tmax) of CNF to 39\ {\textdegree}C compared to the pristine sample. Furthermore, this research explores the application of CNFs in nanopaper development using a casting method. The resulting nanopapers exhibited a tensile strength of ~ 17\ MPa and a transmittance of 25\%. These nanopapers present a viable pathway toward eco-friendly products in various industries, promising to revolutionize upcoming sustainable packaging technologies.

}, doi = {10.1007/s13399-024-05751-7}, author = {Sankar, Sameera and Neenu, K. V. and Parameswaranpillai, Jyotishkumar and Ajithkumar, T. G. and Shelke, Ankita Ramesh and Begum, P. M. Sabura and Bipinbal, P. K. and George, Tresa Sunitha and Badawi, Michael and Dominic, Midhun} } @article {49874, title = {Insights into the Chemical Durability and Structure of ZnO-Incorporated Sodium Borosilicate Glasses from Solid-State NMR}, journal = {Journal of Physical Chemistry B}, volume = {129}, year = {2025}, month = {JUL}, pages = {7349-7360}, type = {Article}, abstract = {

ZnO-incorporated NBS glasses have been studied for their application as a matrix for nuclear waste immobilization. However, structural factors affecting chemical durability have not been established. In this study, the structural changes in NBSZn glasses across various Na2O/(B2O3 + ZnO) ratios are explored using multinuclear MAS, MQMAS NMR, and EXAFS techniques. The Na MAS and MQMAS studies reveal remarkable changes in the Na environment after ZnO incorporation, which leads to an increase in chemical durability. Based on the results from NMR and EXAFS, we rationalized the structure of this glass in terms of the modified random network (MRN) model. The glass network comprises a highly polymerized region and alkali percolation channels bordered by nonbridging oxygens from the depolymerized regions. The constriction of these percolation channels increases the chemical durability of the glass. Our findings will help in the advancement of Zn-containing NBS glasses as a promising matrix for nuclear waste immobilization.

}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.4c07210}, author = {Illath, Kavya and Ananthanarayanan, Arvind and Banerjee, D. and Mishra, R. K. and Kumar, Ravi and Bhattacharya, D. and Kumar, Sanjay and Manohar, S. and Ajithkumar, T. G.} } @article {49962, title = {Ionic liquid driven Refined functionalization of graphene oxide: An insight via combined experiments and theory}, journal = {Carbon}, volume = {243}, year = {2025}, month = {AUG}, pages = {120571}, type = {Article}, abstract = {

Functionalizing graphene and its derivative, or doping them with heteroatoms can significantly enhance their optoelectronic, photonic and bio-photonic properties; but controlled and tuneable functionalization of GO is still in their infancy. Herein, a series of functionalized graphene oxide (FGO) are synthesized solvothermally by using task specific ionic liquids (ILs) of varying alkyl chain length; 1-alkyl-3-methylimidazolium tetra fluoroborate, [Cnmim]BF4 (n = 2, 4 etc.). ILs are not only used as a solvent but also as source of fluoride ion for functionalization of GO. A drastic decrease in the oxygen containing functional groups of GO upon fluorination is evidenced by FTIR, Raman, XPS, EDX analysis and electrochemical study. Solid state 19F NMR spectroscopy indicates that, fluorination happens exclusively in edge positions, not on basal planes. Band gap of FGOs decreases along with increasing the chain length of ILs. Further, intense blue emission and high photocatalytic efficiency, using crystal violet as model dye are observed for all the FGOs under visible light. The tailored functionalization by varying alkyl chain length of IL has been rationalized by DFT calculations. It has been realized that owing to the ease of dissociation for [Cnmim]BF4 complexes with n \>= 10; greater extent of fluorination/functionalization of GO has been observed. Elimination of a non-covalent interaction on increasing the alkyl chain length has been attributed for lower stability of higher chain length IL which in turn renders ease of dissociation. Easy yet controlled functionalization of GO using tuneable ILs can open a new direction in the environment friendly synthesis and applications.

}, keywords = {fluorination, Functionalization, graphene oxide, ionic liquids, Luminescence, Photocatalysis}, issn = {0008-6223}, doi = {10.1016/j.carbon.2025.120571}, author = {Kewat, Heera Lal and Dutta, Debangkana and Ajithkumar, T. G. and Chavda, Dhruvil and Sharma, Rahul Kumar and Tiwari, Mrityunjay K. and Sidiqi, Ubaid and Manna, Moutusi and Nigam, Sandeep and Ghosh, Pushpal} } @article {49515, title = {Probing the effect of fluorine on hydrogen bonding interactions in a pharmaceutical hydrate using Advanced Solid-State NMR}, journal = {Molecular Pharmaceutics}, volume = {22}, year = {2025}, month = {MAR }, pages = {1869-1880}, type = {Article}, abstract = {

Structural studies of pharmaceutical hydrates are essential to understanding stability-related issues, especially during the heating process of formulation. A thorough understanding of the hydration and dehydration behavior of active pharmaceutical ingredient (API) hydrate is also important since phase transitions can occur during the formulation process. This is because dehydration could result in a considerable rearrangement in the structure if water-API hydrogen bonding is present. We perform advanced solid-state NMR experiments on regorafenib monohydrate to investigate the role of fluorine in hydrogen bonding interaction, and the results are compared to its anhydrous form and its structural analogue, namely, sorafenib. Our results show that significant structural changes could not be observed on dehydration. Based on our study, it can be concluded that the introduction of fluorine restricts the intramolecular hydrogen bonding and the asymmetry in the structure of regorafenib monohydrate is absent, in comparison to sorafenib.

}, keywords = {DQSQ, Hydrogenbonding, pharmaceutical hydrate, regorafenib, Solid-state NMR}, issn = {1543-8384}, doi = {10.1021/acs.molpharmaceut.4c01055}, author = {Hareendran, Chaithanya and Ajithkumar, T. G.} } @article {49948, title = {Sustainable cellulose nanofiber extraction from Borassus flabellifer: a comprehensive study and analytical insights}, journal = {Biomass Conversion and Biorefinery}, volume = {15}, year = {2025}, month = {SEP}, pages = {25359-25373}, type = {Article}, abstract = {

Cellulose, a biodegradable and renewable material, is versatile and transforms various fields. This work uses a chemo-mechanical method to discuss the extraction and analysis of palmyra (Borassus flabellifer) fruit derived cellulose nanofibers (PFCNF). The mild acid treatment, steam explosion, and homogenization could increase the physico-chemical properties of Borassus flabellifer fiber. The chemical composition and FTIR analysis confirmed the successful elimination of the hemicellulose, lignin, and other extractives in the palmyra fruit pulp. The solid-state 13C NMR proved the cellulose type I structure of the extracted PFCNF. The crystallinity index of PFCNF was found to be 57\%. The yield of the cellulose was calculated to be 44\%. PFCNF exhibited fibrous morphology with a nanodimension of 10-80 nm, validated using scanning electron microscopy and transmission electron microscopy. With progressive treatments, the thermal stability was increased, and the Tmax of PFCNF was 32 degrees C higher compared to the raw fibers. These superior properties further support their potential in eco-friendly packaging, advanced composites, biomedical materials, film production, electronics, coating materials, and paper production.

}, keywords = {Borassus flabellifer, Biomass, Cellulose nanofiber, Eco-friendly extraction, Sustainable materials, Waste valorization}, issn = {2190-6815}, doi = {10.1007/s13399-025-06859-0}, author = {Surya, S. and Soman, Arathy and Krishnan, Akhil and Suresh, M. Parvana and Neenu, K. V. and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and Begum, P. M. Sabura and Dominic, C. D. Midhun} } @article {49961, title = {Sustainable isolation of cellulose nanofibers with superior crystallinity and thermal stability from Terminalia catappa L. fruit peel waste}, journal = {Biomass Conversion and Biorefinery}, volume = {15}, year = {2025}, month = {JUL}, pages = {21557-21572}, type = {Article}, abstract = {

Turning agricultural waste into value-added products is a key focus of sustainable development. Herein, cellulose nanofibers (CNF) were extracted from the pericarp of Terminalia catappa L. for the first time. The CNF was extracted by chlorine-free pretreatment methods followed by oxalic acid hydrolysis (5 wt\%) assisted with steam explosion. The prepared CNF were characterized by Fourier transform infrared spectroscopy (FTIR), solid-state 13C nuclear magnetic resonance spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA and DTG). FTIR analysis confirmed the successful removal of lignin and hemicellulose during chemical treatment which was again validated by solid-state 13C NMR analysis. TEM image revealed that the diameter of the extracted nanofibers ranges from 14 to 18 nm. From XRD analysis, the crystallinity index of the CNF was 82\%, while that of the raw sample was 62 \%. The temperature at which the maximum degradation (Tmax) of CNF occurred was found to be 372 degrees C which is superior to that of the raw sample (334 degrees C). The extracted cellulose nanofibers were used to prepare cellulose paper, demonstrating a tensile strength of 1.1 MPa, indicating its potential suitability for biodegradable packaging applications.

}, keywords = {cellulose, Cellulose nanofiber, green synthesis, Waste to wealth}, issn = {2190-6815}, doi = {10.1007/s13399-025-06726-y}, author = {Harsha, R. and Mol, A. P. Princy and Paul, Sharon and Badawi, Michael and Ajithkumar, T. G. and Rao, H. Jeevan and Parameswaranpillai, Jyotishkumar and Nair, Ajalesh B. and Begum, P. M. Sabura and Dominic, C. D. Midhun} } @article {49460, title = {Valorization of avocado peel waste: extraction and characterization of cellulose nanofibers for multifunctional applications}, journal = { Biomass Conversion and Biorefinery}, volume = {15}, year = {2025}, month = {APR}, pages = {12789-12800}, type = {Article}, abstract = {

This study explored the utility of underutilized avocado peels for extracting cellulose nanofibers (CNFs). Mild oxalic acid hydrolysis assisted by steam explosion was employed after alkali hydrolysis and chlorine-free bleaching to prepare cellulose nanofibers. The structural, atomic, and elemental features of the extracted fibers were studied using Fourier transform infrared spectroscopy (FTIR),\ 13C solid-state nuclear magnetic resonance (13C NMR) spectroscopy, and energy dispersive X-ray (EDAX) analysis, respectively. The crystallinity index of the nanofibers was 87\%, which was 53\% greater than that of the crude sample. The elution of hemicellulose and lignin was evident from the scanning electron microscopy (SEM) images, and the nanofibers had a fiber diameter of 30{\textendash}82\ nm according to the transmission electron microscopy (TEM) analysis. The applied chemical treatment also elevated the thermal stability of the fibers. The extracted fibers can be applied in numerous fields, including electronics, packaging, automobiles, biomedicine, and cosmetics.

}, doi = {https://doi.org/10.1007/s13399-024-06065-4}, author = {Varsha, P. V. and Neenu, K. V. and Begum, P. M. Sabura and Hounfodji, Jean Wilfried and Sankar, Sameera and Muraleedharan, Sneha and Kamath, Anjali N. and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and Midhun, Dominic C. D.} } @article {50044, title = {Effect of sulfonation density on acid strength in ion exchange resins: Insights from solid-state NMR and density functional theory}, journal = {Molecular Catalysis}, volume = {593}, year = {2026}, month = {MAR }, pages = {115794}, type = {Article}, abstract = {

Ion-exchange (IE) resins are widely used as solid acid catalysts; however, their surface acidity remains poorly characterized because their limited thermal stability precludes conventional NH3-based acidity measurements. Moreover, acid-site accessibility in IE resins is strongly governed by solvent- or reactant-induced swelling. Here, we investigate the surface acidity of commercial Amberlyst and Indion IE resins using \& sup3;\& sup1;P MAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance), employing TMPO as a molecular probe dispersed on the resin with moderately swelling dichloromethane, thereby capturing the swollen-state acidity relevant for predicting catalytic activity. The deconvolution of the P-31 MAS NMR spectra reveals three distinct acid-strength zones arising from inhomogeneous sulfonation of the polymer matrix. The overall acidity, quantified by the area-weighted average P-31 chemical shift (delta), increases monotonically with sulfonation density. Notably, only resins containing acid sites stronger than similar to 80 ppm exhibited measurable catalytic activity in alpha-pinene isomerization, establishing a direct correlation between acidity and activity. Density functional theory (DFT) calculations on representative resin models, supported by electron-density analyses, attribute the enhancement of acid strength at higher sulfonation densities to cooperative hydrogen-bonding networks among neighboring sulfonic acid groups. Together, these findings establish P-31 MAS NMR-derived surface acidity as a catalytically relevant descriptor for the rational selection of IE resins in liquid phase acid-catalyzed chemistries.

}, keywords = {Acid strength, Density functional theory, heterogeneous catalysis, Ion-exchange resins, Solid acids, Solid-state NMR}, issn = {2468-8231}, doi = {10.1016/j.mcat.2026.115794}, author = {Tumulu, Goutam Narayan and Datar, Sarvesh and Shelke, Ankita and Swain, Gitanjali and Ajithkumar, T. G. and Thirumalaiswamy, Raja and Mohan, Ojus and Mahajani, Sanjay M.} } @article {50075, title = {Fly-ash-based geopolymers: leachability and solid-state NMR investigations}, journal = {Bulletin of Materials Science}, volume = {49}, year = {2026}, month = {MAR}, pages = {54}, type = {Article}, abstract = {

This study aims to explore how leaching impacts the microstructure of a selected fly ash-derived geopolymer and evaluate its potential for near-surface disposal of radioactive waste. The uniqueness of this geopolymer formulation is its ability to form an aluminosilicate network that remains resistant to structural changes upon contact with water. The leach index of base elements such as Ca, Al, Na and Si was between 11 and 13, suggesting that the formulation is superior to Portland cement or conventional hydraulic cement. Solid-state NMR reveals that the water-interacted specimen has no contamination of the zeolite phase and all the Na is incorporated into the aluminosilicate geopolymer gel network, which also confirms that the glassy network of the geopolymer is responsible for imparting low leachability of base elements from its structure, and there is no labile sodium available for exchange as in zeolites.

}, keywords = {aluminosilicate network, Fly ash, Geopolymers, leaching, Solid-state NMR}, issn = {0250-4707}, doi = {10.1007/s12034-025-03487-2}, author = {Nadol, Athulya and Ajithkumar, T. G. and Singla, Rashmi and Alex, T. C. and Kumar, Sanjay and Bhatt, Himal and Deo, M. N. and Sen, Debasis and Ambashta, R. D. and Bajpai, R. K. and Shivakumar, Y. C. and Manohar, S.} } @article {50137, title = {Insights into the structure and electrochemical properties of Ti3C2T x MXene from solid-state NMR}, journal = {Journal of Physical Chemistry C}, volume = {130}, year = {2026}, month = {MAY}, pages = {7069-7078}, type = {Article}, abstract = {

Ever since their discovery in 2011, MXenes have gained popularity in energy storage devices. Their far-reaching properties arise mainly due to surface terminations and interlayer species like hydrated cations and water. The nature of these species remains a subject of study due to the complex surface functionalization during synthesis. X-ray diffraction studies have shown that certain intercalants such as hydrated cations increase the interlayer spacing leading to enhanced electrochemical performance. However, the structural and chemical modification of these intercalants during the charge-discharge cycles of asymmetric supercapacitors are yet to be investigated. Analysis of the complex chemistry of Ti3C2Tx requires a specialized tool that can provide insights into its nuanced structural changes and link them to its behavior. In this study, we demonstrate the versatility of solid-state NMR (SSNMR), for the characterization of surface terminations and intercalants in the Ti3C2Tx MXene prepared using sodium salts, and correlate its structure to its performance by ex situ SSNMR analysis. Our experiments demonstrate the progressive oxidation of surface Ti-OH and also the significance of the intercalated hydrated cation shells during electrochemical cycling. In addition to this, we have also employed Na-23 MAS SSNMR to demonstrate the conversion of sodium hexahydrate to sodium peroxides after 10 charge-discharge cycles.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5c05653}, author = {Balasubramanian, Rajalakshmi and Puthiyaveetil, Priyanka Pandinhare and Kurungot, Sreekumar and Ajithkumar, T. G.} } @article {49835, title = {Self-healing hydrogel electrolyte enabled by dynamic polar covalent and noncovalent interactions for high-performance rechargeable zinc-metal batteries: a leap toward sustainable energy storage}, journal = {Advanced Energy Materials}, volume = {16}, year = {2026}, month = {JAN}, type = {Article}, abstract = {

Hydrogel polymer electrolytes with superior multifunctional properties are promising alternatives to aqueous electrolytes for resolving interfacial issues in rechargeable zinc-metal batteries. In this study, an intrinsic self-healing hydrogel polymer electrolyte (PHBC-4) is synthesized, engineered through an integrated approach involving the polar covalent (B \& horbar;O bond), hydrogen-bond (polyvinyl alcohol-hydroxypropyl methylcellulose interface), and coordination-type (Zn \& horbar;O) interactions to enable self-healing functionality. The PHBC-4 has demonstrated high ionic conductivity (4.6 x 10-2 S cm-1), good oxidative stability (2.3 V vs Zn|Zn2+), a high cation transference number (0.89), superior tensile strength (0.32 MPa), and an impressive healing efficiency of 93\% achieved just within 5 min, confirming its robust self-healing capability. In Zn||Zn symmetric cells, it effectively suppresses dendrite growth, ensuring stable cycling for over 1032 h with an areal capacity of 1.0 mAh cm-2 at a current density of 1.0 mA cm-2. When paired with a Zn-doped MnO cathode in the rechargeable homemade pouch cell, the system delivers a high specific capacity of 160 mAh g-1 at 0.10 A g-1 and cycling stability up to 493 charge-discharge cycles at 2.0 A g-1. The self-healing ability of PHBC-4 HGPE is confirmed in a homemade pouch cell via OCV and charge-discharge tests, demonstrating stable performance. The DFT studies confirm molecular-level interactions within the hydrogel heterostructure.

}, keywords = {dendrite inhibition, flexible rechargeable zinc metal battery, high cation transference number, self-healing hydrogel polymer electrolyte}, issn = {1614-6832}, doi = {10.1002/aenm.202502883}, author = {Puthiyaveetil, Priyanka Pandinhare and Kurian, Rachna Maria and Samudre, Nikhil S. and Balasubramanian, Rajalakshmi and Torris, Arun and Pockil, Fayis Kanheeram and Bhat, Suresh and Ajithkumar, T. G. and Krishnamurty, Sailaja and Kurungot, Sreekumar} } @article {50171, title = {Upcycling used lottery tickets: extraction, characterization, and life cycle assessment of cellulose nanofibers using a cradle-to-gate approach}, journal = {Materials Chemistry and Physics}, volume = {357}, year = {2026}, month = {JUN}, pages = {132353}, type = {Article}, abstract = {

This work examines a sustainable approach for the isolation, characterization and Life Cycle Impact Assessment of cellulose nanofibers derived from post-consumer lottery tickets. The lottery tickets were subjected to bleaching using 15\% H2O2 and 10\% NaOH in a 5:1 ratio at 80 degrees C, followed by acid hydrolysis using 5\% oxalic acid assisted with steam explosion. The isolated cellulose nanofibers were 16 to 36 nm diameter range with a crystallinity index of 84.5\%. The zeta potential value of-25.19 mV revealed moderate colloidal stability for nanocellulose suspension. The thermal stability of nanocellulose fibers was reported around 300 degrees C in N2 atmosphere. The films fabricated from the nanocellulose fibers reported a tensile strength of 4.6 +/- 0.90 MPa. The cradle-to-gate Life Cycle Impact Assessment revealed the impact of electricity consumption and bleaching process on the isolation of nanocellulose from waste lottery paper. These findings underline the potential of waste-derived CNFs for sus-tainable applications such as biodegradable packaging while promoting circular economy principles and green nanotechnology through waste valorisation, eco-friendly chemistry, and life cycle sustainability.

}, keywords = {Cellulose nanofibers (CNFs), Life cycle impact assessment, Lottery tickets, Waste to wealth}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2026.132353}, author = {Madhu, Athulya K. and Rosa, Derval Santos and de Oliveira, Sueli Aparecida and Ajithkumar, T. G. and Parameswaranpillai, Jyotishkumar and Badawi, Michael and Dominic, C. D. Midhun} }