@article { ISI:000341543200034, title = {Soft colloidal scaffolds capable of elastic recovery after large compressive strains}, journal = {Chemistry of Materials}, volume = {26}, number = {17}, year = {2014}, month = {SEP}, pages = {5161-5168}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Assemblies of inorganic or glassy particles are typically brittle and cannot sustain even moderate deformations. This restricts the use of such materials to applications where they do not experience significant loading or deformation. Here, we demonstrate a general strategy to create centimeter-size macroporous monoliths, composed primarily (\>90 wt \%) of colloidal particles, that recover elastically after compression to about one-tenth their original size. We employ ice templating of an aqueous dispersion of particles, polymer, and cross-linker such that cross-linking happens in the frozen state. This method yields elastic composite scaffolds for starting materials ranging from nanoparticles to micron-sized dispersions of inorganics or glassy lattices. The mechanical response of the monoliths is also qualitatively independent of polymer type, molecular weight, and even cross-linking chemistry. Our results suggest that the monolith mechanical properties arise from the formation of a unique hybrid microstructure, generated by cross-linking the polymer during ice templating. Particles that comprise the scaffold walls are connected by a cross-linked polymeric mesh. This microstructure results in soft monoliths, with moduli similar to O (10(4) Pa), despite the very high particle content in their walls. A remarkable consequence of this microstructure is that the monolith mechanical response is entropic in origin: the modulus of these scaffolds increases with temperature over a range of 140 K. We show that interparticle connections formed by cross-linking during ice templating determine the monolith modulus and also allow relative motion between connected particles, resulting in entropic elasticity.

}, issn = {0897-4756}, doi = {10.1021/cm502643a}, author = {Rajamanickam, Raja and Kumar, Sushma and Kumar, Deepak and Ghosh, Shankar and Kim, Jong Chul and Tae, Giyoong and Sen Gupta, Sayam and Kumaraswamy, Guruswamy} } @article {43446, title = {N-2 activation on Al metal clusters: catalyzing role of BN-doped graphene support}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, year = {2016}, month = {OCT}, pages = {27721-27727}, abstract = {The successful sustenance of life demands an ambient abiotic process for N-2 activation and dissociation. The Bosch-Haber process remains the only abiotic and synthetic means for N-2 activation and its fixation. Metal nanoclusters have been recently reported for activating molecular nitrogen. Interestingly, the metal clusters explored so far for N-2 activation are free clusters and, hence, are practically not applicable by experimental chemists. Using density functional theory (DFT) based methodology, we propose a potential catalytic system for di-nitrogen activation, viz. supported Al clusters. Al clusters supported on BN doped graphene sheets are seen to activate N-2 molecule with a red shift in the N-N stretching frequency up to 874 cm(-1) with activation barriers as low as 1.14 eV.}, doi = {10.1039/c6cp03342c}, author = {Kumar, Deepak and Pal, Sourav and Krishnamurty, Sailaja} } @article {45638, title = {Strategic Preparation of Efficient and Durable NiCo Alloy Supported N-Doped Porous Graphene as an Oxygen Evolution Electrocatalyst: A Theoretical and Experimental Investigation}, journal = {Advanced Materials Interfaces}, volume = {3}, year = {2016}, month = {OCT }, pages = {1600532}, type = {Article}, abstract = {

Development of an efficient and durable water splitting electrocatalyst holds a great commitment for the future energy devices. The real application of oxygen evolution reaction (OER) catalysts mainly suffers from sluggish kinetics and high overpotential except for the Ir and Ru-based systems. However, the high cost and vulnerability of the Ir and Ru metals are the main hostiles to use them for marketization. Herein, a high-performance OER electrocatalyst consisting of NiCo alloy nanoparticles supported on high surface area N-doped porous graphene (NiCo/pNGr(75: 25)) is reported. The importance of the doped-N for achieving the uniform dispersion-cum-effective interaction of the size controlled NiCo alloy nanoparticles has been explicitly investigated by transmission electron microscopy, X-ray diffraction, X-ray photo electron spectroscopy, Raman, density functional theory (DFT) calculations, etc. The electrochemical analysis of NiCo/pNGr(75: 25) shows an overpotential of approximate to 260 mV at 10 mA cm(-2) with a smaller Tafel slope of approximate to 87 mV dec(-1) and long catalytic durability. DFT calculations are done to check the interaction between the NiCo alloy nanoparticles and the defective sites of pNGr and also with the doped-N, which could be attained for maintaining long catalytic durability. Furthermore, NiCo/pNGr(75: 25) is used as an OER catalyst to fabricate an electrolyzer, which works at very low potential of 1.5 V in 1 M KOH.

}, issn = {2196-7350}, doi = {10.1002/admi.201600532}, author = {Singh, Santosh K. and Kumar, Deepak and Dhavale, Vishal M. and Pal, Sourav and Kurungot, Sreekumar} } @article {44123, title = {Dissociative adsorption of molecular hydrogen on BN-doped graphene-supported aluminum clusters}, journal = {Journal of Physical Chemistry C}, volume = {121}, year = {2017}, month = {NOV}, pages = {26493-26498}, type = {Article}, abstract = {The present work demonstrates dissociative adsorption of molecular hydrogen on supported and unsupported aluminum Wclusters (Al-n, n = 4-8, 13) using density functional theory based calculations. The studies reveal that the presence of a BN-doped graphene surface support reduces the dissociative adsorption barrier of the bond in molecular hydrogen on even atom clusters. In particular, supported Al-6 demonstrates a barrier-less dissociative adsorption toward the H-2 molecule. These results demonstrate the excellent potential of supported Al nanoparticles for hydrogen storage and also the potential of doped graphene systems are catalyzing supports.}, doi = {10.1021/acs.jpcc.7b07789}, author = {Kumar, Deepak and Krishnamurty, Sailaja and Pal, Sourav} } @article {45371, title = {Dissociative chemisorption of hydrogen molecules on defective graphene-supported aluminium clusters: a computational study}, journal = {Physical Chemistry Chemical Physics }, volume = {20}, year = {2018}, month = {NOV}, pages = {26506-26512}, type = {Article}, abstract = {

Using periodic density functional theory-based calculations, in the present study, we address the chemical bonding between aluminium clusters (Al-n, n = 4-8 and 13) and monovacant defective graphene. The adsorption strength of the above-mentioned aluminium clusters is fivefold (approximate to 3 to 5 eV) higher on defective graphene as compared to the earlier reported values on non-defective graphene and BN-doped graphene. The Bader charge analysis and different charge densities reveal that this adsorption is driven by significant charge transfer from the Al clusters to defective graphene. Thus, chemisorbed Al clusters demonstrate high activity towards dissociative adsorption of molecular hydrogen.

}, issn = { 1463-9076}, doi = {10.1039/c8cp05711g}, author = {Kumar, Deepak and Govindaraja, Thillai and Krishnamurty, Sailaja and Kaliaperumal, Selvaraj and Pal, Sourav} } @article {46344, title = {Crystal engineering for intramolecular pi-pi stacking: effect of sequential substitution of f on molecular geometry in conformationally flexible sulfonamides}, journal = {Crystal Growth \& Design}, volume = {19}, year = {2019}, month = {OCT}, pages = {5665-5678}, type = {Article}, abstract = {

A small library of ten sulfonamide derivatives comprising two aromatic rings was synthesized to investigate the effect of chronological positioning of the F-atom on the intramolecular pi-stacking assembly. The sequential positioning of F atoms was carried out on one of the aromatic rings that is linked to the sulfonamide moiety directly while the other aromatic ring (phenyl or pyridine) is linked by an ethyl spacer with the sulfonamide moiety. The ethyl spacer is provided to achieve the required flexibility so that both aromatic rings can bend to acquire syn conformation facilitated pi-stacking between electron-deficient and electron-rich aromatic rings. The idea was to study the interplay between hydrogen bonding and pi-stacking synthons in the conformationally flexible sulfonamide derivatives. The solid-state conformation of all the derivatives was investigated using the single-crystal X-ray diffraction technique. Crystal structure analysis revealed that the syn conformation was achieved only in trifluoro and pentafluoro sulfonamide derivatives with benzene substitution while in all other derivatives the molecules take either midway or anti conformations. None of the sulfonamide molecules with a pyridine moiety showed syn conformation. It could be because of the involvement of the pyridine N-atom in the hydrogen bonding dimeric synthon. The molecular conformation study in solution state using 2D NOESY and HOESY NMR experiments also substantiated syn conformation in a pentafluoro sulfonamide molecule with benzene substitution. The conformational analysis carried out employing density functional theory (DFT) calculations confirmed higher stability for the syn conformation over midway and anti orientations.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.9b00667}, author = {Shaikh, Samir R. and Gawade, Rupesh L. and Kumar, Deepak and Kotmale, Amol and Gonnade, Rajesh G. and Stuerzer, Tobias} } @article {47108, title = {Synthesis and cell imaging applications of fluorescent mono/di/tri-heterocyclyl-2,6-dicyanoanilines (vol 27, pg 979, 2017)}, journal = {Bioorganic \& Medicinal Chemistry Letters}, volume = {32}, year = {2021}, month = {JAN }, pages = {127737}, type = {Correction}, issn = {0960-894X}, doi = {10.1016/j.bmcl.2020.127737}, author = {Pisal, Mahesh M. and Annadate, Ritesh A. and Athalye, Meghana C. and Kumar, Deepak and Chavan, Subhash P. and Sarkar, Dhiman and Borate, Hanumant B.} } @article {48809, title = {Theory-directed designing of an intrinsic-activity-modulated metal-doped copper oxide electrode for nitrate to ammonia synthesis}, journal = {ACS Applied Energy Materials}, volume = {6}, year = {2023}, month = {MAY}, pages = {6111-6119}, type = {Article}, abstract = {

Synthesis of ammonia via electrochemical reduction ofnitrate isone of the most sustainable routes both for environmental protectionas well as energy saving initiatives. However, this process is limitedto the development of high-performance free-standing catalytic electrodeswith improved selectivity and Faradaic efficiency. Herein, we reporttheory-guided designing and fabrication of free-standing non-noblemetal (Mn, Fe, and Co)-doped copper oxide (CuO) electrodes by usinga simple and scalable electrode preparation method. The density functionaltheory (DFT)-based calculations show that the doped-Co sites in theCu surface facilitate the generation and supply of H+ tothe adsorbed NO3 (-) during the reductionprocess; as a result, the Co-CuO catalyst displays higher selectivitytoward nitrate reduction. The Co-doped Cu electrode (Co-CuO)delivers a higher NH3 yield (5492 mu g cm(-2)) at a reduction potential of -0.91 V vs RHE while maintaininga Faradaic efficiency of \>95\%. The alloying of Co to the coppermetalnot only facilitates the proton donation to the adsorbed reactant(NO3 (-)) but also tunes the Cu d-center,resulting in the active site modulation responsible for the activationof catalysts.

}, keywords = {Active sites, ammonia synthesis, electrocatalysis, Faradaic efficiency, High selectivity, metal-doped electrode}, issn = {2574-0962}, doi = {10.1021/acsaem.3c00617}, author = {Tyagi, Nitin Kumar and Mahapatra, Bikash K. and Ghimire, Suvash and Manna, Narugopal and Kumar, Deepak and Kumar, Vijay and Mukhopadhyay, Kausik and Singh, Santosh K.} }