@article { ISI:000250234900007, title = {Fabrication of an effusive molecular beam instrument for surface reaction kinetics - CO oxidation and NO reduction on Pd(111) surfaces}, journal = {Catalysis Letters}, volume = {119}, number = {1-2}, year = {2007}, month = {NOV}, pages = {50-58}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING STREET, NEW YORK, NY 10013 USA}, abstract = {

A simple molecular beam instrument (MBI) was fabricated for measuring the fundamental parameters in catalysis such as, sticking coefficient, transient and steady state kinetics and reaction mechanism of gas/vapor phase reactions on metal surfaces. Important aspects of MBI fabrication are given in detail. Nitric oxide (NO) decomposition and NO reduction with carbon monoxide (CO) on Pd(111) surfaces were studied. Interesting results were observed for the above reactions and they support the efficiency of the MBI to derive the fundamental parameters of adsorption and catalysis. Sustenance of CO oxidation at 400 K is dependent mostly on the absence of CO-poisoning; apparently, CO + O recombination is the rate determining step \<= 400 K. NO adsorption measurements on Pd(111) surface clearly indicating a typical precursor kinetics. Displacement of the chemisorbed CO by NO on Pd(111) surfaces was observed directly with NO + CO beams in the transient kinetics. It is also relatively easy to identify the rate-determining step directly from the MBI data and the same was demonstrated for the above reactions.

}, keywords = {carbon monoxide, catalysis, kinetics, molecular beam, nitric oxide, Pd(111)}, issn = {1011-372X}, doi = {10.1007/s10562-007-9184-8}, author = {Thirunavukkarasu, Kandasamy and Gopinath, Chinnakonda S.} } @article { ISI:000284238000010, title = {Fabrication of homogeneous nanoparticle/nanoneedle BaTiO3 and Ba0.8Sr0.2TiO3 smooth thin films by simple dip coating}, journal = {International Journal of Nanotechnology}, volume = {7}, number = {9-12, SI}, year = {2010}, month = {DEC}, pages = {919-931}, publisher = {INDERSCIENCE ENTERPRISES LTD}, address = {WORLD TRADE CENTER BLDG, 29 ROUTE DE PRE-BOIS, CASE POSTALE 896, CH-1215 GENEVA, SWITZERLAND}, abstract = {

Ferroelectric BaTiO3 (BTO) and Ba0.8Sr0.2TiO3 (BSTO) thin film materials have been successfully prepared by sol-gel processing and simple dip coating on glass and silicon supports. Above thin films were characterised by x-ray diffraction (XRD), Raman spectroscopy, photoelectron spectroscopy, thermal analysis, atomic force microscopy (AFM) and spectroscopic ellipsometry. Phase identification of BaTiO3 and Ba0.8Sr0.2TiO3 was performed by XRD. XRD and Raman spectroscopy investigations demonstrate that thc Ba0.8Sr0.2TiO3 film exhibits tetragonal structure. AFM analysis demonstrates the elongated nanospherical particles on glass substrate and nanowires on silicon substrate, which represent a strong influence of the crystallinity of underlying substrate on the grain morphology in this technique. The thin films on both the substrates are uniformly coated without any pinhole to significant area (similar to 2.5 cm(2)), and this method might be extended to large area uniform coating. Spectroscopic ellipsometric measurements reveal the exact thickness, refractive index and extinction coefficient of the thin films.

}, keywords = {barium strontium titanate, barium titanate, dip coating, fabrication, ferroelectric material, large area coating, nanotechnology, thin film}, issn = {1475-7435}, author = {Saini, Mamta and Vivekanand, K. and Poddar, Pankaj and Murty, K. V. G. K. and Thushara, K. S. and Gopinath, Chinnakonda S.} } @article { ISI:000284018100044, title = {Facile synthesis of N- and S-incorporated nanocrystalline TiO2 and direct solar-light-driven photocatalytic activity}, journal = {Journal of Physical Chemistry C}, volume = {114}, number = {45}, year = {2010}, month = {NOV}, pages = {19473-19482}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Sulfur- and nitrogen-incorporated mesoporous TiO2 (SNT) nanocomposites have been synthesized by a template-free homogeneous coprecipitation technique. The above nanocomposites have been thoroughly characterized by physicochemical and spectroscopy methods to explore the structural, electronic, and optical properties. The photocatalytic activities of the catalysts were evaluated for the degradation of methyl orange and phenol under direct solar light. SNT shows about a 2-fold higher photocatalytic activity than singly N-doped or S-doped mesoporous TiO2 and 3-fold higher than Degussa P25. The higher activity might be attributed to the synergetic interaction of sulfate and nitrogen with the TiO2 lattice. N-Ti-O and O-Ti-N-O environments are responsible for a red shift, and the sulfate group on TiO2 acts as a cocatalyst, for increasing surface acidity as well as for sustaining the redox cycles for high stability.

}, issn = {1932-7447}, doi = {10.1021/jp1083345}, author = {Naik, Brundabana and Parida, K. M. and Gopinath, Chinnakonda S.} } @article { ISI:000319027400029, title = {Functional and disordered meso-macroporous gamma-Al2-xMxO3 +/- y (M = Cu and/or Ce)}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {13}, number = {4, SI}, year = {2013}, month = {APR}, pages = {2682-2688}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {Disordered meso-macro porous Cu-Ce-Al2O3 nanocomposite (gamma-Al2-xMxO3 +/- y, M = Cu and or Ce) with different compositions has been synthesized. In situ templated sol-gel method has been adopted with simple EDTA ethylenediamine tetra aceticacid and ethylenediamine molecules to prepare gamma-Al2-xMxO3 +/- y, (M = Cu and or Ce). Above meso-macro porous materials were characterized by structural, spectroscopy, microscopy and textural techniques. Detailed characterization indicates that Cu2+ ions are introduced into the ceria and alumina lattice positions. Nano composite nature of the gamma-Al2-xMxO3 +/- y has been confirmed by detailed microscopy investigations. Catalytic activity of the above nanocomposite materials have been screened for environmentally important CO oxidation reaction. 30\% Ce-60\% Al and 10\% Cu containing material shows the best activity among other meso-nnacroporous material with (50\%) 100\% CO oxidation at (107 degrees C) 145 degrees C.}, keywords = {Alumina, CO oxidation, heterogeneous catalysis, Meso-Macroporous Material, Nanocomposite, Sol-gel synthesis}, issn = {1533-4880}, doi = {10.1166/jnn.2013.7384}, author = {Gnanakumar, Edwin S. and John, Jino C. and Raja, Thirumalaiswamy and Gopinath, Chinnakonda S.} } @article { ISI:000341065800011, title = {Facile method for the synthesis of Co-core Au-shell nanohybrid}, journal = {New Journal Of Chemistry}, volume = {38}, number = {9}, year = {2014}, month = {SEP}, pages = {4107-4114}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Heterostructured Co-Au core-shell nanoparticles have been synthesized by reducing AuCl4- ions on cobalt nanoparticles after a minor but effective modification of cobalt surface by an amine. The core shell morphology is emphatically confirmed by thorough investigation through UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopic analysis (TEM). The chemical composition and topography were determined using STEM-HAADF analysis and EFTEM imaging. Fourier transform infrared (FTIR) spectroscopy confirms the surface modification of Co nanoparticles and the interactions involved between the ligands and the core and shell metals at various steps of the synthetic process. The magnetic properties confirm the material to be superparamagnetic in nature.

}, issn = {1144-0546}, doi = {10.1039/c4nj00733f}, author = {Sardar, Debasmita and Neogi, S. K. and Bandyopadhyay, Sanjoy and Satpati, Biswarup and Jain, Ruchi and Gopinath, Chinnakonda S. and Bala, Tanushree} } @article { ISI:000332144600065, title = {Facile single-step synthesis of nitrogen-doped reduced graphene oxide-Mn3O4 hybrid functional material for the electrocatalytic reduction of oxygen}, journal = {ACS Applied Materials \& Interfaces}, volume = {6}, number = {4}, year = {2014}, month = {FEB}, pages = {2692-2699}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Development of efficient electrocatalyst based on non-precious metal that favors the four-electron pathway for the reduction of oxygen in alkaline fuel cell is a challenging task. Herein, we demonstrate a new facile route for the synthesis of hybrid functional electrocatalyst based on nitrogen-doped reduced graphene oxide (N-rGO) and Mn3O4 with pronounced electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline solution. The synthesis involves one-step in situ reduction of both graphene oxide (GO) and Mn(VII), growth of Mn3O4 nanocrystals and nitrogen doping onto the carbon framework using a single reducing agent, hydrazine. The X-ray photoelectron (XPS), Raman and FTIR spectral, and X-ray diffraction measurements confirm the reduction of GO and growth of nanosized Mn3O4. The XPS profile reveals that N-rGO has pyridinic (40\%), pyrrolic (53\%), and pyridine N oxide (7\%) types of nitrogen. The Mn3O4 nanoparticles are single crystalline and randomly distributed over the wrinkled N-rGO sheets. The hybrid material has excellent ORR activity and it favors the 4-electron pathway for the reduction of oxygen. The electrocatalytic performance of the hybrid catalyst is superior to the N-rGO, free Mn3O4 and their physical mixture. The hybrid material shows an onset potential of -0.075 V, which is 60-225 mV less negative than that of the other catalyst tested. It has excellent methanol tolerance and high durability. The catalytic current density achieved with the hybrid material at 0.1 mg cm(-2) is almost equivalent to that of the commercial Pt/C (10\%). The synergistic effect of N-rGO and Mn3O4 enhances the overall performance of the hybrid catalyst. The nitrogen in N-rGO is considered to be at the interface to bridge the rGO framework and Mn3O4 nanoparticles and facilitates the electron transfer.

}, keywords = {electrocatalysis, hybrid material, Mn3O4, nitrogen-doped graphene, oxygen reduction, synergistic effect}, issn = {1944-8244}, doi = {10.1021/am405213z}, author = {Bag, Sourav and Roy, Kanak and Gopinath, Chinnakonda S. and Raj, C. Retna} } @article {44138, title = {Facile synthesis of Al2O3-Pt nanocomposite and its catalytic activity}, journal = {Materials Research Express}, volume = {4}, year = {2017}, month = {NOV}, pages = {Article Number: 115002}, type = {Article}, abstract = {Pt nanoparticles were synthesized on gamma-alumina support in presence of oleic acid which was found to prevent clustering of Pt nanoparticles on the support. Various percentage of Pt loading on the alumina changed the catalytic activity for preferential oxidation of CO at relatively low temperature in H-2 rich stream. Pt nanoparticles when synthesized in absence of oleic acid, were all clustered and did not have any catalytic activity. The presence of oleic acid promoted stability preventing agglomeration of Pt nanoparticles. The catalyst thus prepared was characterized thoroughly and their catalytic activity was studied in details.}, doi = {10.1088/2053-1591/aa9441}, author = {Das, Subhasis and Bordoloi, Ankur and Ghosalya, Manoj Kumar and Gopinath, Chinnakonda S. and Bala, Tanushree} } @article {43705, title = {Facile synthesis of ZnO-Ag nanocomposite and its photocatalytic activity}, journal = {Materials Research Express}, volume = {4}, year = {2017}, month = {MAY}, pages = {Article Number: 055011}, type = {Article}, abstract = {

The evolution of photoactive hybrid materials (e.g. noble metal-semiconductor) has resulted in heterogeneous photocatalysis. We report a facile route for the synthesis of ZnO-Ag nanocomposites with varying percentage of loading of the noble metal, expecting a great boost in the photocatalytic behavior of ZnO. The as prepared material was thoroughly characterized by UV-Vis, FTIR, TEM, FESEM, XRD, XPS analyses. The photocatalytic activities of the nanocomposites have been assessed from the ability to degrade methylene blue dye in aqueous solution. The results suggest that incorporation of Ag nanoparticles on the surface of ZnO particles can enhance catalytic activity in comparison to pure ZnO particles under visible light by minimizing the recombination of photogenerated electron-hole pairs.

}, doi = {10.1088/2053-1591/aa6df1}, author = {Sardar, Debasmita and Maity, Jayeta and Ghosalya, Manoj Kumar and Gopinath, Chinnakonda S. and Bala, Tanushree} } @article {48077, title = {Facile, sustainable and unassisted plain water oxidation on Au/Ce0.9Ti0.1O2 nanorods in direct sunlight}, journal = {Journal of Chemical Sciences}, volume = {134}, year = {2022}, month = {JUN}, pages = {61}, type = {Article}, abstract = {

Impressive rate of solar water oxidation to molecular oxygen (O-2) has been demonstrated on nanorods (NRs) of Ce0.9Ti0.1O2 (CT-NR) and Au-deposited CT-NR (Au-CT-NR) photocatalysts with a sacrificial agent (Fe3+) and in plain water in one sun condition, direct sunlight and with lambda \>= 455 nm. Probably the highest 0 2 yield of 11 mmol/h.g was observed with Au-CT-NR thin film in plain water in direct sunlight, with no sacrificial agent or applied potential. Photoelectrochemical measurements demonstrate a marked reduction in oxidation onset potential of Au-CT-NR by 150 mV with stable photocurrent (0.75 mA/cm(2)), compared to CT-NR (0.23 mA/cm(2)), indicating the operative of plasmon-induced resonant energy transfer (PIRET) process. Effective electron quenching by nanogold and hence low recombination in the depletion region is a critical step for the observation of a high rate of oxygen evolution. In addition to this, a predominant change in the nature of the valence band from O-2p dominated on CeO2 to Ce-4f dominated with CT-NR (due to Ti4+ introduction in CeO2), the efficient light absorption of photocatalysts in thin-film form, functional and effective PIRET process, and facile E-F alignment, enhances the oxygen evolution with Au-CT-NR in direct sunlight and make it highly sustainable. A possible mechanism of water oxidation is proposed from the observed experimental findings.

}, keywords = {ceria, Electronic integration, Photocatalysis, thin film, water splitting}, issn = {0974-3626}, doi = {10.1007/s12039-022-02055-z}, author = {Dubey, Anjani and Mishra, Abhaya Kumar and Negi, Sanjay Singh and Gopinath, Chinnakonda S.} } @article {48980, title = {Facile one-pot synthesis of Cu x O/TiO2 photocatalysts by regulating Cu oxidation state for efficient solar H2 production}, journal = {ACS Applied Energy Materials }, volume = {7}, year = {2023}, month = {DEC }, pages = {104-116}, type = {Article}, abstract = {

Development of highly efficient CuxO/TiO2 photocatalysts by regulating the oxidation state of Cu exclusively in either single or mixed oxidation state(s) is desirable but difficult to achieve without employing any external reagents. The present work describes a one-pot synthesis strategy to obtain CuxO/TiO2 photocatalysts with Cu in +1 and/or +2 by using a suitable combination of ethylene diamine tetra acetic acid (EDTA) and ethylene diamine, carefully varying the Cu content, and heat treatment process. CuxO/TiO2 nanocomposite catalysts were characterized thoroughly by physicochemical methods. Textural analysis indicates a high dispersion of CuxO on porous TiO2 with p-n heterojunctions between them in CuxO/TiO2 catalysts. UV-visible spectral analysis suggests the presence of CuxO on TiO2 with significantly extended absorption from the UV to the visible region. X-ray photoelectron spectroscopy (XPS) analysis indicates a strong synergetic interaction between TiO2 and CuxO due to the comparable CB potential and p-n heterojunction at the interface among them. Photoelectrochemical studies demonstrate excellent charge-carrier separation efficiency, low charge-transfer resistance, and high double-layer capacitance with Cu2O/TiO2 photocatalysts. Photocatalytic efficacy of a CuxO/TiO2 nanocomposite in thin-film form has been demonstrated for solar hydrogen generation in sunlight. The incorporation of Cu+ in TiO2 largely improves the H-2 production, and all of the CuxO/TiO2 nanocomposites in thin-film form exhibited higher efficiency compared to their particulate/suspension counterpart. Among the composite catalysts, TiCu-1 in thin-film form, with Cu exclusively in +1 oxidation state, exhibited a high hydrogen production rate of 7.06 mmol/hg, which is 6 times higher than its suspension counterpart; also catalysts containing mixed Cu-oxidation states exhibited about 60-70\% activity as that of TiCu-1. The superior performance of Cu2O/TiO2 nanocomposites in thin-film form was due to their enhanced light harvesting ability, high mass transfer rate, and easy accessibility of the reactant species to the active sites.

}, keywords = {heterojunction, Photocatalysis, Solar hydrogen, thin film, titania}, issn = {2574-0962}, doi = {10.1021/acsaem.3c02272}, author = {Rajendran, Sivaraj and Mani, Sunesh S. and Nivedhitha, Thazhath R. and Asoka, Anantha Krishnan and Arun, Pushkaran S. and Mathew, Thomas and Gopinath, Chinnakonda S.} } @article {49365, title = {Fuel-influenced nanorod-to-nanosphere transformation of vanadium-doped ZnO and its performance in dye-sensitized solar cells}, journal = {NEW JOURNAL OF CHEMISTRY}, volume = {48}, year = {2024}, month = {NOV }, pages = {19175-19187}, keywords = {Nanoparticles, Nanowires, Photoanode, Thin-films}, issn = {1144-0546}, doi = {10.1039/d4nj03589e}, author = {Kuppusamy, Sasikumar and Mohan, Theanmozhi and Gnana Kumar, G. and Gopinath, Chinnakonda S. and Saha, Arindam and Michael, Robin Jude Vimal} }