@article { ISI:000328952500024, title = {Investigations into variations in local cationic environment in layered oxide series InGaO3(ZnO)(m) (m=1-4)}, journal = {Dalton Transactions}, volume = {43}, number = {5}, year = {2014}, month = {NOV}, pages = {2120-2126}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Layered oxides of the series InGaO3(ZnO)(m) (m = 1-4) are interesting due to their structural anisotropy. Here, we report a comprehensive study of their structural details, focusing on the local cationic environment in bulk powder samples by MASNMR and EXAFS, which is hitherto not attempted. It is found that the Ga geometry varies gradually from pure pentacoordinated to a mixture of penta and tetracoordinated with increasing amounts of tetracoordination as we move across the series, contrary to previous reports suggesting exclusively trigonal bipyramidal coordination in all the compounds. A similar observation is also made in the case of Zn and structural evolution involving the dissolution of Ga in a ZnO4 tetrahedral network in a sandwich layer can be discerned, as the insulating ZnO layer size increases.

}, issn = {1477-9226}, doi = {10.1039/c3dt52011k}, author = {Narendranath, Soumya B. and Yadav, Ashok Kumar and Ajithkumar, Thalasseril G. and Bhattacharyya, Dibyendu and Jha, Shambhu Nath and Dey, Krishna K. and Raja, Thirumalaiswamy and Devi, R. Nandini} } @article { ISI:000340446300061, title = {Photocatalytic H-2 evolution from water-methanol system by anisotropic InFeO3(ZnO)(m) oxides without cocatalyst in visible light}, journal = {ACS Applied Materials \& Interfaces}, volume = {6}, number = {15}, year = {2014}, month = {AUG}, pages = {12321-12327}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

InFeO3(ZnO)(m), series of oxides are found to give unprecedented H-2 evolution from water-methanol mixtures without using any cocatalysts. This family of compounds has an anisotropically layered structure in which Zn/FeOn polyhedra are sandwiched between InO6 octahedral layers. Local structure characterization by X-ray absorption spectroscopy reveals that Zn coordination changes from pentacoordinated to tetrahedral geometry across the series, whereas Fe geometry remains trigonal bipyramidal in all the compounds. This peculiar structure is conducive for a spatial separation of photogenerated charges reducing recombination losses. Band gap energies calculated from absorption spectra indicate potential visible light activity, and this may be due to the orbital mixing of Fe 3d and O 2p as revealed by pre-edge features of X-ray absorption spectra. Band positions are also advantageously placed for a visible light H-2 generation and is indeed found to be the case in methanol-assisted water splitting with standardized hydrogen evolution of similar to 19.5 mmol g(-1) h(-1) for all the catalysts.

}, keywords = {anisotropic structure, H-2 evolution, InFeO3(ZnO)(m), layered oxide, photocatalytic water splitting}, issn = {1944-8244}, doi = {10.1021/am501976z}, author = {Narendranath, Soumya B. and Yadav, Ashok Kumar and Bhattacharyya, Dibyendu and Jha, Shambhu Nath and Devi, R. Nandini} } @article { ISI:000372684900009, title = {Photocatalytic H-2 evolution from water-methanol mixtures on InGaO3(ZnO)(m) with an anisotropic layered structure modified with CuO and NiO cocatalysts}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {415}, year = {2016}, month = {MAY}, pages = {82-88}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

InGaO3(ZnO)(m) series of oxides is found to be active for photocatalytic H-2 evolution from water-methanol mixtures. The structure of this series is highly anisotropic with InO6 octahedral layers sandwiching Ga/ZnOn polyhedra. The structural anisotropy in which the conducting layer is spatially separated from the charge generation sites may help in suppressing charge recombination and consequently enhance catalytic activity. The band gaps of the series obtained from absorption spectra are above 3.6 eV and hence they are not active under visible light irradiation. H-2 evolution is considerably enhanced under UV light on employing NiO as cocatalyst due to facile electron transfer from InGaO3(ZnO)(m). to NiO. However, when CuO is used as cocatalyst, visible light activity could be brought out. Due to the very low band gap of CuO, it can act as a sensitizer absorbing in visible light. The band positions become conducive for H-2 evolution due to band alignments consequent to electron accumulation in CuO conduction band. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {InGaO3(ZnO)(m), photocatalytic water splitting, visible light, XPS, XRD}, issn = {1381-1169}, doi = {10.1016/j.molcata.2016.01.018}, author = {Narendranath, Soumya B. and Thekkeparambil, Saranya V. and George, Leena and Thundiyil, Shibin and Devi, R. Nandini} }