02041nas a2200253 4500008004100000022001400041245015600055210006900211260007300280300001000353490000800363520108600371653001901457653003501476653001801511653000801529653000801537100002901545700003201574700001801606700002201624700001801646856012301664 2016 eng d a1381-116900aPhotocatalytic H-2 evolution from water-methanol mixtures on InGaO3(ZnO)(m) with an anisotropic layered structure modified with CuO and NiO cocatalysts0 aPhotocatalytic H2 evolution from watermethanol mixtures on InGaO aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a82-880 v4153 a

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.

10aInGaO3(ZnO)(m)10aphotocatalytic water splitting10avisible light10aXPS10aXRD1 aNarendranath, Soumya, B.1 aThekkeparambil, Saranya, V.1 aGeorge, Leena1 aThundiyil, Shibin1 aDevi, Nandini uhttps://library.ncl.res.in/content/photocatalytic-h-2-evolution-water-methanol-mixtures-ingao3znom-anisotropic-layered01762nas a2200181 4500008004100000022001400041245014300055210006900198260000900267300001600276490000700292520106900299100002201368700001801390700002401408700001801432856013001450 2020 eng d a1463-907600aRole of B site ions in bifunctional oxygen electrocatalysis: a structure-property correlation study on doped Ca(2)Fe(2)O(5)brownmillerites0 aRole of B site ions in bifunctional oxygen electrocatalysis a st cJUL  a15520-155270 v223 a

The role of B site doping with transition metals in brownmillerites, a perovskite related family of compounds, in bifunctional oxygen electrocatalysis,viz., simultaneous reduction and evolution reactions, is analysed. Ca2Fe1.9M0.1O5(M = Mn, Co, Ni, and Cu) is synthesised and structurally characterised by powder XRD and Rietveld refinement. Valence states of the surface B site ions are identified by X-ray photoelectron spectroscopy. Bifunctional oxygen electrochemistry is studied with the RDE and RRDE techniques and correlated with the structural and electronic parameters like oxygen non-stoichiometry and B site catalytic activity. Since the widely accepted electronic descriptors like e(g)filling may not be sufficient for explaining the bifunctional activity, B site electron donating capability as well as the extent of oxygen vacancies enhancing O(2)adsorption is also considered. Such structural parameters are also found to influence both the ORR and OER and based on this, Ni doping is proposed as advantageous for the bifunctional activity.

1 aThundiyil, Shibin1 aVinod, C., P.1 aKurungot, Sreekumar1 aDevi, Nandini uhttps://library.ncl.res.in/content/role-b-site-ions-bifunctional-oxygen-electrocatalysis-structure-property-correlation-study02015nas a2200217 4500008004100000022001400041245012400055210006900179260000800248300001200256490000700268520127400275653000901549653002201558653000801580653001301588100002201601700002401623700001801647856013201665 2021 eng d a1944-824400aEfficient electrochemical oxygen reduction to hydrogen peroxide by transition metal-doped silicate Sr0.7Na0.3SiO3-delta0 aEfficient electrochemical oxygen reduction to hydrogen peroxide  cJAN a382-3900 v133 a

Electrochemical oxygen reduction in a selective two-electron pathway is an efficient method for onsite production of H2O2. State of the art noble metal-based catalysts will be prohibitive for widespread applications, and hence earth-abundant oxide-based systems are most desired. Here we report transition metal (Mn, Fe, Ni, Cu)-doped silicates, Sr0.7Na0.3SiO3-delta, as potential electrocatalysts for oxygen reduction to H2O2 in alkaline conditions. These novel compounds are isostructural with the parent Sr0.7Na0.3SiO3-delta and crystallize in monoclinic structure with corner-shared SiO4 groups forming cyclic trimers. The presence of Na stabilizes O vacancies created on doping, and the transition metal ions provide catalytically active sites. Electrochemical parameters estimated from Tafel and Koutechy-Levich plots suggest a two-electron transfer mechanism, indicating peroxide formation. This is confirmed by the rotating ring disc electrode method, and peroxide selectivity and Faradaic efficiency are calculated to be in the range of 65-82% and 50-68%, respectively, in a potential window 0.3 to 0.6 V (vs RHE). Of all the dopants, Ni imparts the maximum selectivity and efficiency as well as highest rate of formation of H2O2 at 1.65 mu mol s(-1).

10aH2O210amixed metal oxide10aORR10asilicate1 aThundiyil, Shibin1 aKurungot, Sreekumar1 aDevi, Nandini uhttps://library.ncl.res.in/content/efficient-electrochemical-oxygen-reduction-hydrogen-peroxide-transition-metal-doped-silicate10229nas a2200157 4500008004100000245014200041210006900183260000800252300001200260490000800272520959800280100002209878700002409900700001809924856012909942 2021 eng d00aSynergistic effect of B site co-doping with Co and Ce in bifunctional oxygen electrocatalysis by oxygen deficient brownmillerite Ba2In2O50 aSynergistic effect of B site codoping with Co and Ce in bifuncti cSEP a494-5000 v3753 a

Specificity in oxygen reduction and evolution reactions is pivotal in bifunctional catalysts in advanced energy devices which are expected to be active in a wide potential window and stable in both electrochemically reducing and oxidising atmospheres. State of the art noble metal catalysts for these reactions are fraught with issues whereas, metal oxides are expected to be stable in large potential window and can be tuned to have better bifunctional activity. Catalytically active metals, redox centres, oxygen vacancies etc. are some of the features of structured oxides which can be exploited in oxygen electrocatalysis. Brownmillerite family of compounds with general formula, A2B2O5 has high concentrations of ordered oxygen vacancy in a layer and can be promising bifunctional oxygen electrocatalysts, by appropriate B site doping. Ba2In2O5 is a well-studied system for its oxide ion conductivity and proximity of active B sites to O vacancies provide good O adsorption sites which are catalytically active. Here, cobalt and cerium are co-doped in Ba2In2O5, anticipating a synergistic effect of Ce(III)/Ce(IV) redox centre in ORR and Co activity in OER along with O vacancies providing adsorption sites. We have studied the structural changes associated with the doping by Rietveld refinement of the XRD patterns and correlated the structure to bifunctional oxygen electrocatalytic activity which is found to enhance on increasing the Co and Ce content.

1 aThundiyil, Shibin1 aKurungot, Sreekumar1 aDevi, Nandini uhttps://library.ncl.res.in/content/synergistic-effect-b-site-co-doping-co-and-ce-bifunctional-oxygen-electrocatalysis-oxygen01942nas a2200229 4500008004100000022001400041245012600055210006900181260000800250300001100258490000800269520113200277653001701409653002301426653002901449653002401478100002201502700002201524700002101546700001801567856012701585 2022 eng d a2468-823100aEffect of B site substitution in Gd2B2-xNiyO7-delta (B= Ti, Zr) ternary metal oxide catalysts in dry reforming of methane0 aEffect of B site substitution in Gd2B2xNiyO7delta B Ti Zr ternar cAPR a1122420 v5223 a

Structured catalysts are emerging as active and durable catalysts in dry reforming of methane due to their inherent characteristics like lattice insertion of active metals and consequent stability imparted. Here we report Ti and Zr substituted Gd2B2-xNiyO7-delta (B = Ti, Zr) catalysts synthesized by citrate gel method, which are characterized and tested for dry reforming of methane. Structure and Ni substitution has been confirmed by Rietveld refinement of powder XRD patterns and Raman analysis. TPR and CO2-TPD were performed to analyze the reducibility and effect of basic sites of catalysts in DRM activity. Ni doped Ti analogue shows stable and superior activity towards dry reforming of methane for 100 h. The in situ IR studies and XPS analysis confirmed the presence of surface hydroxyl species in this catalyst, which triggers the activation of CO2 and provides higher and durable activity in dry reforming reaction. Absence of any C formation in this catalyst after durability test indicates the mechanism of C gasification by the surface hydroxyl species enhancing stable activity for long durations.

10aA(2)B(2)O(7)10aCitrate gel method10aDry reforming of methane10aTernary metal oxide1 aGhodke, Seema, R.1 aThundiyil, Shibin1 aDongapure, Pavan1 aDevi, Nandini uhttps://library.ncl.res.in/content/effect-b-site-substitution-gd2b2-xniyo7-delta-b-ti-zr-ternary-metal-oxide-catalysts-dry01783nas a2200229 4500008004100000245010400041210006900145260000800214300001500222490000600237520097200243653001901215653001601234653003501250653002601285653003001311100002201341700002401363700002401387700001801411856012401429 2022 eng d00aTuning of oxygen reduction pathways through structural variation in transition metal-doped Ba2In2O50 aTuning of oxygen reduction pathways through structural variation cJAN ae2021011630 v93 aAbstract Oxygen reduction reaction (ORR) can take place either through a two-electron pathway to form H2O2 or through a four-electron pathway to form H2O. Both the reactions are important in the respective fields, viz., H2O2 production as well as fuel cell technology, and rational design of catalysts is mandatory to acquire high energy efficiency in both cases. Here, we report the structure-electrochemical property correlation of a series of perovskite related brownmillerite compounds, Ba2In0.75M0.25O5 (M=Mn/Fe/Co/Ni/Cu), synthesized by solid-state method. On transition metal doping, octahedral distortions were observed, and the highly disordered material tends to follow the 4e transfer mechanism. More symmetrical structures followed the 2e pathway to form H2O2 as the product with high peroxide selectivity. The distortion in the octahedral arrangement can be a descriptor to finetune the selectivity of the catalysts towards the 2e and 4e pathways of ORR.10abrownmillerite10aDescriptors10aElectrochemical H2O2 synthesis10aOctahedral distortion10aoxygen reduction reaction1 aThundiyil, Shibin1 aPandikassala, Ajmal1 aKurungot, Sreekumar1 aDevi, Nandini uhttps://library.ncl.res.in/content/tuning-oxygen-reduction-pathways-through-structural-variation-transition-metal-doped01739nas a2200253 4500008004100000022001400041245012800055210006900183260000900252490000700261520089200268653000901160653000801169653001501177653001301192653002601205100002101231700002101252700002201273700001601295700002901311700001801340856012701358 2023 eng d a1867-388000aMechanistic insights into near ambient pressure activity of intermetallic NiZn/TiO2 catalyst for CO2 conversion to methanol0 aMechanistic insights into near ambient pressure activity of inte cJAN 0 v153 a

Ni-Zn pair is predicted through descriptor-based studies to be conducive for CO2 hydrogenation. In this study, NiZn (1 : 1) intermetallics supported on TiO2 is identified as a potential candidate for near ambient pressure activity. The effect of reduction temperature on the catalyst textural properties as well as on CO2 to methanol reduction are explored. Structural and microscopic studies provide clear evidence of phase evolution of NiZn alloy with increasing reduction temperatures, along with phase variations of Zn based oxides. Interface between NiZn intermetallics and ZnO nanoparticles observed at reduction temperature of 550 degrees C, seems to play a crucial role in making this system most active and selective to methanol. In addition, in-situ IR studies provide mechanistic insights and indicates the formation of methanolic species even at ambient pressure.

10aCCUS10aCO210aIn-situ IR10aMethanol10anear ambient pressure1 aDongapure, Pavan1 aTekawadia, Jyoti1 aThundiyil, Shibin1 aCaha, Ihsan1 aDeepak, Francis, Leonard1 aDevi, Nandini uhttps://library.ncl.res.in/content/mechanistic-insights-near-ambient-pressure-activity-intermetallic-nizntio2-catalyst-co2