02702nas a2200337 4500008004100000022001400041245012800055210006900183260007300252300001200325490000700337520156900344653003201913653002601945653001601971653001701987653001402004653001302018653001702031653002302048653001702071653003002088653002002118653000802138100001302146700001502159700001802174700001502192700003002207856012702237 2005 eng d a0926-337300aIn situ XPS investigations of Cu1-xNixZnAl-mixed metal oxide catalysts used in the oxidative steam reforming of bio-ethanol0 aIn situ XPS investigations of Cu1xNixZnAlmixed metal oxide catal aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB a287-2990 v553 a

A series of CuNiZnAl-multicomponent mixed metal oxide catalysts with various Cu/Ni ratios were prepared by the thermal decomposition of Cu1-xNixZnAl-hydrotalcite-like precursors and tested for oxidative steam reforming of bio-ethanol. Dehydrogenation of EtOH to CH3CHO is favored by Cu-rich catalyst. Introduction of Ni leads to C-C bond rupture and producing CO, CO2 and CH4. H-2 yield (selectivity) varied between 2.6-3.0 mol/mol of ethanol converted (50-55%) for all catalysts at 300 degreesC. The above catalysts were subjected to in situ XPS studies to understand the nature of active species involved in the catalytic reaction. Core level and valence band XPS as well as Auger electron spectroscopy revealed the existence of Cu2+, Ni2+ and Zn2+ ions on calcined materials. Upon in situ reduction at reactions temperatures, the Cu2+ was fully reduced to Cu-0. while Ni2+ and Zn2+ were partially reduced to Ni-0 and Zn-0, respectively. On reduction, the nature of ZnO on Cu-rich catalyst changes from crystalline to amorphous, relatively inert and highly stabilized electronically. Relative concentration of the Ni-0 and Zn-0 increases upon reduction with decreasing Cu-content. Valence band results demonstrated that the overlap between 3d bands of Cu and Ni was marginal on calcined materials, and no overlap due to metallic clusters formation after reduction. Nonetheless, the density of states at Fermi level increases dramatically for Ni-rich catalysts and likely this influences the product selectivity. (C) 2004 Elsevier B.V. All rights reserved.

10aauger electron spectroscopy10aAutothermal reforming10aBio-ethanol10acopper oxide10afuel cell10aHydrogen10ahydrotalcite10amixed metal oxides10anickel oxide10aoxidative steam reforming10aSteam reforming10aXPS1 aVelu, S.1 aSuzuki, K.1 aVijayaraj, M.1 aBarman, S.1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/situ-xps-investigations-cu1-xnixznal-mixed-metal-oxide-catalysts-used-oxidative-steam-002674nas a2200265 4500008004100000022001400041245011200055210006900167260007700236300001200313490000600325520169700331653002802028653001302056653002502069653001902094653002002113100003302133700002502166700001602191700001502207700002702222700003002249856012902279 2014 eng d a1867-388000aDisordered mesoporous TiO2-xNx+Nano-Au: an electronically integrated nanocomposite for solar H-2 generation0 aDisordered mesoporous TiO2xNxNanoAu an electronically integrated aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcFEB a522-5300 v63 a

We report on H-2 generation by photocatalysis driven by simulated white light by electronically integrated Au nanoparticles with multifunctional, disordered mesoporous TiO2-xNx (Au-NT) nanocomposites. Solar H-2 generation (1.5 mmolh(-1)g(-1)) from aqueous methanol has been demonstrated with Au-NT nanocomposites. The water splitting activity of Au-NT is attributed to the 21.1 ps lifetime of charge carriers observed from fluorescence lifetime measurements, which indicates a high electron-injection efficiency from nano-Au to the conduction band of TiO2, and hence charge separation as well as utilization. This is directly supported by the observation of a high photoluminescence emission intensity with Au-NT that highlights the energy transfer from nano-Au to TiO2. The p-n heterojunction observed between the Au (001) and TiO2 (101) facets helps to-wards the higher charge separation and their utilization. A low mesochannel depth (< 10 nm) associated with disordered mesoporous TiO2-xNx helps the charge carriers to move towards the surface for redox reactions and hence charge utilization. Visible-light absorption, as a result of the surface plasmon resonance of nano-Au, is observed in a broad range between 500 and 750 nm, which helps in harvesting visible-light photons. Finally, electronically integrated nano-Au with TiO2-xNx in Au-NT is evident from Raman and X-ray photoelectron spectroscopy measurements. All of these factors help to achieve a high rate of H-2 production. It is likely that a higher rate of H-2 production than that reported here is feasible by strategically locating Au clusters in porous TiO2 to generate hot spots through electronic integration.

10aheterogeneous catalysis10aHydrogen10amesoporous materials10aphotochemistry10awater splitting1 aSivaranjani, Kumarsrinivasan1 aRajaambal, Sivaraman1 aDas, Tanmay1 aRoy, Kanak1 aBhattacharyya, Somnath1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/disordered-mesoporous-tio2-xnxnano-au-electronically-integrated-nanocomposite-solar-h-2-002870nas a2200265 4500008004100000022001400041245014500055210006900200260007100269300001400340490000600354520191100360653001202271653002802283653001302311653001402324653001902338653001702357653001402374653002502388100001502413700001602428700003002444856013002474 2014 eng d a2155-543500aTowards a sustainable and near ambient DeNO(x) under lean burn conditions: a revisit to no reduction on virgin and modified pd(111) surfaces0 aTowards a sustainable and near ambient DeNOx under lean burn con a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN a1801-18110 v43 a

Catalytic conversion of NO in the presence of H-2 and O-2 has been studied on Pd(111) surfaces, by using a molecular beam instrument with mass spectrometry detection, as a function of temperature and reactants composition. N-2 and H2O are the major products observed, along with NH3 and N2O minor products under all conditions studied. Particular attention has been paid to the influence of O-2 addition toward NO dissociation. Although O-2-rich compositions were found to inhibit the deNO(x) activity of the Pd catalyst, some enhancement in NO reduction to N-2 was also observed up to a certain O-2 content. The reason for this behavior was determined to be the effective consumption of the H-2 in the mixture by the added O-2 and O atoms from NO dissociation. NO was proven to compete favorably against O-2 for the consumption of H-2, especially <= 550 K, to produce N-2 and H2O. Compared with other elementary reaction steps, a slow decay observed with the 2H + 0 -> H2O step under SS beam oscillation conditions demonstrates its contribution to the rate-limiting nature of the overall reaction. Pd(111) surfaces modified with O atoms in the subsurface (Md-Pd(111)) induces steady-state NO reduction at near-ambient temperatures (325 K) and opens up a possibility to achieve room temperature emission control. A 50% increase in the reaction rates was observed at the reaction maximum on Md-Pd(111), as compared with virgin surfaces. Oxygen adsorption is severely limited below 400 K, and effective NO + H-2 reaction occurs on Md-Pd(111) surfaces. Valence band photoemission with a UV light source (He I) under different oxygen pressures with APPES clearly identified the characteristics of the Md-Pd(111) surfaces and PdO. The electron-deficient or cationic nature of Md-Pd(111) surfaces enhances the NO dissociation and inhibits oxygen chemisorption <= 400 K under lean-burn conditions.

10adeNO(x)10aheterogeneous catalysis10aHydrogen10alean burn10amolecular beam10anitric oxide10aPalladium10asurface modification1 aRoy, Kanak1 aJain, Ruchi1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/towards-sustainable-and-near-ambient-denox-under-lean-burn-conditions-revisit-no-reduction02506nas a2200253 4500008004100000022001400041245006900055210006800124260010200192300001000294490000800304520163300312653001301945653001701958653001901975653001601994653001802010653001802028653002002046100002502066700003302091700003002124856009802154 2015 eng d a0974-362600aRecent developments in solar H-2 generation from water splitting0 aRecent developments in solar H2 generation from water splitting aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACAD SCIENCEScJAN a33-470 v1273 a

Hydrogen production from water and sunlight through photocatalysis could become one of the channels, in the not-so-distant future, to meet a part of ever growing energy demands. However, accomplishing solar water splitting through semiconductor particulate photocatalysis seems to be the `Holy Grail' problem of science. In the present mini-review, some of the critical strategies of semiconductor photocatalysis are focused with the aim of enumerating underlying critical factors such as visible light harvesting, charge carrier separation, conduction and their utilization that determine the quantum efficiency. We attempted to bring out the essential requirements expected in a material for facile water splitting by explaining important and new designs contributed in the last decade. The newly emerged designs in semiconductor architecture employing nanoscience towards meeting the critical factors of facile photocatalysis are elucidated. The importance of band gap engineering is emphasized to utilize potential wide band gap semiconductors. Assistance of metal nanostructures and quantum dots to semiconductors attains vital importance as they are exuberant visible light harvesters and charge carrier amplifiers. Benevolent use of quantum dots in solar water splitting and photoelectrochemical water splitting provides scope to revolutionize the quantum efficiency by its multiple exciton generation features. A list of drawbacks and issues that hamper the much needed breakthrough in photocatalysis of water splitting is provided to invite attention to address them and move towards sustainable water splitting.

10aHydrogen10ananomaterial10aPhotocatalysis10aquantum dot10aSemiconductor10avisible light10awater splitting1 aRajaambal, Sivaraman1 aSivaranjani, Kumarsrinivasan1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/recent-developments-solar-h-2-generation-water-splitting-001740nas a2200241 4500008004100000022001400041245008300055210006900138260000800207300001200215490000600227520098000233653001301213653002201226653001301248653001901261653001701280100001601297700002101313700002001334700003001354856011401384 2020 eng d a2367-198X00aCu-Ni bimetal integrated TiO2 thin film for enhanced solar hydrogen generation0 aCuNi bimetal integrated TiO2 thin film for enhanced solar hydrog cMAY a19005570 v43 a

A series of non-noble Cu-Ni bimetallic catalysts is prepared with different molar proportions of metals. Of these bimetallic catalysts, 1 wt% is subsequently integrated with titania P25. The catalysts are evaluated for solar hydrogen generation under 1 sun condition in both the powder and thin film forms. All the photocatalysts in the thin film exhibit an 8-24 times higher hydrogen yield (HY) compared with the corresponding particulate counterpart. The highest HY (41.7 mmol h(-1) g(-1)) is demonstrated for the photocatalyst Cu-Ni/TiO2 (CNT; 1:1 = Cu:Ni) in the thin film form, which is 24 times higher than that with its powder counterpart (1.75 mmol h(-1) g(-1)) and exceeds the performance of other Cu-Ni/TiO2 compositions. This enhanced activity in the thin film can be ascribed to improved absorption of visible light and an effective separation of photogenerated charge carriers at the interface of Cu-Ni/TiO2 leading to better charge carrier utilization.

10abimetals10aenergy conversion10aHydrogen10aPhotocatalysis10asolar energy1 aTudu, Bijoy1 aNalajala, Naresh1 aSaikia, Pranjal1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/cu-ni-bimetal-integrated-tio2-thin-film-enhanced-solar-hydrogen-generation02522nas a2200265 4500008004100000022001400041245010300055210006900158260000900227300001600236490000600252520166000258653001501918653001301933653001601946653001701962653000901979653002001988100001602008700002102024700002902045700002002074700003002094856013202124 2021 eng d a2168-048500aRationally designed, efficient, and earth-abundant Ni-Fe cocatalysts for solar hydrogen generation0 aRationally designed efficient and earthabundant NiFe cocatalysts cOCT  a13915-139250 v93 aDeveloping highly efficient and affordable catalysts for solar hydrogen (H-2) generation is crucial, and employing a cocatalyst from earth-abundant elements has a critical role to play. In this context, different compositions of earth-abundant Ni-Fe alloy (1:1, 1:3, and 3:1) have been prepared by hydrothermal method; subsequently, 1 wt % of these Ni-Fe cocatalysts were integrated with TiO2-P25 and thoroughly characterized. The resultant catalysts have been evaluated for solar H-2 production, in powder and thin film forms, under one sun condition and in direct sunlight. Interestingly, all the catalysts in the thin film form exhibit superior hydrogen yield (HY), up to 27 times higher activity than its powder counterpart. Among the photocatalysts, Ni-Fe/TiO2 (3:1 = Ni/Fe; NFT31) composition exhibits the best HY in thin film (8.27 mmol.h(-1).g(-1)) and exceeds all other compositions of catalyst. It is also to be reported that HY measured for the powder form with 1 mg shows 3-17 times higher activity than that measured with 25 mg. This is mainly attributed to effective solar light absorption with a smaller amount of photocatalyst either spread over large area in a thin film form or well-dispersed in suspension forms. Furthermore, the enhanced activity obtained with Ni-Fe/TiO2 photocatalysts is also ascribed to strong electronic integration of Ni-Fe cocatalyst with TiO2 and higher performance obtained with a thin film is attributed to increased charge carrier generation and subsequent charge separation and effective utilization. A decrease in work function of TiO2 by 0.6 eV was observed after its integration with cocatalyst in NFT31.10aCocatalyst10aHydrogen10aNi-Fe alloy10asolar energy10aTiO210awater splitting1 aTudu, Bijoy1 aNalajala, Naresh1 aReddy, Kasala, Prabhakar1 aSaikia, Pranjal1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/rationally-designed-efficient-and-earth-abundant-ni-fe-cocatalysts-solar-hydrogen-generation