02314nas a2200241 4500008004100000022001400041245011900055210006900174260008900243300001200332490000800344520137100352653002601723653002801749653001901777653001401796653001201810653002501822100003201847700003201879700003001911856013101941 2009 eng d a0169-433200aElectronic decoupling of surface layers from bulk and its influence in oxidation catalysis: a molecular beam study0 aElectronic decoupling of surface layers from bulk and its influe aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbInst Phys; Indian Assoc Cutivat ScicOCT a443-4480 v2563 a

Interactions between oxygen and Pd-surfaces have important implications, especially towards oxidation reactions, and influence of subsurface oxygen to oxidation reactions is the focus of the present study. In our efforts to understand the above aspects, CO oxidation reactions have been carried out with mixed molecular beam (MB), consisting CO and O(2), on Pd(1 1 1) surfaces under a wide variety of conditions (T = 400-900 K, CO: O(2) = 7: 1 to 1: 10). A new aspect of the above reaction observed in the transient kinetics regime is the evidence for oxygen diffusion into Pd subsurface layers, and its significant influence towards CO oxidation at high temperatures (>= 600 K). Interesting information derived from the above studies is the necessity to fill up the subsurface layers with oxygen atoms to a threshold coverage (theta(O-sub)), above which the reactive CO adsorption occurs on the surface and simultaneous CO(2) production begins. There is also a significant time delay (G) observed between the onset of oxygen adsorption and CO adsorption (and CO(2) production). Above studies suggest an electronic decoupling of oxygen covered surface and subsurface layers, which is slightly oxidized, from the metallic bulk, which induces CO adsorption at high temperatures and simultaneous oxidation to CO(2). (C) 2009 Elsevier B.V. All rights reserved.

10aElectronic decoupling10aheterogeneous catalysis10amolecular beam10aOxidation10aPd(111)10aSubsurface diffusion1 aThirunavukkarasu, Kandasamy1 aNagarajan, Sankaranarayanan1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/electronic-decoupling-surface-layers-bulk-and-its-influence-oxidation-catalysis-molecular-001619nas a2200229 4500008004100000022001400041245012400055210006900179260007700248300001000325490000600335520074600341653001501087653001301102653001401115653001401129653002101143100003001164700003201194700003201226856013101258 2009 eng d a1861-472800aKinetic evidence for the influence of subsurface oxygen on palladium surfaces towards CO oxidation at high temperatures0 aKinetic evidence for the influence of subsurface oxygen on palla aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcOCT a74-800 v43 a

Transient state kinetics of the catalytic oxidation of CO with 0, on Pd-surfaces has been measured under isothermal conditions by using a molecular beam approach. Systematic studies were carried out as a function of reaction temperature and CO+O(2) composition. With sufficient kinetic evidence, we have demonstrated the positive influence of subsurface oxygen towards CO-adsorption and oxidation to CO, at high temperatures (600-900 K) on Pd-surfaces, and the likely electronic nature of the surface changes with oxygen in the subsurface. These studies also provide a direct proof for CO-adsorption with a significantly reactive sticking coefficient at high temperatures on Pd-surfaces exhibiting a significant subsurface O-coverage.

10aAdsorption10akinetics10aOxidation10aPalladium10asurface analysis1 aGopinath, Chinnakonda, S.1 aThirunavukkarasu, Kandasamy1 aNagarajan, Sankaranarayanan uhttps://library.ncl.res.in/content/kinetic-evidence-influence-subsurface-oxygen-palladium-surfaces-towards-co-oxidation-high-001985nas a2200253 4500008004100000022001400041245010300055210006900158260007700227300001400304490000600318520106600324653002001390653000901410653002801419653001401447653001001461100002601471700002901497700002601526700002601552700003001578856012301608 2014 eng d a1867-388000aRole of nanointerfaces in Cu- and Cu plus Au-based near-ambient-temperature CO oxidation catalysts0 aRole of nanointerfaces in Cu and Cu plus Aubased nearambienttemp aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcNOV a3116-31240 v63 a

Disordered mesoporous Cu-doped ceria-zirconia (Cu0.1Ce0.85Zr0.05O2), and gold deposited (Au/Cu0.1Ce0.85Zr0.05O2) catalysts were synthesized and evaluated for CO oxidation. Onset of CO oxidation activity, and 50% (100%) CO2 formation occurs at room temperature (RT), and 77 (120)degrees C, respectively, with Cu0.1Ce0.85Zr0.05O2. A small amount of gold on Cu0.1Ce0.85Zr0.05O2 induces the sustainable oxidation catalysis around RT. Onset of copper reduction temperature decreases from 110 degrees C on Cu0.1Ce0.85Zr0.05O2 to 48 degrees C with Au/Cu0.1Ce0.85Zr0.05O2, highlighting the direct interaction between Cu and Au through a Cu-Au interface. Au particles with a (00 1) facet deposit on an oxygen-deficient site of (111) facet of CeO2-ZrO2. Any decrease in surface Cu-content with increasing Au-content further supports the Au-Cu-Ce/Zr interface interactions. Nanointerfaces of Au clusters on Cu next to oxygen-deficient sites of CeO2-ZrO2 facilitate all the elementary steps of the CO + O-2 reaction to occur in close proximity at ambient conditions.

10acarbon monoxide10aGold10aheterogeneous catalysis10aOxidation10aredox1 aGnanakumar, Edwin, S.1 aNaik, Jarpla, Madhusudha1 aManikandan, Marimuthu1 aRaja, Thirumalaiswamy1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/role-nanointerfaces-cu-and-cu-plus-au-based-near-ambient-temperature-co-oxidation-001866nas a2200229 4500008004100000022001400041245008200055210006900137260007700206300001200283490000600295520102500301653002801326653001401354653003101368653002201399653002501421100003001446700001501476700003201491856011301523 2015 eng d a1867-388000aCan we shift and/or broaden the catalysis regime towards ambient temperature?0 aCan we shift andor broaden the catalysis regime towards ambient  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcFEB a588-5940 v73 a

An attempt was made to shift the temperature regime of oxidation catalysis towards ambient temperatures by employing surface modification (SM) as a handle. Systematic SM of Pd(111) was performed by O-atom diffusion into the subsurfaces. Virgin and modified Pd(111) catalysts were evaluated for CO oxidation. Typical CO poisoning observed on virgin surfaces was partially lifted, and ambient CO oxidation was observed on the modified surfaces. CO oxidation was followed by the molecular beam method and near-ambient pressure (NAP) photoelectron spectroscopy under different pressure regimes. UV valence band spectral analysis of the SM and the CO+O-2 reaction on modified Pd(111) surfaces under NAP conditions demonstrated changes in the electronic structures of the surfaces with a change in surface potential by 0.35eV and directly probed CO2 formation under the reaction conditions. Supported metal catalysts may be subjected to SM and evaluated for a shift in the catalysis regime for many different reactions.

10aheterogeneous catalysis10aOxidation10aphotoelectron spectroscopy10asurface chemistry10asurface modification1 aGopinath, Chinnakonda, S.1 aRoy, Kanak1 aNagarajan, Sankaranarayanan uhttps://library.ncl.res.in/content/can-we-shift-andor-broaden-catalysis-regime-towards-ambient-temperature-002461nas a2200253 4500008004100000022001400041245017300055210006900228260000900297300001600306490000600322520151900328653002801847653001801875653001401893653001901907653002501926100002101951700002701972700002301999700002502022700003002047856013002077 2021 eng d a2574-096200aAqueous methanol to formaldehyde and hydrogen on Pd/TiO2 by photocatalysis in direct sunlight: structure dependent activity of nano-Pd and atomic Pt-coated counterparts0 aAqueous methanol to formaldehyde and hydrogen on PdTiO2 by photo cNOV  a13347-133600 v43 aIn the present investigation, facet-controlled Pd nanoparticles with nanocube (Pd-NC) and truncated octahedron (Pd-TO) morphologies, and their counterparts with half-a-monolayer of atomic Pt coated (0.5 theta(Pt)-Pd-NC and 0.5 theta(Pt)-Pd-TO) surfaces were prepared. All of them were characterized and evaluated as cocatalyst after supporting them on commercial titania (P25) (Pd-NC/P25, Pd-TO/P25, 0.5 theta(Pt)-Pd-NC/P25, and 0.5 theta(Pt)-Pd-TO/P25) under direct sunlight and/or one sun conditions for the oxidation of methanol to formaldehyde along with solar hydrogen production. Pd-NC/P25 shows higher activity for hydrogen generation compared to Pd-TO/P25; however, activity reversal occurs with the above cocatalysts, but, after Pt-coating with further enhanced activity. The highest conversion of methanol (0.2 mu mol/h.mg) to 100% selective formaldehyde was observed with 0.5 theta(Pt)-Pd-TO/P25, while other catalysts show significantly lower methanol conversion in the following order: 0.5 theta(Pt)-Pd-TO/P25 > 0.5 theta(Pt)-Pd-NC/P25 > Pd-NC/P25 > Pd-TO/P25. Pt-coated on (111) facets of Pd-TO simulates the activity associated as that of Pt(111) facets and demonstrating the highest and facet dependent activity. The present study is truly in resonance with exploiting the surface properties for heterogeneous catalysis, and highlights that less than a monolayer of Pt is sufficient to simulate the activity as that of bulk Pt. It is worth exploring this concept to other metals and substrates too.10aheterogeneous catalysis10aNanomaterials10aOxidation10aPhotocatalysis10asurface modification1 aNalajala, Naresh1 aSalgaonkar, Kranti, N.1 aChauhan, Inderjeet1 aMekala, Siva, Prasad1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/aqueous-methanol-formaldehyde-and-hydrogen-pdtio2-photocatalysis-direct-sunlight-structure02213nas a2200241 4500008004100000022001400041245018400055210006900239260000800308490000700316520131500323653002201638653001801660653001401678653001901692653001901711100002701730700002101757700002101778700002001799700003001819856012201849 2023 eng d a1861-472800aSelective and generic photocatalytic oxidation of alcohol with Pd-TiO2 thin films: butanols to butanal/butanone with different morphologies of Pd and 0.5 theta(Pt)-Pd counterparts0 aSelective and generic photocatalytic oxidation of alcohol with P cMAR0 v183 a

The present study reports on the photocatalytic oxidation of butanols to butanal/butanone using thin film form of facet-dependent nano-Pd supported on commercial TiO2 under one-sun condition and demonstrates the generic nature. Pd-nanocube (Pd-NC(100)), Pd-truncated octahedron (Pd-TO (100) and (111)), polycrystalline (Pd-PC), and their counterparts with half-a-monolayer Pt-coated on Pd (0.5 theta(Pt)-Pd)) have been used as co-catalyst. A potentially scalable thin film form of Pd/TiO2 photocatalyst, prepared by drop-casting method, has been employed to study oxidation of n-butanol, 2-butanol, and iso-butanol to corresponding aldehyde/ketone. 100% selectivity is demonstrated to respective aldehyde/ketone with any catalyst used in the present study with varying degree of butanols conversion by NMR. 0.5 theta(Pt)-Pd-TO/TiO2 shows the highest conversion of 2-butanol to butanone (13.6% in 4 h). Continuous 10 h of reaction with the most active 0.5 theta(Pt)-Pd-TO/P25 catalyst demonstrates 31% conversion of 2-butanol to butanone, and catalyst recyclability has been demonstrated. The present protocol can be scalable to large scales to maximize the conversion in direct sunlight. Due to its generic nature, the current method can also be applied to many other alcohols and substrate molecules.

10aenergy conversion10aNanomaterials10aOxidation10aPhotocatalysis10aSustainability1 aSalgaonkar, Kranti, N.1 aKale, Sandip, R.1 aNalajala, Naresh1 aMansuri, Sayana1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/selective-and-generic-photocatalytic-oxidation-alcohol-pd-tio2-thin-films-butanols