02045nas a2200337 4500008004100000022001400041245014400055210006900199260000900268300001100277490000800288520095100296653001401247653001401261653001901275653000901294653001601303100002101319700001801340700001701358700002301375700002601398700002401424700002101448700001701469700002001486700003001506700002301536700001701559856013101576 2021 eng d a0926-860X00aIn-situ experimental and computational approach to investigate the nature of active site in low-temperature CO-PROX over CuOx-CeO2 catalyst0 aInsitu experimental and computational approach to investigate th cAUG  a1183050 v6243 aPreferential oxidation (PROX) of carbon monoxide (CO) in presence of excess hydrogen is a necessity to prevent poisoning of the Pt-anode by CO in PEMFCs (Polymer Electrolyte Membrane Fuel Cell). A highly active catalyst, 5 wt% Cu-CeO2 showed 100 % CO conversion at 65 degrees C without any undesirable oxidation of H-2. The catalyst showed no deactivation even after 100 h on stream, making it viable for practical fuel cell application. Operando EPR in the PROX reaction condition revealed highly dispersed mixed valent cations with oxygen vacancies, responsible for the low-temperature PROX activity. At the active site, both Cu and Ce ions were shown to reversibly change their valence states to facilitate the abstraction of bridging lattice oxygen for CO oxidation to CO2. This surface oxygen mediated CO oxidation was found to be much faster than that of H-2 to H2O, which could explain the complete selectivity of oxygen for CO2 formation.10aCuOx-CeO210ainterface10aOxygen vacancy10aPROX10aSynergistic1 aAdak, Shubhadeep1 aRabeah, Jabor1 aRanjan, Ravi1 aKhan, Tuhin, Suvra1 aPoddar, Mukesh, Kumar1 aGupta, Rishi, Kumar1 aSasaki, Takehiko1 aKumar, Sagar1 aBordoloi, Ankur1 aGopinath, Chinnakonda, S.1 aBruckner, Angelika1 aBal, Rajaram uhttps://library.ncl.res.in/content/situ-experimental-and-computational-approach-investigate-nature-active-site-low-temperature02213nas a2200313 4500008004100000022001400041245014500055210006900200260000800269300001600277490000700293520116000300653001701460653003401477653001901511653002801530653002301558653001901581100002801600700001301628700001701641700001901658700001901677700002501696700002001721700001801741700001401759856012601773 2022 eng d a2155-543500aBoosting electrochemical CO2 reduction to methane via tuning oxygen vacancy concentration and surface termination on a copper/ceria catalyst0 aBoosting electrochemical CO2 reduction to methane via tuning oxy cSEP a10973-109830 v123 a

Metal oxides are a promising material for designing highly active and selective catalysts for the electrochemical reduction of carbon dioxide (CO2RR). Here, we designed a Cu/ceria catalyst with high selectivity of methane production at single-atomic Cu active sites. Using this, we report favorable design concepts that push the product selectivity of methane formation by combining detailed structural analysis, density functional theory (DFT), in situ Raman spectroscopy, and electrochemical measurements. We demonstrate that a higher concentration of oxygen vacancies on the catalyst surface, resulting from more available Cu+ sites, enables high selectivity for methane formation during CO2RR and can be controlled by the calcination temperature. The DFT calculation and in situ Raman studies indicate that pH controls the surface termination; a more alkaline pH generates hydroxylated surface motifs with more active sites for the hydrogen evolution reaction. These findings provide insights into designing an efficient metal oxide electrocatalyst by controlling the atomic structure via the reaction environment and synthesis conditions.

10acopper-ceria10aelectrochemical CO2 reduction10aelectrolyte pH10agas diffusion electrode10amethane production10aOxygen vacancy1 aPatra, Kshirodra, Kumar1 aLiu, Zhu1 aLee, Hojeong1 aHong, Seungwon1 aSong, Hakhyeon1 aAbbas, Hafiz, Ghulam1 aKwon, Youngkook1 aRinge, Stefan1 aOh, Jihun uhttps://library.ncl.res.in/content/boosting-electrochemical-co2-reduction-methane-tuning-oxygen-vacancy-concentration-and02754nas a2200253 4500008004100000022001400041245014800055210006900203260000800272300001400280490000700294520185500301653002802156653001902184653003102203653000902234653001802243100002302261700001702284700001702301700002602318700003002344856012602374 2022 eng d a2168-048500aSustainable CO2 reduction on in (2)O(3 )with exclusive CO selectivity: catalysis and in situ valence band photoelectron spectral investigations0 aSustainable CO2 reduction on in 2O3 with exclusive CO selectivit cMAR a3521-35310 v103 a

This study demonstrates a sustainable catalytic CO2 conversion to near 100% CO selectivity at ambient pressure on In2O3. Critically, high CO yield could be observed at the cost of undesired methanation, using a lower than stoichiometric amount of hydrogen in the feed; 1:1 and 1:0.67 CO2:H-2 ratios exhibit 98-99.6% CO selectivity with 25-38% CO2 conversion between 773 and 873 K. CO2 and H-2 conversion under steady-state conditions at 773-873 K suggests a 1:1 ratio of adsorbed reactants (with 1:0.67 CO2:H-2 feed) on the catalyst surface, underscoring the presence of an ideal reactant composition for the reverse water-gas shift reaction, while H-2-rich feed compositions show the H-2-dominated surface. Surface electronic structure changes, under near-operating conditions, were explored with near ambient pressure photoelectron spectroscopy (NAPPES), and the interesting findings are as follows: (a) A shift in the valence band to lower binding energy, up to 0.6 eV, was observed because of electron filling at high temperatures. (b) An observation of heterogeneous nature of the catalyst surface under NAPPES measurement conditions is attributed to the generation of active oxygen vacancy (O-v) sites, which in turn changes the work function of In2O3. (c) The above changes are found to be reversible, when the reaction was stopped. Vibrational features of the reactant molecules were observed to be broadened in the active temperature window of the catalyst supporting the heterogeneous character of the catalyst surface because of dynamic O-v generation. By optimizing gas hourly space velocity, CO2:H-2 ratio, and reaction temperature, exclusive CO selectivity is possible with a H-2:CO2 ratio of similar to 0.67, which will avoid the product separation stage altogether, while minimizing the expensive H-2 in the reactant feed.

10aheterogeneous catalysis10aOxygen vacancy10aphotoelectron spectroscopy10aRWGS10aWork function1 aMhamane, Nitin, B.1 aChetry, Sibo1 aRanjan, Ravi1 aRaja, Thirumalaiswamy1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/sustainable-co2-reduction-2o3-exclusive-co-selectivity-catalysis-and-situ-valence-band02525nas a2200289 4500008004100000245010200041210006900143260000900212300001400221490000600235520159000241653001701831653001401848653001401862653002101876653002101897653001901918653001501937653002701952100002201979700001902001700002302020700001802043700002202061700002002083856013202103 2024 eng d00aDurable and stable bifunctional Co3O4-based nanocatalyst for oxygen reduction/evolution reactions0 aDurable and stable bifunctional Co3O4based nanocatalyst for oxyg cFEB  a3620-36300 v73 a

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are recognized as the core reaction processes in regenerative energy storage and conversion systems. The design of cost-effective and high-performance bifunctional ORR/OER electrocatalysts (ECs) is very important for their substantial commercialization. Herein, sponge-like Co3O4 nanoparticles anchored on carbon (Sp-Co3O4/C) are successfully fabricated by a facile two-step solvothermal strategy for ORR/OER in an alkaline electrolyte. The Sp-Co3O4/C EC exhibits promising bifunctional ORR/OER activity with ORR onset potential (E onset = 0.88 V vs RHE), half-wave potential (E (1/2) = 0.75 V), limiting current density (j = -6.60 mA cm(-2)), OER onset potential (E-onset = 1.26 V), and OER overpotential for 10% energy conversion (eta(10) = 0.38 V) in 0.1 M KOH. It demonstrates a significantly lower reversibility index (Delta E = E- j10 - E 1/2 = 0.86 V), comparable to standard Pt/C and RuO2 ECs. The superior ORR/OER performances of Sp-Co3O4/C EC can be ascribed to the synergistic contribution of a high electrochemically active surface area (48.33 m(2) g(-1)), BET surface area (131 m(2) g(-1)), the rich interfacial structure of the crystal facets (111), (220), and (311), and the abundant oxygen vacancies in the sponge-like morphology. Besides the methanol tolerance, accelerated durability and chronoamperometric test established excellent durability and stability in the electrocatalytic operation. This work offers insight into the development of high-performance ORR/OER ECs. [GRAPHICS]

10abifunctional10afuel cell10ainterface10aoxygen evolution10aoxygen reduction10aOxygen vacancy10aSp-Co3O4/C10asponge-like morphology1 aChutia, Bhugendra1 aChetry, Rashmi1 aRao, Komateedi, N.1 aSingh, Nittan1 aSudarsanam, Putla1 aBharali, Pankaj uhttps://library.ncl.res.in/content/durable-and-stable-bifunctional-co3o4-based-nanocatalyst-oxygen-reductionevolution-reactions