02754nas 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<p>
	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.</p>
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-band