Computational screening of single-atom doped In 2 O 3 catalysts for the reverse water gas shift reaction.

The reverse water gas shift (RWGS) reaction is an important method for converting carbon dioxide (CO 2 ) into valuable chemicals and fuels by hydrogenation. In this paper, the catalytic activity of single-atom metal-doped (M = Pt, Ir, Pd, Rh, Cu, Ni) indium oxide (c-In 2 O 3 ) catalysts in the cubic phase for the RWGS reaction was investigated using density functional theory (DFT) calculations. This was achieved by identifying metal sites, screening oxygen vacancies, followed by further calculating the energy barriers for the direct and indirect dissociation pathways of the RWGS reaction. Our results show that the single-atom dopant in the indium oxide lattice promotes the creation of oxygen vacancies on the In 2 O 3 surface, thereby facilitating the adsorption and activation of CO 2 by the oxide surface and initiating the subsequent RWGS reaction. Furthermore, we find that the oxygen vacancy (O V ) formation energy on the surface of the single-atom metal doped c-In 2 O 3 (111) surface can be used as a descriptor for CO 2 adsorption, and the higher the O V formation energy, the more stable the CO 2 adsorption structure is. The Cu/In 2 O 3 structure has relatively high energy barriers for both direct (1.92 eV) and indirect dissociation (2.09 eV) in the RWGS reaction, indicating its low RWGS reactivity. In contrast, the Ir/In 2 O 3 and Rh/In 2 O 3 structures are more conducive to the direct dissociation of CO 2 into CO, which may serve as more efficient RWGS catalysts. Furthermore, microkinetic simulations show that single atom metal doping to In 2 O 3 enhances CO 2 conversion, especially under high reaction temperatures, where the formation of oxygen vacancies is the limiting factor for CO 2 reactivity on the M/In 2 O 3 (M = Cu, Ir, Rh) models. Among these three single-atom catalysts, the Ir/In 2 O 3 model was predicted to have the best CO 2 reactivity at reaction temperatures above 573 K.