A density functional theory study of the water–gas shift reaction promoted by Pt-based catalysts

The water–gas shift reaction (WGSR) promoted by several Pt-based catalysts Pt3M (M = Pt, Cu, Mo, Ni, Rh) has been investigated with density functional theory calculations in the present work. The reaction mechanism is explored along an associative carboxylate-formate mechanism. The catalytic cycle processes, in all cases, involve three sequential elementary steps: the rupture of the O–H bond in H2O, the formation of OCOH, and the formate dissociation and CO2 desorption. According to thermodynamics results, the energy barriers in path I on all clusters are lower than those of in path II and path III, indicating that WGSR prefers to occur when H2O and CO2 adsorb on the same Pt atom. Pt3Cu and Pt3Rh bimetallic clusters exhibit superior catalytic activity for WGS reaction among all those investigated clusters. The present theoretical study enriches our understanding of the WGSR promoted by Pt-based catalysts.