The action of Pt in bimetallic Au–Pt/CeO2 catalyst for water–gas shift reaction

Bimetallic Au–M (M = Ni, Cu, Ag, Pt, and Pd) catalysts supported on CeO2 were prepared by step-by-step impregnation method for water–gas shift reaction. Among them Au–Pt/CeO2 catalyst shows the highest activity with 78% conversion of CO at 250 °C. The action of platinum in Au–Pt/CeO2 catalyst was investigated by means of X-ray diffraction, hydrogen temperature-programmed reduction, UV–vis diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy. It is found that the introduction of platinum in Au–Pt/CeO2 catalyst is responsible for the formation of partly oxidized gold species probably due to the interatomic charge transfer from Au 5d to Pt 5d band. The presence of both gold and platinum is beneficial to the reduction of ceria to Ce3+ species as well as the creation of oxygen vacancies and makes the average size of ceria smaller.