Mechanism of methanol steam reforming on dual-atom catalysts of PtZn/TiO2 and PdZn/TiO2: Density functional theory studies

Abstract

Methanol steam reforming (MSR) is a potential method for producing hydrogen in situ. Finding excellent catalysts to improve reaction activity and CO2 selectivity is crucial. In this study, we used density functional theory (DFT) methods and the CP2K software package to investigate the mechanism of the MSR reaction on dual-atom catalysts of PtZn/TiO2 and PdZn/TiO2. The results showed that the most favorable reaction paths on these two catalysts are the same, namely CH3OH→CH3O→CH2O→CH2OOH→CHOOH→CHOO→CO2, in which the rate-determining step is CH2O+OH→CH2OOH with reaction barriers of 1.17 eV on PtZn/TiO2 and 1.29 eV on PdZn/TiO2, respectively. The reported PtZn/TiO2 and PdZn/TiO2 catalysts show improved activity compared to pure metal or corresponding alloy catalysts. The synergistic effect between metal atoms and the surface of TiO2 supports as well as the role of Zn atom doping were discussed. This work provides a new perspective for the design of atomic-level catalysts for the MSR reaction.