Optimizing Mo-C coordination for enhanced low-temperature water-gas shift activity over -MoC_1-x catalysts: An experimental and theoretical study

The low-temperature water-gas shift (WGS) reaction is an important industrial process for producing hydrogen and reducing carbon dioxide emissions. The alpha-MoC(1-x )catalysts have shown promising performance in WGS reactions, but their activities are highly dependent on the surface structure. In this study, we investigated the effect of surface Mo and C ordinations on the low-temperature WGS activity of Pt/alpha-MoC1-x catalysts using both experimental and theoretical methods. Our results reflected that as Mo: C ratio decreases, the surface free carbon and reduced number of Mo active sites led to a weakened electron transfer ability, resulting in poor catalytic activity. The 0.4% Pt/alpha-MoC1-x -50 catalyst displayed superior hydrogen production activity and low apparent activation energy (E-app = 58.5 kJ/mol) at low temperatures (100-200 C-degrees). Our density functional theory (DFT) calculations revealed that the high reactivity of the 0.4% Pt/alpha-MoC1-x -50 catalyst was due to the strong electron transfer capability and increased number of surface Mo active sites. This study provides new insights into the structure-activity relationship and stability of alpha-MoC(1-x )fcatalysts for the WGS reaction and lays the foundation for the design of WGS catalysts with high activity and stability at low temperature.