PtMo Bimetallic Catalysts with Controlled Compositions for Probing the Water-Gas Shift Reaction

Supported PtMo bimetallic catalysts of highly uniform composition were prepared using controlled surface reactions. These catalysts were applied to the Water-Gas Shift reaction to probe promoter properties and active sites. Molybdenum is shown to increase the rate of reaction by more than a factor of 1000. TOFs scale linearly with STEM/EDS-based estimates of surface Mo mole fraction, suggesting surface interfaces between Pt and Mo moieties are the active sites. This result is corroborated by preliminary microkinetic modeling experiments, which show that including interfacial steps qualitatively captures the experimentally observed promotion.