Plasmon enhanced bifunctional electro-photo catalytic properties of Pt-Au/graphene composites for methanol oxidation and oxygen reduction reaction

A facile microwave assisted strategy was used to synthesize a series of Pt-Au/graphene (simplified as Pt-Au/GNs) catalysts with controllable Pt:Au ratios, in which K2PtCl4, HAuCl4 and graphite oxide were synchronously reduced using ethanol as a reducing agent. When a lower amount of Au is added, Pt and Au species form the heterostructure in Pt-Au/GNs composites, while as Au content increases further, excess Au particles are easy to agglomerate. Electrochemical experiments show that Pt-Au/GNs composites with lower Au content exhibit advantageous electrocatalytic performances and stability simultaneously towards methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). What's interesting is that, under simulated sunlight irradiation, Pt-Au/GNs composites with higher Au content behave superior electro-photo catalytic activities towards MOR and ORR, which is proportional to the size and content of Au. Comprehensive consideration of catalytic performance and cost, Pt-Au/GNs with the optimal Pt: Au ratio of 1:0.1 can serve as an efficient bifunctional electro-photo catalyst for catalyzing MOR and ORR.