Huanqiao Song

PtIr alloy is considered as one of the most promising catalysts for ethanol electrooxidation due to its excellent C–C bond breaking and dehydrogenation abilities. However, a small amount of intermediate species produced by ethanol oxidation can still poison Pt, thereby affecting the stability of ethanol oxidation. Here, graphene supported PtIr nanoparticles (PtIr/GN) with a Pt: Ir atomic ratio of 3:1 is synthesized by a simple hydrothermal reduction and thermal annealing. The physicochemical analyses show that IrO ₂ is formed in situ in PtIr/GNs (O) during annealing and located adjacent to PtIr alloys. IrO ₂ and PtIr are evenly dispersed on GNs. The electrochemical results indicate that PtIr/GNs (O) has higher catalytic activity and stability for ethanol electrooxidation than PtIr/GNs. After 1000 voltammetric cycles, the peak current density for PtIr/GNs (O) is 2.5 times higher than that for PtIr/GNs. The outstanding electrochemical performance of PtIr/GNs (O) is derived from PtIr alloy that promotes the cleavage of the C–C bond and weakens the adsorption of Pt to intermediate species, IrO ₂ that improves the tolerance of Pt to CO-like species and enhances the structural stability of Pt, and PtIr alloy and IrO ₂ in adjacent positions that synergistically improve the stability of catalytic ethanol oxidation.