Indium oxide supported Pt–In alloy nanocluster catalysts with enhanced catalytic performance toward oxygen reduction reaction

Few currently applied carbon-supported metal cathode catalysts exhibit satisfactory durability under the harsh operation conditions of proton exchange membrane fuel cells. Herein we report for the first time a highly active In2O3 supported Pt–In alloy nanocluster (NC) catalyst (Pt–In/In2O3) toward oxygen reduction reaction, with small alloy NCs and a Pt content of 42 wt%, which exhibits obviously enhanced durability compared to currently applied carbon-supported Pt catalysts (Pt/C) and previously reported Pt NCs-based catalysts with a similar Pt content. The mass activity (MA) and specific activity (SA) over Pt–In/In2O3 are 0.32 A·mg−1Pt and 1.14 mA cm−2 at 0.9 V (vs. reversible hydrogen electrode (RHE)), respectively. Electron transfer from In to Pt in the alloy NCs occurs as confirmed by X-ray absorption measurements, which is an important cause of the high catalytic activity. After an accelerated aging test of 6000 potential cycles between 1.0 and 1.6 V, the MA loss over Pt–In/In2O3 is 3%, but that over Pt/C is 33%. The catalysts subjected to the aging test are characterized by transmission electron microscopy and X-ray diffraction to understand the extremely high durability.