Electroactivity of Hydrogen Oxidation Reaction on Mixed‐Phase Pt x Pd 1‐x @SnO 2 /C Catalyst in Alkaline Electrolyte

ABSTRACT Sluggish hydrogen oxidation reaction (HOR) kinetics at the anode of alkaline anion‐exchange membrane fuel cells limit their widespread applications. In this study, a new type of Pt x Pd 1‐x @SnO 2 /C catalyst was designed for alkaline HOR. The electrochemical HOR kinetics was explored by potentiodynamic and electrochemical impedance spectroscopy methods supported by density functional theory (DFT). The composition of Pt and Pd in the catalyst was optimized and the highest HOR exchange current density ( j 0 ) of 0.414 mA cm −2 Pt+Pd was measured using Pt 0.5 Pd 0.5 @SnO 2 /C catalyst. This value is 4.3× and 15.9 × higher than commercial Pt/C and Pd/C, respectively, measured under same conditions. DFT calculations were performed to identify possible adsorption sites for H 2 and their adsorption energies, changes in H adsorption Gibbs free energy, overpotential (36 mV), and electronic properties. Based on electrochemical CO stripping experiments and DFT Bader charge distribution, the enhanced HOR activity is attributed to the oxophilic effect provided by SnO 2 and electron transfer from metals (Pd and Pt) to the SnO 2 cluster. An H 2 ‐O 2 AEMFC assembled with Pt 0.5 Pd 0.5 @SnO 2 /C anode showed the practical application in device.