Boosting hydrogen production with ultralow working voltage by selenium vacancy‐enhanced ultrafine platinum–nickel nanowires

Abstract Defect engineering provides a highly potential way to yield exceptional catalytic performance. Herein, we first report the selenium (Se) vacancies‐decorated ultrafine platinum–nickel (PtNi‐Se v ) nanowires, as a bifunctional catalyst for the hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). The optimized PtNi‐Se v exhibits obvious enhancement for HER and MOR compared to PtNi nanowires. It displays merely an overpotential of 18.8 mV for alkaline HER and the outstanding MOR performance (3.51 A/mg Pt ). When applying in one symmetric overall water splitting electrolyzer coupling with HER and MOR, an ultralow working voltage of 0.637 V with 100% Faraday efficiency for hydrogen production was achieved at the current density of 10 mA/cm 2 . Further investigations reveal that the weakened hydrogen binding energy, strong OH binding as well as relative weak CO binding are responsible for the improved HER and MOR activities.