An electron deficiency strategy for enhancing hydrogen evolution on CoP nano-electrocatalysts

Optimizing the hydrogen adsorption on electrodes is one of the most effective strategies to promote the hydrogen evolution reaction (HER). In recent years, cobalt phosphides (CoP) have been identified as a promising catalyst for HER in acid. However, the hydrogen adsorption on CoP is strong and a considerable overpotential has to be applied to enable HER. Here, we report a strategy to weaken the hydrogen adsorption on CoP through an electron deficiency in CoP induced by Au@CoP core/shell structure. A weakened hydrogen adsorption is confirmed by the density functional theory (DFT) calculation. Au@CoP gave an overpotential (η) of 160 mV at the current density of 1 mA cm−2CoP, which is about 50 mV less than pure CoP. It also exhibited a turn-over frequency (TOF) value of 0.68 s−1 per active site at η = 150 mV, which is more than 4 times higher than CoP. The strategy reported here holds potential to be extended to other electrodes for optimizing their hydrogen adsorption for HER.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore