High-performance methanol electrolysis towards energy-saving hydrogen production: Using Cu2O-Cu decorated Ni2P nanoarray as bifunctional monolithic catalyst

Electrocatalytic methanol oxidation reaction (MOR) is a promising alternative approach to oxygen evolution reaction for efficient hydrogen production. However, developing highly efficient and cost-effective MOR cata-lysts, coupled with the cathodic hydrogen evolution reaction, is still a challenge. Herein, we used a Ni2P nanosheet array with Cu2O-Cu dendrites on nickel foam (Cu2O-Cu@Ni2P/NF) as an efficient and stable elec-trocatalyst for MOR, which attained a low potential of 1.41 V at 100 mA cm-2 and a small Tafel slope of 44.99 mV dec-1 with excellent stability for at least 24 h in 1.0 M KOH solution with 1.0 M methanol. In situ Raman spectroscopy reveals that Cu2O-Cu promotes the generation of the beta-NiOOH active phase, and converts to Cu(II)O under the electrolysis conditions. Furthermore, the methanol electrolysis cell utilizing Cu2O-Cu@Ni2P/NF as both the cathode and anode delivered a current density of 10 mA cm-2 at a low cell voltage of 1.40 V, and the cell voltage decreased by 210 mV at a current density of 100 mA cm-2 compared to water electrolysis. This work provides a new strategy to design the promising Ni-based phosphide as a bifunctional electrocatalyst in methanol electrolysis, enabling energy-saving H2 production.

Automated summary

Cu2O-Cu@Ni2P/NF is an efficient and stable electrocatalyst for MOR, achieving low potential, high stability, and low Tafel slope. In situ Raman spectroscopy reveals the promotion of beta-NiOOH active phase and conversion to Cu(II)O by Cu2O-Cu under electrolysis conditions. This catalyst as both the cathode and anode in a methanol electrolysis cell delivers lower voltage and higher current density compared to water electrolysis, indicating better performance.