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

Cu 2 O-Cu@Ni 2 P/NF electrode shows excellent MOR performance with a current density of 100 mA cm –2 at 1.41 V and a Tafel slope of 44.99 mV dec –1 in 1.0 M KOH solution containing 1.0 M methanol. Furthermore, the methanol electrolysis cell utilizing Cu 2 O-Cu@Ni 2 P/NF as both the cathode and anode delivers a current density of 10 mA cm −2 at a cell voltage of 1.40 V. In situ Raman spectroscopy unveils that Cu 2 O-Cu promotes the formation of β-NiOOH, and converts to Cu(II)O during MOR process. • Ni 2 P nanosheet with Cu 2 O-Cu dendrites on nickel foam was facilely synthesized. • Cu 2 O-Cu@Ni 2 P/NF was used as an efficient electrocatalyst for HER and MOR. • A low cell voltage of 1.40 V affords 10 mA cm −2 in methanol electrolysis. • In situ Raman spectra reveal that Cu 2 O-Cu promotes generation of β-NiOOH in MOR. 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 catalysts, coupled with the cathodic hydrogen evolution reaction, is still a challenge. Herein, we used a Ni 2 P nanosheet array with Cu 2 O-Cu dendrites on nickel foam (Cu 2 O-Cu@Ni 2 P/NF) as an efficient and stable electrocatalyst 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 Cu 2 O-Cu promotes the generation of the β-NiOOH active phase, and converts to Cu(II)O under the electrolysis conditions. Furthermore, the methanol electrolysis cell utilizing Cu 2 O-Cu@Ni 2 P/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 H 2 production.