A copper interface promotes the transformation of nickel hydroxide into high-valent nickel for an efficient oxygen evolution reaction

Abstract

The anodic oxygen evolution reaction (OER) hinders the development of hydrogen production by electrolysis of water due to its slow reaction kinetics. Nickel in its high-valent state has shown promising OER activity, which is, however, not preferred at relatively low overpotentials. To overcome this issue, we developed a sandwiched Ni(OH)₂/Cu/NF structure by coating a layer of Cu on the Ni foam and then depositing Ni(OH)₂ onto the Cu surface. Systematic characterization indicated that the Cu layer enhanced the conversion of Ni(OH)₂ into high-valence state Ni³⁺ species (i.e., NiOOH) during the OER, resulting in excellent OER performance with a current density of 50 mA cm⁻² for 25 hours at an overpotential of 250 mV. This work offers a promising approach to use Cu to promote the OER performance of Ni-based catalysts.