Tungstate-modulated Ni/Ni(OH)2 interface for efficient hydrogen evolution reaction in neutral media

Abstract

Developing highly efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) in neutral media is crucial but still a significant challenge on account of the sluggish multistep reaction kinetics involved. Theoretically, constructing a metal/metal hydroxide interface with a metal hydroxide acting as a water dissociation promotor and a metal as the subsequent hydrogen adsorption site is expected to accelerate the HER kinetics in neutral media. We found that the intercalation of tungstate into Ni(OH)₂ can tune the electronic structure of the Ni/Ni(OH)₂ interface, decrease the energetic barrier for the Volmer step, and thus optimize the HER performance of Ni/Ni(OH)₂ hybrid. Herein, a heterostructured Ni/Ni(OH)₂ nanosheet array on Cu foam is designed and constructed via a simple hydrothermal and subsequent plasma reduction strategy. The HER performance can be further enhanced by assembling tungstate-intercalated Ni/Ni(OH)₂ hybrid nanosheets on Cu₂O nanotube arrays, exhibiting a low overpotential (39 mV @ 10 mA cm⁻²) and excellent stability (48 h).