3D ordered macroporous copper nitride–titanium oxynitride as highly efficient electrocatalysts for universal-pH hydrogen evolution reaction

Abstract

The demand for hydrogen for future clean energy has increased research interest in developing non-noble high-efficiency electrocatalysts for the hydrogen evolution reaction (HER). In this study, we prepared a copper nitride-loaded 3D ordered macroporous titanium oxynitride (Cu₃N@3DOM-TiO_xN_y) via PS-metal sol–gel and ammonia annealing method. The present Cu₃N@3DOM-TiO_xN_y as an electrocatalyst demonstrated high efficiency towards the HER, with low overpotentials ranging from 71 to 79 mV at a current density of 10 mA cm⁻² in all-pH electrolyte. Additionally, the low Tafel slopes of the Cu₃N@3DOM-TiO_xN_y revealed the fast electron transfer in the electrocatalytic process. In-depth investigation illustrated that the Cu₃N with an extremely low activation barrier energy associated with rapid H₂ release process works as the main active site and plays a pivotal role in efficiently electrocatalysing the HER. This work not only proposes a highly efficient, robust and low-cost copper-based all-pH HER electrocatalyst, but also demonstrates the significance of nano-engineering in developing next-generation electrocatalysts.