Engineering Amorphous–Crystalline CoNi Interfaces via Substrate Modification for Enhanced Hydrogen Evolution

The interface between the amorphous and crystalline phases plays a crucial role in the electrocatalytic activity of transition metal-based electrocatalysts. In the quest for advanced catalysts for the electrocatalytic hydrogen evolution reaction (HER), this study introduces an a-Co/c-Ni@CP-600s catalyst synthesized through an electrodeposition approach, endowing it with both amorphous and crystalline properties. This generates highly active synergistic dual sites at the amorphous Co-crystalline Ni interface. The a-Co/c-Ni@CP catalyst exhibits excellent hydrogen evolution performance in an alkaline HER environment, with an overpotential of only 41 mV at a current density of 10 mA·cm–2. In terms of stability, the catalyst exhibits outstanding long-term stability, maintaining the initial overpotential for over 200 h under a constant current and demonstrating excellent performance as a cathode of an anion exchange membrane (AEM) electrolyzer. In situ Raman experiments and advanced first principles calculations indicate that the amorphous–crystalline CoNi interface significantly enhances the adsorption of H2O and the Gibbs free energy of the HER process. Specifically, Ni serves as the active site for water dissociation, while Co acts as the active site for H* adsorption and H2 evolution. This work successfully demonstrates the synthesis of a robust carbon-based CoNi catalyst with excellent electrocatalytic properties and highlights the significant impact of the Ni–Co interface on catalytic performance.