Interfacial electron transfer of a MOF-derived Co–B–P catalyst for the hydrogen evolution reaction with improved activity and stability

Abstract

Transition metal borides (TMBs) are a vital category of electrocatalytic materials for water splitting. Phosphorus incorporation is a common strategy for enhancing catalytic activity of TMBs, with Co–B–P systems receiving particular attention. However, most Co–B–P systems exhibit an amorphous structure, which hinders mechanistic understanding and impedes further improvement of their electrocatalytic performance. In this study, we successfully synthesized a well-defined CoB/Co₂P hierarchical nanoarray (CoB/Co₂P HNA) electrocatalyst. And the use of a MOF-derived precursor results in a hierarchical nanoarray architecture with a large specific surface area and abundant exposed active sites. CoB/Co₂P HNA exhibits excellent performance for the alkaline hydrogen evolution reaction with a low overpotential of 109 mV to achieve 10 mA cm⁻², and retains 90% of its activity after 65 hours of stability testing. Theoretical calculations reveal the interfacial charge enrichment toward Co sites at the CoB/Co₂P interface, which enhances the catalytic activity and stability of the system.