Interfacial engineering of Co5.47N/Mo5N6 nanosheets with rich active sites synergistically accelerates water dissociation kinetics for Pt-like hydrogen evolution

The development of highly efficient hydrogen evolution electrocatalysts with platinum-like activity requires precise control of active sites through interface engineering strategies. In this study, a heterostructured Co5.47N/Mo5N6 catalyst (CoMoNx) on carbon cloth (CC) was synthesized using a combination of dip-etching and vapor nitridation methods. The rough nanosheet surface of the catalyst with uniformly distributed elements exposes a large active surface area and provides abundant interface sites that serve as additional active sites. The CoMoNx was found to exhibit exceptional hydrogen evolution reaction (HER) activity with a low overpotential of 44 mV at 10 mA cm-2 and exceptional stability of 100 h in 1.0 M KOH. The CoMoNx(-)||RuO2(+) system requires only 1.81 V cell voltage to reach a current density of 200 mA cm-2, surpassing the majority of previously reported electrolyzers. Density functional theory (DFT) calculations reveal that the strong synergy between Co5.47N and Mo5N6 at the interface can significantly reduce the water dissociation energy barrier, thereby improving the kinetics of hydrogen evolution. Furthermore, the rough nanosheet architecture of the CoMoNx catalyst with abundant interstitial spaces and multi-channels enhances charge transport and reaction intermediate transportation, synergistically improving the performance of the HER for water splitting.