Achieving advanced hydrogen evolution under large current density by amorphous/crystalline core-shell electrocatalyst of a-NiCoP/Co2P

Non-precious transition metal-based electrocatalysts with high activity are the promising candidates for substituting Pt- or Ru-based electrocatalyst in hydrogen evolution. In this study, we proposed a core-shell engineering to combine the amorphous NiCoP and crystalline Co2P (a-NiCoP/Co2P@NF), which requires an ultra-low overpotential of only 26 mV to achieve the benchmark current density of 10 mA cm-2. Furthermore, it achieves an industrial-level hydrogen evolution current density of 500 mA cm-2 with excellent stability. The superior catalytic performance and stability can be attributed to the hierarchical amorphous/crystalline interface and the electron-rich interfacial Co sites. Amorphous NiCoP shell can not only protect the internal Co2P from corrosion, but also provide a larger electrochemical active area. Together, the Co2P core provides fast electron transport and promotes H2 emission from the interfacial electron-rich Co sites. This work gives inspiration to the rational design of advanced core-shell structure between amorphous and crystalline.