Activating multisite high-entropy alloy nanocrystals via enriching M–pyridinic N–C bonds for superior electrocatalytic hydrogen evolution

The activation of multisite high-entropy alloy (HEA) electrocatalysts is helpful for improving the atomic utilization of each metal in water electrolysis catalysis. Herein, well-dispersed HEA nanocrystals on N-rich graphene with abundant M-pyridinic N-C bonds were synthesized through an ultrasonic-assisted confinement synthesis method. Operando Raman analysis and density functional theory calculations revealed that the electrocatalysts presented the optimal electronic rearrangement with fast rate-determined H2O dissociation kinetics and favorable H* adsorption behavior that greatly enhanced hydrogen generation in alkaline electrolyte. A small overpotential of only 138.6 mV was required to obtain the current density of 100 mA cm-2 and the Tafel slope of as low as 33.0 mV dec-1, which was considerably smaller than the overpotentials of the counterpart with poor M-pyridinic N-C bonds (290.4 mV) and commercial Pt/C electrocatalysts (168.6 mV). The atomic structure, coordination environment, and electronic structure were clarified. This work provides a new avenue toward activating HEA as advanced electrocatalysts and promotes the research on HEA for energy-related electrolysis.