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 HO 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 and the Tafel slope of as low as 33.0 mV dec, 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.