High‐Entropy Alloy/Intermetallic Compound Heterostructures for Efficient Hydrazine Oxidation‐Assisted Hydrogen Production

Configuring integrative catalytic heterostructures is an efficient strategy to circumvent the universal linear scaling relationships for accelerating multiple-intermediate redox reactions. Here this study reports nonprecious metal-based high-entropy alloy/intermetallic compound heterostructure with a 3D nanoporous architecture as a high-performance electrocatalyst for hydrazine oxidation reaction. By making use of strain engineering of hexagonal close-packed multicomponent intermetallic compound core, high-entropy NiFeCoCuCrMn alloy surface is comprised of multiple active centers with undulatory adsorption energies, which enable *N₂H_x intermediate spillover to adjust rate-determining step and lower kinetic barriers. As a consequence of nanoporous architecture endowing abundant multiple active surfaces, this heterostructure mediates hydrazine electrooxidation of as high as ampere-level current densities at >0.08 V versus reversible hydrogen electrode, showing genuine potential to replace sluggish oxygen evolution reaction for hydrogen production via water electrolysis. Its hydrazine oxidation-assisted water electrolyser delivers 500 mA cm^-2 at ultralow cell voltage of 0.87 V, and maintains exceptional stability for 1000 h.