Multicomponent Intermetallic Nanoparticles on Hierarchical Metal Network as Versatile Electrocatalysts for Highly Efficient Water Splitting

Abstract Developing high‐efficiency and cost‐effective alloy catalysts toward hydrogen‐evolution reaction (HER) is crucial for large‐scale hydrogen production via electrochemical water splitting, but conventional single‐principal‐element alloy design usually causes insufficient activity and durability of state‐of‐the‐art multimetallic catalysts based on non‐precious transition metals. Herein, we report multicomponent intermetallic Mo(NiFeCo) 4 nanoparticles seamlessly integrated on hierarchical nickel network (Mo(NiFeCo) 4 /Ni) as robust hydrogen‐evolution electrocatalysts with remarkably improved activity and durability by making use of iron and cobalt atoms partially substituting nickel sites to form high‐entropy NiFeCo sublattice in intermetallic MoNi 4 matrix, which serve as bifunctional electroactive sites for both water dissociation and adsorption/combination of hydrogen intermediate and improves thermodynamic stability. By virtue of bicontinuous nanoporous nickel skeleton facilitating electron/ion transportation, self‐supported nanoporous Mo(NiFeCo) 4 /Ni electrode exhibits exceptional HER electrocatalysis, with low Tafel slope (≈35 mV dec −1 ), high current density (≈2300 mA cm −2 ) at low overpotential (200 mV) and long‐term durability in 1 m KOH. When coupled to its electrooxidized and nitrified derivative for oxygen‐evolution reaction, their alkaline water electrolyzers operate with a superior overall water‐splitting output, outperforming the one constructed with commercially available noble‐metal‐based catalysts. These electrochemical properties make it an attractive candidate as electrocatalyst in alkaline water electrolysis for large‐scale hydrogen generation.