In Situ Formed Carbon‐Encapsulated RuNi Alloy and Ni Heterointerface as an Efficient HER Electrocatalyst for Alkaline Water Splitting

Abstract Ru‐based catalysts have emerged as promising candidates due to their high catalytic activity, yet issues such as kinetic sluggishness and insufficient stability remain. In this study, a carbon‐encapsulated RuNi/Ni heterostructured nanoparticle on coal‐based carbon nanofiber (RuNi/Ni@C‐CNF) is constructed through an in situ pyrolysis strategy. The strategy achieves the highly dispersed loading of metal nanoparticles while synchronously enabling the catalytic graphitization of carbon nanofibers via precursor impregnation coupled with in situ carbothermal reduction. RuNi/Ni@C‐CNF exhibits excellent HER activity in 1 m KOH electrolyte. The overpotential is 9 mV at 10 mA cm −2 , and it demonstrates remarkable stability over 300 h. Meanwhile, RuNi/Ni@C‐CNF serves as both the anode and cathode in an assembled electrolyzer, the system requires only 1.49 V cell voltage to achieve 10 mA cm −2 . The RuNi alloy regulates the D‐band center of the Ni sites through the electron transfer effect, reducing the energy barrier for water dissociation. Meanwhile, the RuNi/Ni interface synergistically optimizes the free energy of hydrogen adsorption. In addition, the encapsulated carbon effectively confines the metal particles aggregation, and protects the metal active sites from (electro)chemical corrosion by alkaline electrolyte. This work provides a new idea for design of carbon‐encapsulated heterostructured alkaline HER catalysts.