▎ 摘　　要

NOVELTY - A composite electrocatalyst comprises three-phase nickel sulfide inner layer sandwich frame structure sulfide outer layer doped graphene sandwich layer doped three-phase, and has rough surface. The composition of the three-phase nickel sulfide outer layer and the three-phase nickel sulfide inner layer comprises nickel sulfide compound. USE - Composite electrocatalyst used in electrocatalytic cracking of water to produce hydrogen (claimed). ADVANTAGE - The composite electrocatalyst can provide different types and rich active sites, regulate the interface electron transport, and promote the continuous and rapid occurrence of the multi-step reaction of electrocatalytic hydrogen evolution. The graphene in the middle layer of the sandwich frame structure can enhance the electron transmission rate, and improve the mechanical integrity of the composite structure, thereby improving its electrochemical performance and stability. DETAILED DESCRIPTION - A composite electrocatalyst comprises three-phase nickel sulfide inner layer sandwich frame structure sulfide outer layer doped graphene sandwich layer doped three-phase, and has rough surface. The composition of the three-phase nickel sulfide outer layer and the three-phase nickel sulfide inner layer comprises nickel sulfide compound of formula: NiS-NiS2-Ni3S4. INDEPENDENT CLAIMS are included for the following: (1) preparation of the composite electrocatalyst, which involves providing foam nickel doped graphene, using graphene as the shell layer and foam nickel as the core layer, mixing the foam nickel doped graphene with a sulfur source, ammonium halide and water, and performing a hydrothermal reaction; and (2) use of the composite electrocatalyst in electrocatalytic cracking of water to produce hydrogen.