▎ 摘　　要

NOVELTY - Water decomposition catalyst comprises metal compound having perovskite structure, and mixed with metal compound, and metal-intercalated transition metal chalcogenide (TMD). The metal compound and metal-inserted transition metal chalcogen compound is to form heterogeneous structure. USE - The water decomposition catalyst is useful in water splitting device. ADVANTAGE - The water decomposition catalyst: has good oxidation resistance; has excellent water decomposition performance comparable to noble metal water decomposition catalysts and securing economic efficiency and excellent stability; has excellent water decomposition performance comparable to a noble metal water decomposition catalyst; realize commercialization of an energy converter and has improved long-lasting stability; has excellent driving stability. The method is economical and suitable for mass-production; replaces a noble metal-based catalyst and has scalability of materials and perspective for maximizes performance of heterogeneous water electrolysis catalysts. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) producing a water decomposition catalyst comprising inserting metal into transition metal chalcogen compound by intercalation method to synthesize metal-inserted transition metal chalcogen compound, preparing synthesized metal-inserted transition metal chalcogen compound as powder, preparing metal compound powder having perovskite structure, preparing dispersion solution by dispersing metal-inserted transition metal chalcogen compound powder, where the metal compound powder and carbon material in organic solvent, and obtaining water decomposition catalyst powder by synthesizing dispersion solution through wet ball mill method and then drying; and (2) water decomposition device comprising water decomposition catalyst of oxide electrode, and reduction electrode