▎ 摘　　要

NOVELTY - Electrode catalyst comprises a first transition metal foam, a metal double hydroxide (LDH)/metal oxide mixed layer comprising a second transition metal and a third transition metal formed on the surface of the first transition metal foam, and fourth transition metal oxyhydroxide nanoparticles formed on the surface of the mixed layer. the mixed layer surface comprises the metal double layer hydroxide. USE - The catalyst is useful for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline seawater (claimed). ADVANTAGE - The catalyst has high stability that can sustain seawater splitting efficiently without chloride corrosion, high durability, and efficiency without chloride corrosion and voltage increase. produces high current density even at low overvoltage, achieves high level of oxygen production, produces high current density even at low overvoltage, improves electrical conductivity and contributes to OER activity, exhibits excellent HER activity in alkaline seawater, and effectively improves the active surface area. The method is simple, economical, and suitable for mass production. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for producing electrode catalyst, comprising (a) forming metal double-layer hydroxide containing second transition metal and third transition metal on the surface of the first transition metal foam by immersing first transition metal foam (roam) in a solution containing second transition metal and third transition metal (layered double hydroxide), (b) annealing the metal double layer hydroxide to form metal double layer hydroxide/metal oxide mixed layer, and (c) immersing in solution containing fourth transition metal oxyhydroxide precursor to form fourth transition metal oxyhydroxide nanoparticles on the surface of the mixed layer; and #seawater decomposition system, comprising electrode catalyst.