▎ 摘　　要

NOVELTY - Cocatalyst is cobaltphosphorus or cobaltphosphorus-graphene composite. USE - Cocatalyst for photocatalytic decomposition of formic acid in photocatalytic system. ADVANTAGE - The cocatalyst has selective electrode is cost effective, does not need complicated reaction apparatus. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a photocatalytic system, which comprises cocatalyst, junction formed by a semiconductor and a promoter, formic acid, and water, where semiconductor is cadmium sulfide nano particle; and (2) mixing knot, formic acid and water to mixed reaction liquid, irradiating mixed reaction liquid with light source to generate Hydrogen and carbon dioxide.