▎ 摘　　要

NOVELTY - Preparing carbon nitride heterojunction photocatalyst involves dissolving graphene oxide in distilled water, sonicating, and then adjusting the pH to 9-11 to obtain a graphene oxide solution, adding metal oxide to the graphene oxide solution, and ultrasonicating for 2-4 hours to obtain a graphene oxide solution containing the metal oxide. A certain amount of carbon nitride is added to the graphene oxide solution containing metal oxides, and stirred for 12-16h. The mixture is reacted in a reactor at a certain temperature, and then freeze-dried to obtain a carbon nitride heterojunction catalyst. USE - Method for preparing carbon nitride heterojunction photocatalyst for preparing photocatalytic electrodes for reducing carbon dioxide to produce acetic acid in a microbial electrosynthesis system (all claimed). ADVANTAGE - The method enables to prepare carbon nitride heterojunction photocatalyst, which improves the acetic acid production efficiency of the bioelectrosynthesis system to reduce carbon dioxide. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for use of carbon nitride heterojunction photocatalyst is claimed for preparing photocatalytic electrodes, where carbon nitride heterojunction catalyst is dissolved in a solvent to prepare a catalyst solution, pretreated electrode is immersed in the catalyst solution, stirred for 6-10 h, then taken out, and dried to obtain a photocatalytic electrode.