▎ 摘　　要

NOVELTY - Photocatalytic reactor comprises a transparent columnar insulating shell (1), a graphene/silicon composite film (2) horizontally arranged in the columnar insulating shell, and an electrode plate mounted on the top surface and bottom surface of the columnar insulating casing, where the two electrode plates are respectively connected to the positive electrode and negative electrode of the power source. The side wall of the columnar insulating casing is provided with a gas injection hole (5), and the gas injection hole is sealed by an insulating rubber stopper. The graphene/silicon composite film comprises a graphene film and a silicon nano film on the front side of the graphene film, and the silicon nano film is composed of silicon nanoparticles. The graphene film layer is cross-linked, the graphene film has a thickness of 10-100 nm, and a defect density ID/IG less than or equal to 0.01. USE - Photocatalytic reactor. ADVANTAGE - The photocatalytic reactor catalyzes the formation of methane, carbon monoxide and oxygen by carbon dioxide and water. DETAILED DESCRIPTION - The graphene/silicon composite film is parallel to the upper and lower electrode plates, and the silicon nanolayer is on the low potential side. An INDEPENDENT CLAIM is included for a method for catalytically reducing carbon dioxide in a photocatalytic reactor, which involves: (A) injecting water vapor and carbon dioxide into the reactor through a gas injection hole, and then sealing; (B) connecting the two electrode plates to the positive and negative electrodes of the power supply, and illuminating the graphene surface; (C) seperating electrons and holes by the upper and lower electrode plates, and locating the separated electrons and holes on two surfaces of the composite film, where one side of the silicon nanoparticles is coated with electrons to form an electron layer, and the other side is formed with holes to form a hole layer; and (D) forming a potential difference between the electron layer and hole layer to reduce carbon dioxide and water to form methane, carbon monoxide and oxygen. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of photocatalytic reactor. Transparent columnar insulating shell (1) Graphene/silicon composite film (2) Anode plate (3) Cathode plate (4) Gas injection hole (5)