The anode loses electrons to generate carbon dioxide gas, and sodium carbonate is added, which reacts with carbon dioxide to generate sodium bicarbonate, and the cathode CO gains electrons to generate methane gas. Accordingly, the ion reaction equation is 4co+3co+5h2o = = 6h co+CH4, and the cathode electrode reaction equation is co+6e-+5h2o = = 6oh-+CH4.
A method for preparing methane by reduction of carbon dioxide comprises the following steps: arranging a cathode battery, an anode battery, a diaphragm, a cathode electrode and an anode electrode in the form of primary batteries.