NOVELTY - Usage method of single chamber fuel cell involves using a single-chamber fuel cell as a reactor, an air electrode with platinum carbon as catalyst as a cathode, and a carbon material as an anode. The anode is inserted into electrolyte solution in the reactor and connected with the cathode outside the reactor through a wire, and a cation exchange membrane is arranged between the reactor and the cathode. Buffering agent, complexant and iron (III) compound are added when the fuel cell is in an open circuit state, nitrogen is provided and oxygen is removed.    USE - Usage method of single chamber fuel cell (claimed).    ADVANTAGE - The method efficiently uses single chamber fuel cell with high coulombic efficiency.    DETAILED DESCRIPTION - Usage method of single chamber fuel cell involves using a single-chamber fuel cell as a reactor, an air electrode with platinum carbon as catalyst as a cathode, and a carbon material as an anode. The anode is inserted into electrolyte solution in the reactor and connected with the cathode outside the reactor through a wire, and a cation exchange membrane is arranged between the reactor and the cathode. Buffering agent, complexant and iron (III) compound are added when the fuel cell is in an open circuit state, pH value of electrolyte solution is adjusted to 5-9, nitrogen is provided and oxygen is removed. A sulfide is added into the electrolyte solution, and reacted in the closed reactor for 7-9 hours at room temperature. An electrolyte solution is added with chloroform extracting, elemental sulfur and iron (II) are reclaimed in the circuit, and electrolyte solution in ionizated to generate iron (III) ion. The electrolyte solution is sodium chloride solution. The concentration of electrolyte solution is 10-100 mmol. The buffering agent is chosen from carbonic acid and bicarbonate. The complexing agent is chosen from ethylene diamine tetraacetic acid salt, citrate or nitrilotriacetic triacetate. The sulfide is ionized to generate sulfur ion in the electrolyte solution. The addition amount of sulfide is 1-5 mmol.