A solar storable fuel cell with efficient photo-degradation of organic waste for direct electricity generation

Solar fuels and fuel cells are two of the key enabling technologies for clean and sustainable electricity generation. However, photo-synthesis of hydrocarbon or hydrogen fuels is kinetically slow and low efficient, while the current fuel cells use pure hydrogen fuel and precious metal electro-catalysts, which pose severe cost and resource restraints for commercial application. Here, we propose and construct a solar storable fuel cell (SSFC) based on the photo-oxidation of organic wastes and the oxygen reduction reaction at the MnO2 air cathode, which generates electricity with simultaneous photo-degradation of organic contaminants in waste water. As a proof-of-principle device, the SSFC delivers a stable voltage of +0.6 V at constant current of 20 μA cm−2 with almost complete degradation of methyl orange in aqueous solution in an hour, demonstrating an effective utilization of the organic waste for direct electricity generation.