Hydrogen peroxide photo-fuel cells

Hydrogen peroxide (H2O2) possesses both strong oxidizing and moderate reducing ability. Due to the unique chemical reactivity, one-compartmentalization of fuel cells is possible by using H2O2 as both the fuel and oxidant for fuel cells (H2O2-FC). To enhance the anode reaction (H2O2 -> O2 + 2H+ + 2e-) of the H2O2-FC, a noble metal-free H2O2-photo fuel cell (PFC) has been newly developed for enhancing the conversion from chemical energy to electric energy with only emission of water and oxygen. The H2O2-photo fuel cells (PFC) take several significant advantages over the conventional hydrogen-oxygen fuel cells. With the realization of a solar-driven energy cycle with H2O2 as the key substance in mind, this Frontier article highlights the H2O2-PFCs. Firstly, the fundamentals of the H2O2-PFC are dealt with by treating the prototype using TiO2 as the photoanode. Then, recent progress in the H2O2-PFCs and an emerging application to self-powered biosensors are described. Finally, the conclusions are summarized with the future outlook. H2O2-photofuel cell (PFC) is an important photoelectrochemical device contributing to the realization of a solar-driven clean energy cycle named the "hydrogen peroxide-keyed energy cycle" through combination with the photocatalytic H2O2 synthesis.