Hydrogen peroxide photo-fuel cells.

Hydrogen peroxide (H 2 O 2 ) possesses both strong oxidizing and moderate reducing ability. Due to the unique chemical reactivity, one-compartmentalization of fuel cells is possible by using H 2 O 2 as both the fuel and oxidant for fuel cells (H 2 O 2 -FC). To enhance the anode reaction (H 2 O 2 → O 2 + 2H + + 2e - ) of the H 2 O 2 -FC, a noble metal-free H 2 O 2 -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 H 2 O 2 -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 H 2 O 2 as the key substance in mind, this Frontier article highlights the H 2 O 2 -PFCs. Firstly, the fundamentals of the H 2 O 2 -PFC are dealt with by treating the prototype using TiO 2 as the photoanode. Then, recent progress in the H 2 O 2 -PFCs and an emerging application to self-powered biosensors are described. Finally, the conclusions are summarized with the future outlook.