Construction of solar-driven electron transfer chain based on FeCl3/TiO2 synergetic mediators for highly efficient conversion of lignin into electricity

Biomass flow fuel cells (BFFCs) are effective energy conversion technologies for converting biomass into electricity to realize a sustainable society. However, most of them depend on the thermal degradation of biomass, which is energy consumption and induces biomass polycondensation. Herein, we develop a novel solar-driven BFFC for converting lignin into electricity under sunlight at room temperature based on FeCl 3 /TiO 2 synergetic mediators, which endow a broad photo-absorption range and enhance absorption intensity for high photocatalytic activity. A new electron transfer chain is constructed by employing Fe 3+ to obtain electrons and efficiently promote electron-hole separation of TiO 2 . Meantime, the generated ·OH can depolymerize lignin rapidly. The BFFC achieved a power density of 64.4 mW/cm 2 at room temperature via sunlight irradiation with sodium lignosulfonate as fuel when paired with VO 2 + /VO 2+ catholyte. It can stably discharge and power LED light successfully. This work provides a sustainable and energy conservation approach for developing advanced biomass fuel cells.