Gas diffusion TiO photoanode for photocatalytic fuel cell towards simultaneous VOCs degradation and electricity generation.

In this work, a photocatalytic fuel cell (PFC) with a gas diffusion TiO photoanode is proposed to directly convert chemical energy contained in volatile organic compounds into electricity by using solar energy. The gas diffusion TiO photoanode is prepared by coating TiO nanoparticles onto Ti mesh, whose intrinsic porous structure allows for gaseous pollutants to directly transfer inside the photoanode and thereby enhances mass transport. The feasibility of the developed gas diffusion photoanode is demonstrated by degrading toluene as a model gaseous pollutant. It is shown that the newly-developed PFC yields better electricity generation and toluene removal efficiency due to the enhanced mass transport of toluene and the eliminated interference of gas bubbles. The short-circuit current density and maximum power density of the PFC with a gas diffusion TiO photoanode (0.1 mA/cm and 0.02 mW/cm) are about 3.3 times and 4 times as those of the bubbling PFC (0.03 mA/cm and 0.005 mW/cm), respectively. Both the discharging performance and toluene removal efficiency increase with increasing the light intensity and electrolyte concentration, while there exists an optimal gas flow rate leading to the best performance. The present work provides an innovative strategy for clean processing of volatile organic compounds while recycling the contained chemical energy.