Multi-phase and multi-species transport inside air-breathing photocathode of photocatalytic fuel cell

Abstract

A deep understanding of the two-phase and multispecies transport coupled with photoelectrochemical oxygen reduction reaction is crucial for boosting a photocatalytic fuel cell with a photoanode and an airbreathing photocathode. Herein, a pore network model is developed for the air-breathing CuO photocathode employed in photocatalytic fuel cell to describe the twophase percolation and multi-species transport as well as their effect on the photocathode performance. The performance of the air-breathing photocathode is found to be greatly affected by the wettability-dependent liquid invasion into the gas diffusion layer. Increasing the proportion of hydrophilic pores/throats in the gas diffusion layer greatly lowers the photocathode performance because of more severe liquid invasion. Besides, the transport of active species, including the dissolved oxygen and photo-excited electron and hole, has a significant effect on the photocathode performance. The present work also provides a guidance for the optimal design of the air-breathing photocathode.