Photocatalytic fuel cell – A review

Photocatalytic oxidation has been widely investigated and applied to perform degradation of organic pollutants in water and air. In recent technological advancement, photocatalysis (PC) is integrated into fuel cell (FC) to form photocatalytic fuel cell (PFC) for simultaneous wastewater treatment and production of electricity. In the PFC mechanisms, the organic pollutant, acting as a fuel in the fuel cell component, is decomposed upon light activation at the photoanode and the flow of photoexcited electrons is driven by the potential difference between the two electrodes. Thus, unwanted electron-hole recombination is effectively inhibited, resulting in enhanced PC activity. In other words, the chemical energy stored in the organic pollutant is recovered and converted into useful electricity during the wastewater treatment process. The photoelectrochemical technology can also be implemented for hydrogen generation and carbon dioxide reduction. Various strategies have been investigated for improving the PFC mechanisms through better visible-light photoelectrodes, innovative cell designs, dual-photoelectrode setup, as well as optimal control. In this review, the fundamentals and technological development of PFC will be discussed with special attention to novel cell configurations. With better knowledge and understanding of the PFC, we can identify promising research directions to further develop the PFC technologies.