Enhanced performance and stability of sulfite/sulfide-assisted photocatalytic fuel cell with CdS@TNTs/Ti mesh photoanode

In this work, a Z-scheme heterojunction CdS@TNTs/Ti mesh photoanode is developed and incorporated into a photocatalytic fuel cell (PFC) with the addition of sulfite/sulfide, forming a sulfite/sulfide-assisted PFC with the CdS@TNTs/Ti mesh photoanode. Such a photoanode enhances not only the light absorption range but also the charge separation with maintaining redox potentials. The addition of sulfite/sulfide greatly improves the photoanode stability and the solution conductivity. More importantly, strong synergistic effect between the activation of sulfite/sulfide and Z-scheme heterojunction having a high intrinsic activity allows for more reactive radicals to be generated, spreads the reaction region from the photoanode interface to the entire system and suppresses the charge recombination. Thus, the CdS@TNTs/Ti mesh photoanode exhibits superior photocatalytic/photoelectrochemical performances in the presence of sulfite/sulfide. The sulfite/sulfide-assisted PFC with the Z-scheme heterojunction CdS@TNTs/Ti mesh photoanode yields the degradation efficiency, maximal power density and short current density as high as 80.25 %, 0.90 mW/cm², and 2.58 mA/cm², respectively, substantially exceeding the PFC without sulfite/sulfide. This work not only enhances the comprehension of the synergistic enhancement mechanism by inducing sulfite/sulfide, but also provides a promising and green choice for the development of the PFC system to efficiently remove pollutants in sewage and generate electricity concurrently.