Visible-light responsive photocatalytic fuel cell with double Z-scheme heterojunction PTh/Ag3PO4/BiOI/Ti photoanode for efficient rhodamine B degradation and stable electricity generation

The development of photocatalytic fuel cell (PFC) with visible-light response is usually limited by the low efficiency of electron-hole separation in photoanode . In this work, 20%-PTh/Ag 3 PO 4 /BiOI/Ti photoanode was prepared for the first time to construct a PFC with Cu 2 O/Cu cathode to degrade rhodamine B. With visible-light stimulation, the rhodamine B degradation rate, maximum photocurrent density and maximum power density of the PFC were respectively 96.33% (2 h), 0.39 mA cm −2 and 82.20 μW cm −2 . The main active species in the PFC were proved by quenching experiments to be h + , ∙OH and ∙O − 2 . The satisfactory performance of the PFC was due to that a double Z-scheme heterojunction was formed in the photocatalyst of 20%-PTh/Ag 3 PO 4 /BiOI/Ti photoanode, which made the photogenerated electrons of Ag 3 PO 4 and BiOI directly combine with the photogenerated holes of PTh , so that the photogenerated holes of Ag 3 PO 4 and BiOI and the photogenerated electrons of PTh directly or indirectly participated in the degradation reaction of RhB. In this way, the separation efficiency of electron-hole pairs in the photoanode was improved, and the performance of the PFC was significantly enhanced.