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

Abstract

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/Ag3PO4/BiOI/Ti photoanode was prepared for the first time to construct a PFC with Cu2O/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/Ag3PO4/BiOI/Ti photoanode, which made the photogenerated electrons of Ag3PO4 and BiOI directly combine with the photogenerated holes of PTh, so that the photogenerated holes of Ag3PO4 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.