Photocatalytic fuel cell based on dual Z-scheme heterojunction photoanode InVO4/g-C3N4/Bi2WO6/Ti for efficient Rhodamine B degradation and power generation

•The double Z-scheme heterojunction InVO4/g-C3N4/Bi2WO6/Ti photoanode was prepared.•The photoanode has efficient separation of carriers and strong redox capability.•The RhB degradation rate, Jsc and Pmax of this PFC were 93.1 %, 0.223 mA cm−2 and 18.02 µW cm−2, respectively.•RhB was degraded by O2−, h+ and OH through deethylation and ring-opening reactions. Finding suitable semiconductor materials to construct efficient photoanode is the key to improve PFC performance. In this paper, InVO4/g-C3N4/Bi2WO6/Ti composite photoanode was prepared and assembled with Cu cathode to construct PFC for rhodamine B (RhB) degradation and power generation. The InVO4/g-C3N4/Bi2WO6/Ti photoanode was characterized by XRD, FT-IR, XPS, SEM, TEM, EDS and DRS. The electrochemical properties of the PFC including polarization curves, power density, transient photocurrent, LSV and CV curves were analyzed to explore its power generation and electron transfer mechanism. The results showed that the ternary composite photoanode had stronger light absorption, smaller Eg (1.96 eV) and Rct (0.71 Ω), and higher photocurrent current density (0.16 mA cm−2) than binary and single composite photoanodes, indicating that it had higher utilization rate of excitation light energy and carrier mobility. The RhB degradation rate, Pmax, Jsc and Voc of PFC were 93.1 % (90 min), 18.02 µW cm−2, 0.223 mA cm−2 and 0.44 V, respectively. Further mechanistic studies show that the PFC has good photoexcited carrier separation and strong redox capacity due to double Z-scheme heterojunction between Bi2WO6 and InVO4 and between Bi2WO6 and g-C3N4, so as to generate more O2− and h+ to degrade RhB through N-deethylation, dealkylation and ring opening reactions. This study provides a practical approach for the development of high-efficiency double Z-scheme composite photoanode.