Singlet oxygen-selective cleavage pathway for concurrent maximized mineralization and electricity production from flotation wastewater enabled by oxygen vacancy-enriched B/P co-doped BiPO4/Bi2MoO6 photoanode

The photocatalytic fuel cell (PFC) can treat the increasingly severe pollution from flotation wastewater in the mining industry by simultaneously converting the chemical energy of pollutants into electricity. The inherent thermodynamic and kinetic differences in degradation pathways are crucial for governing pollutant mineralization and electricity generation in the PFC system. However, achieving simultaneous contaminant elimination and maximum energy recovery through rational pathway modulation remains challenging. Herein, oxygen vacancy-enriched heterostructured BiPO 4 /Bi 2 MoO 6 photoanode by B/P co-doping, denoted as BPO/BP-BMO, is constructed via a one-step acid-mediated solvothermal method. The in-situ heterojunction and oxygen vacancies induced by heteroatom doping effectively modulate electronic/band structures, optimize interfacial charge transfer, and enhance electron-hole pair separation efficiency. The optimal BPO/BP-BMO photoanode exhibits enhanced production of singlet oxygen ( 1 O 2 ) under visible-light irradiation, which is critical for regulating the degradation pathways of sodium isopropyl xanthate (SIPX). Experimental and theoretical studies have shown that 1 O 2 preferentially targets the -O-CSS- bond in SIPX, leading to the rapid formation of isopropanol, a compound that mineralizes quickly, while minimizing the buildup of unreactive intermediates such as ROCS₂O − . The isopropanol-oriented degradation pathway endows the BPO/BP-BMO-PFC system with 92 % degradation efficiency within 90 min and a power density of 9.7 μW cm −2 , with the latter being 1.8 times that of the Bi 2 MoO 6 -PFC system. This study demonstrates an advanced photoanode, progressing from rational defect/heterojunction design to degradation pathways regulation, thereby establishing a more effective PFC system for sustainable wastewater-to-energy conversion processes.