Wangman Yin,Xinman Tu,Xinding Lv,Li Zhang,Tingting Li,Xiaojun Wang,Jianping Zou
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.
Yuqing Luo,Binbin Pan,Xiaohan Yu,Xue Ding,Xinmin Shi,Yanguang Li
The electrochemical reduction of CO 2 to formic acid or formate represents one of the most economically promising route for CO 2 utilization. While substantial advances in catalyst design and electrolyzer engineering have been achieved in recent years, critical uncertainties remain regarding the reaction pathway and the often-debated role of alkali metal cations. Resolving these discrepancies requires precise kinetic analysis under well-defined conditions. In this work, we systematically investigate the kinetics of CO 2 reduction to formic acid or formate across a wide pH range, enabled by two key developments: the identification of BiPO 4 as a stable precatalyst under acidic conditions through comprehensive screening, and the implementation of sensitive ion chromatography for accurate product quantification, even at low current density where conventional methods struggle. Our electrokinetic data suggest that the reaction proceeds via sequential electron and proton transfers rather than proton-coupled electron transfer as proposed by many computational simulations. Notably, the rate-determining step transitions from the proton transfer step at low overpotential to the first electron transfer step at high overpotential, with the proton source dependent on electrolyte pH. Furthermore, through K + reaction order analysis and crown ether chelation experiments, we demonstrate that the alkali cations are not merely spectators but actively participate in the reaction, likely by stabilizing negatively charged intermediates via electrostatic interactions.
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