Sustainable dual-cathode photoelectro-Fenton-like system at a wide pH range for rapid degradation of emerging pollutants

In-situ Fenton like process was highly promising and energy-efficient for treating emerging organic contaminants. However, the challenge in the production and activation of H₂O₂ faces its practical application. Herein, a photoelectro-Fenton-like (PEF) system was successfully fabricated with BiVO₄ thin-film, graphite (C) and PhC₂Cu as photoanode, cathode and photocathode, respectively. The ternary system was applied for visible-light degradation of Tetracycline (TC) at a low potential of 0.5 V·H₂O₂ was generated at the graphite cathode and then activated to produce •OH by Cu(Ⅰ) from PhC₂Cu photocathode. The photo-generated electrons accelerated the Cu(Ⅰ)/Cu(Ⅱ) cycle to achieve sustainable PEF reactions. After 150 min of illumination, 97 % TC was degraded in BiVO₄|C|PCu system, superior to BiVO₄|C and BiVO₄|PCu systems. The outstanding stability and reusability of this PEF system was proved by 10 cycles. Moreover, the vulnerable atomic sites of TC molecule were predicated by the Fukui function. Both inhibition zone tests of bacteria and wheat seeds cultivation experiments proved that the constructed PEF system displayed outstanding performance in hampering TC eco-toxicity. For example, the Fv/Fm fluorescence image map demonstrated that the constructed PEF system not only degraded organic pollutants but also lowered their toxicity. Finally, the mechanism of in-situ generation and activation of H₂O₂ was proposed based on the results of quenching experiments, PL spectra and ESR technique. Overall, this study provides a promising pathway to remediate environmental pollution through constructing a PEF system based on dual cathodes.