Binary regulation of photoelectron-heterojunction Sg-CN/BMO using sulfur-doping and oxygen vacancy construction for boosting chloroquine degradation

Photoelectrocatalysis (PEC) is a promising method for contaminant treatment, the preparation of photoelectrocatalyst is momentous for realization of superior PEC degradation efficiency. Herein, sulfur-doping g-CN and oxygen vacancy regulated bismuth molybdate heterojunction Sg-CN1/BMO5 was synthesized for chloroquine phosphate (CQ) degradation. Benefiting from band gap re-building and enhanced electronic transmission, the heterojunction displayed outstanding photoelectrocatalytic ability, and 90.2% of CQ can be degraded within 120 min. The degradation activity of Sg-CN1/BMO5 has been testified by pseudo-first-order rate constant, which was 3.03 and 2.66 folds of g-CN and BM. The enhanced photoelectrocatalytic effect was attributed to the boosted visible light adsorption ability, recombination suppression of photogenerated carriers and accelerated charge transfer process of the heterojunction. Radical capture experiments and electron spin-resonance (ESR) results revealed that the hydroxyl radical (•OH), superoxide radical (•O2-) and hole (h+) dominated the CQ degradation. Furthermore, the CQ degradation pathway and toxicity evaluation of intermediates were proposed based on DFT calculation and LC-MS identification.