Boosting dissolved oxygen utilization by oriented electron transfer on dual-site S-scheme heterojunction for low-H2O2-consumption photo-fenton reaction

Abstract

The photo-Fenton reaction integrates the advantages of photocatalysis and Fenton process, but its catalytic efficiency for antibiotic pollution control relies heavily on the dosage of H2O2, whose production suffers from high energy input and intensive pollution. Herein, a dual-site S-scheme heterojunction is constructed by assembly of phosphate-modified TiO2 and Fe(II) phthalocyanine (FePc). Compared to the reported catalysts, this composite exhibits much higher first-order kinetic rate constant up to 0.275 min−1 in ofloxacin degradation but consumes 5–250 times less amount of H2O2. Experimental and theoretical evidences demonstrate that H2O2 molecules prefer to bind onto phosphate sites through Hbonds and donate electrons followed by its dissociation into O2−. Driven by the internal electric field, these electrons quickly flow into FePc sites to reduce adsorbed dissolved oxygen (O2) into O2−. Such dual-site configuration and oriented electron transfer eliminate the competitive reaction between O2 and H2O2. This work provides an ingenious strategy to slash H2O2 consumption by boosting O2 utilization, synergistically producing vast O2− for highly efficient pollutant degradation.