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

The photo-Fenton reaction integrates the advantages of photocatalysis and Fenton process, but its catalytic ef-ficiency 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 H-bonds and donate electrons followed by its dissociation into center dot O2- . Driven by the internal electric field, these electrons quickly flow into FePc sites to reduce adsorbed dissolved oxygen (O2) into center dot O2- . Such dual-site configuration and oriented electron transfer eliminate the competitive re-action between O2 and H2O2. This work provides an ingenious strategy to slash H2O2 consumption by boosting O2 utilization, synergistically producing vast center dot O2- for highly efficient pollutant degradation.