0D–2D Fe₂O₃/Boron-Doped g-C₃N₄ S-Scheme Exciton Engineering for Photocatalytic H₂O₂ Production and Photo-Fenton Recalcitrant-Pollutant Detoxification: Kinetics, Influencing Factors, and Mechanism

Abstract

Step-scheme (S-scheme) heterojunctions comprising two semiconductors having two sets of charge carriers at different sites with an outstanding redox capability have emerged as a prospective tactic for H2O2 production and antibiotic remediation. Herein, 0D/2D Fe2O3 QD/B-g-C3N4 (F-BN) was successfully fabricated via in situ nucleation of Fe2O3 quantum dots (FQDs) over boron-doped g-C3N4 (BCN) sheets for H2O2 production and photo-Fenton amoxicillin (AMX) degradation. Empirical results demonstrate that the F-BN composite shows a superior catalytic activity compared to the parent material and the optimized 3F-BN attains the best activity for H2O2 generation (729 μmol and solar-to-chemical conversion efficiency (SCC) of 0.12%) and photo-Fenton AMX degradation (93%) with a “k” of 0.0891 min–1, which is 3.34 and 7.01 times higher than those of the pristine materials. The outstanding activity could be attributed to effective separation and utilization of excitons through the S-scheme transfer pathway. Moreover, charge transfer through the S-scheme transfer corridor along with continuous Fe3+/Fe2+ shuttling is responsible for the effective photo-Fenton activity. Additionally, the influence of the variation of experimental conditions is also studied in detail. The high photocurrent, lower EIS semicircle, and low PL intensity indicate effective separation efficiency of e–/h+ in the 3F-BN material. Furthermore, the scavenging experiment and terephthalic acid (TA), nitro blue tetrazolium chloride (NBT), and EPR measurements not only evidence that the generated reactive oxygen species (•OH and •O2–) participated in photocatalytic activities but also validate the S-scheme charge-transfer mechanism which is further confirmed from in-situ XPS analysis.