Efficient photoelectrochemical remediation of tetracycline via a polymer quantum dot-sensitized S-scheme Cu2O/C3N4 heterojunction

The rise of antibiotic resistance, driven by the widespread use of antibiotics, is a critical global challenge, creating an urgent need for effective wastewater treatment technologies. To address this, we developed an advanced photoanode for solar-driven remediation. The system was architecturally designed via electrophoretic deposition, anchoring n-type protonated graphitic carbon nitride nanosheets decorated with n-type Cu2O onto an anodized stainless-steel mesh. This construct was further sensitized with polymeric quantum dots (PQDs) to significantly enhance light absorption and charge transfer. Comprehensive characterization and photoelectrochemical analyses confirmed the successful fabrication and optimal optoelectronic properties. The PQDs were pivotal in establishing an S-scheme heterojunction, which effectively suppressed electron-hole recombination and created a synergistic interface between the components. The system's robustness was validated through Mott-Schottky analysis, impedance spectroscopy, kinetic modeling, scavenger tests, and DFT calculations. The resulting stable and reusable photoanode demonstrated exceptional performance, harnessing solar energy to generate potent hydroxyl radicals. This achieved 98.65% degradation of tetracycline and a significant 75.70% reduction in total organic carbon, indicating efficient mineralization. This work presents a highly effective and sustainable approach for purifying antibiotic-contaminated wastewater, contributing directly to environmental protection