Quantum-dot–mediated dual-defect interfaces enable high-efficiency solar purification coupled with hydrogen recovery

Photocatalytic hydrogen evolution and pollutant degradation are both promising strategies for clean energy production and environmental remediation, yet their integration for synchronous wastewater-to-energy conversion is fundamentally hindered by inefficient charge utilization and severe interfacial redox competition. Herein, a quantum-dot-bridged dual-defect interface engineering strategy is developed to synchronize photocatalytic oxidation and hydrogen evolution for wastewater-to-energy conversion. As a result, a hierarchical S-type heterostructure was constructed by integrating Ti₃C₂ MXene quantum dots with electron-storage capability, sulfur-vacancy-rich MoS₂, and oxygen-deficient CeO₂ (TMMC), which effectively accelerated interfacial charge transport. The optimized catalyst achieves a hydrogen evolution rate of 12.17 mmol g^-1 h^-1 with 98.6% norfloxacin removal and maintains high stability under continuous operation. In pollutant-containing systems, hydrogen production reaches 274.35 μmol g^-1 h^-1 and further increases to 405.93 μmol g^-1 h^-1 upon low-dose peroxymonosulfate addition. Mechanistically, Ce-O-Mo interfacial coupling induces asymmetric charge redistribution and a built-in electric field for directional carrier separation, while spatially separated sulfur and oxygen vacancies regulate proton reduction and oxidant activation, respectively, mitigating interfacial redox competition. This work establishes defect-coordinated interfacial engineering as a general paradigm for regulating charge utilization and reaction selectivity in integrated photocatalytic systems.