Universal quenching-reduction engineering of controllable Cu0/Cu+ active sites in 2D heterojunctions for enhanced Fenton-like catalysis.

The construction of stable Cu0/Cu+ active sites is essential for achieving high-performance copper-based Fenton-like catalysis. In this work, we develop a novel ethanol-mediated quenching reduction strategy synergistically integrated with rational two-dimensional structural engineering to precisely construct and stabilize Cu0/Cu+ pairs within a two-dimensional Cu-CuO/TiO2 heterojunction (CTO-Q). The approach leverages the transient thermal energy generated during rapid cooling to initiate ethanol dehydrogenation, during which in-situ electrons are released and subsequently reduce Cu2+ ions, thereby facilitating the controlled formation and long-term stabilization of coexisting Cu0/Cu+ species. Advanced spectroscopic characterizations provide direct evidence for the successful generation and chemical state stability of the Cu0/Cu+ active sites. The resultant CTO-Q catalyst exhibits superior PMS activation capability, achieving 95% removal of levofloxacin within 30 min, with an observed rate constant (kobs = 0.35 min-1) that is 3.89-fold higher than that of the conventional catalyst. Remarkably, the catalytic performance remains nearly unchanged after five consecutive cycles, maintaining approximately 95% degradation efficiency, which underscores its exceptional operational stability-attributable to a self-sustaining redox cycle that mitigates irreversible oxidation. The generality and scalability of this synthetic strategy are further validated by the successful fabrication of a family of two-dimensional Cu-based heterojunctions (Cu-CuO/CeO2, Cu-CuO/SiO2, and Cu-CuO/Al2O3). Critically, this methodology enables the valorization of Fenton sludge into a high-efficiency catalytic material, thereby establishing a direct link between advanced functional material design and sustainable environmental remediation.