MnO₂/Cu₂O S-scheme heterojunction enabling photothermal-enhanced peracetic acid activation for efficient...

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have emerged as promising strategies for antibiotic removal. However, the efficiency of PAA-based AOPs remains constrained due to rapid charge carrier recombination and the overlooked contribution of photothermal effects to PAA activation. Herein, MnO₂/Cu₂O S-scheme heterojunctions were constructed through a hydrothermal-precipitation method, enabling the synergistic use of photothermal and photocatalytic effects for enhanced PAA activation. Notably, the MOCO-0.6/PAA/Vis system achieved 96.17% MTZ removal within 30 min, exhibiting an apparent rate constant (k_oβs) that was 1.89 times higher than that of the temperature-controlled system and 11.75 times higher than that under dark conditions, respectively. Infrared thermography revealed that the photothermal response of MnO₂ and Cu₂O elevated the reaction temperature, thereby reducing the activation energy barrier and accelerating the oxidation process. Crucially, the S-scheme heterojunction structure inhibited charge recombination and simultaneously promoted the Mn(IV)/Mn(III) and Cu(I)/Cu(II) redox processes during the reaction. Furthermore, the MOCO-0.6/PAA/Vis system maintained high MTZ removal efficiencies (>80%) in tap water, lake water, simulated chemical wastewater, and simulated hospital wastewater, demonstrating its strong resistance to matrix interference and applicability in complex environmental waters. LC-MS analysis combined with mung bean seed germination tests was further conducted to evaluate the toxicity evolution of the degraded solution. These findings highlight the synergistic contribution of photothermal-enhanced PAA activation and S-scheme-mediated photocatalysis in accelerating antibiotic degradation, providing a promising strategy for the practical treatment of antibiotic-contaminated wastewater under environmentally relevant conditions.