Simultaneous inactivation of Microcystis aeruginosa and degradation of microcystin-LR via a p-p ZnCo2O4/Cu2O S-scheme photocatalyst: Mechanism and "Adsorption-Oxidation-Lysis" pathway.

The remediation of cyanobacterial harmful algal blooms faces a critical challenge: balancing rapid inactivation with the elimination of secondary pollution caused by released toxins. To address this, a novel p-p type S-scheme heterojunction, comprising spinel ZnCo2O4 nanoparticles anchored on cubic Cu2O (7.5ZCO/CO), was rationally constructed via an ethanol-assisted interfacial engineering strategy. Advanced characterization, including in-situ irradiated XPS and Kelvin Probe Force Microscopy, provided unambiguous atomic-level evidence for a built-in electric field that drives a robust, directional S-scheme charge transfer. Under simulated solar irradiation, the optimized composite demonstrated superior dual-functional performance, achieving 71% inactivation efficiency against Microcystis aeruginosa within 180 min. Mechanistic investigations revealed a holistic "Adsorption-Oxidation-Lysis" cascading pathway, initiated by the oxidative damage to the photosynthetic system (indicated by a 67% reduction in Chlorophyll a) and culminating in irreversible membrane rupture. Crucially, Liquid Chromatography-Tandem Mass Spectrometry analysis confirmed the authentic detoxification of the released Microcystin-LR (∼59% degradation) via targeted oxidative cleavage of its hepatotoxic Adda side chain. Furthermore, the system maintained highly competitive inactivation efficiencies in complex natural matrices, including actual Lake Erhai water. This work establishes the 7.5ZCO/CO S-scheme system as a robust and ecologically safe technology for the integrated inactivation and detoxification of eutrophic waters.