Photocatalysis synergistically enhanced Fenton-like process: Photogenerated electron-mediated sustainable dynamic Fe(III)/Fe(II) redox cycle

Highly efficient synergistic catalysis is achieved by constructing a dual two-dimensional MoS₂/ZnFe-layered double hydroxide composite (2D/2D MoS₂@ZnFe-LDH) and coupling photocatalysis and Fenton-like process to address the drawbacks of the traditional Fenton-like system. The layered structure of ZnFe-LDH enables firm anchoring and uniform dispersion of Fe active sites within the layers without forming clusters, meanwhile enhancing mass transfer efficiency and accelerating both peroxymonosulfate (PMS) adsorption and reactive oxygen species desorption. The constructed 2D/2D heterojunction strengthens interfacial covalent bonding and compatibility, shortens the migration distance of photogenerated carriers, thereby significantly improving the charge separation efficiency, which accelerates the Fe(III)/Fe(II) cycle for sustainable catalysis across a broad pH range without Fe sludge aggregation. Comprehensive analysis of EPR, in-situ XPS, quenching and probe experiments, and DFT indicates that PMS is efficiently adsorbed onto Fe sites and reduced to generate SO₄^•- and •OH. Meanwhile, further characterization combining EPR, determination of surface Fe(II) concentration, in-situ photoelectrochemical and Raman measurements, XPS and DFT confirms that photogenerated electron can simultaneously reduce Fe(III) and promote radical desorption, thereby achieving sustainable catalysis. Hence, the system achieves complete phenol removal with a high synergistic index and figure of merit of 9.69 and 2.62 × 10⁻¹⁰ mol·L⁻¹·h⁻¹·g⁻¹·J⁻¹, respectively. It also operates efficiently in various complex water matrices and maintains stable operation over 24 h in the continuous-flow reactor, demonstrating strong anti-interference capability without any biological toxicity. In conclusion, this study proposes a new strategy to develop for developing high-performance and sustainable photo-Fenton-like dual-system.