Hierarchical Cu-doped MoS2 microspheres with efficient visible-light-driven peroxymonosulfate activation for micropollutant degradation: Nanostructure engineering and reaction mechanism

Transition metal doping and nanostructure engineering are effective strategies to overcome the limitations of photocatalysts in peroxomonosulfate (PMS) activation. In this study, Cu-doped MoS₂ with a hierarchical microspheric architecture was synthesized via a one-step hydrothermal method and employed for tetracycline (TC) degradation through PMS activation. Under visible light irradiation, the Cu_0.06-MoS₂ catalyst achieved an 86.2% TC removal efficiency within 40 min, which was 2.3 times higher than that of pristine MoS₂. The effects of various operation parameters, including initial PMS concentration, reaction temperature, solution pH, and coexisting inorganic anions on the TC degradation efficiency were thoroughly investigated. Characterization results and theoretical calculations demonstrated that the redox cycles of Cu²⁺/Cu⁺ and Mo⁶⁺/Mo⁴⁺, as well as the 3D microspheric structure of Cu_0.06-MoS₂, support its ultra-high charge transfer capability and abundant exposure of active sites, thereby promoting efficient photocatalytic activation of PMS for TC degradation. Reactive species quenching experiments and EPR analysis revealed that ·O₂^-, •OH, and SO₄^•- are the primary reactive oxygen species involved in TC degradation. This study provides a promising direction for the development of highly efficient micropollutant degradation utilizing transition metals-modified sulfide photocatalysts with a 3D architecture.