MOFs-Derived Oxygen-Vacancy-Rich Cu-Cu_xO/TiO₂ with Dynamic Redox Cycling for Steering Hole-Driven PMS Activation

The efficiency of peroxymonosulfate (PMS) activation in photocatalytic processes critically depends on the regulation of electron transfer from generation to utilization. Herein, a holistic electron transfer pathway is constructed within a metal-organic frameworks (MOFs)-derived Cu-Cu_xO/TiO₂ composite to achieve superior PMS activation. The incorporated Cu species serve as dynamic redox mediators, enabling an efficient non-photoinduced electron transfer pathway via Cu⁰&Cuⁿ⁺ cycling. Simultaneously, the Cu-induced bandgap narrowing and abundant oxygen vacancies significantly enhance visible-light absorption and facilitate the rapid trapping of photogenerated electrons. This synergy establishes a continuous and highly efficient electron transfer from photoexcitation to catalytic reaction. The optimized catalyst Cu-Cu_xO/TiO₂-2 delivers an exceptional tetracycline hydrochloride (TC) degradation rate constant of 38.26 × 10^-3 min^-1, representing a 2.04-fold enhancement over pristine TiO₂ (18.74 × 10^-3 min^-1). Mechanistic studies confirm that the radical (^•OH/^•SO₄ ^-) and non-radical (h⁺) pathways function synergistically in the Cu-Cu_xO/TiO₂-2/PMS system, collectively enabling highly efficient TC degradation. Three plausible degradation routes are proposed based on intermediates identification and density functional theory (DFT) calculations. Furthermore, economic analysis is conducted to transition from mechanistic insight to practical value, assessing the commercial potential of the Cu-Cu_xO/TiO₂-2/PMS photodegradation system. This work provides valuable insights into the design of efficient composite catalysts through regulated electron transfer via dynamic redox cycling coupled with oxygen vacancy engineering.