Kinetic analysis and mechanism study on the photocatalytic degradation of 2,4-dinitrophenylhydrazine over surface plasmonic Ag/Cu/TiO₂ composite

Ag/Cu/TiO₂ composite was successfully synthesized by a one-step solvothermal process combined with chemical reduction method for photocatalytic degradation of 2,4-dinitrophenylhydrazine. The degradation experiments show that the composite exhibits optimal degradation efficiency with the loading of 2 wt% Ag and 1 wt% Cu. The degradation rate can reach 85.9% within 70 min under simulated solar light irradiation. Non-linear least squares fitting indicates that the degradation process follows pseudo-first-order kinetic model, and the apparent activation energy is 19.97 ± 2.07 kJ mol⁻¹. The degradation mechanism analysis demonstrates that superoxide and hydroxyl radicals play the main role in the degradation process. In addition, possible degradation pathway was proposed based on the liquid chromatography–mass spectrometry (LC–MS) analysis and theory calculation.