Ag Nanoparticles–Doped Co ₃ O ₄ Composite Photocatalyst for UV Light–Assisted Degradation of Polystyrene Nanoplastics

Nanoplastics are a significant environmental threat due to their persistence and toxicity. In this study, we prepared a kind of Ag-doped Co₃O₄ catalyst using a coprecipitation method, aimed at enhancing its photocatalytic degradation efficiency of polystyrene nanoplastics under UV irradiation. Morphology and component of Ag/Co₃O₄ have been investigated by XRD, FTIR, TEM, and BET analysis. The information of absorption and energy levels for catalysts is provided by UV-vis DRS, Tauc plots, and Mott-Schottky curves. Charge-transfer abilities for catalysts have been analyzed by PL spectra and EIS. The photocatalytic activities of Ag nanoparticles (Ag NPs), Co₃O₄, and Ag/Co₃O₄ have been carefully evaluated in this work. Ag/Co₃O₄ photocatalyst exhibits the highest degradation efficiency with a kinetic rate constant of 0.0086 min⁻ ¹, outperforming that of Co₃O₄ (0.0062 min⁻ ¹) and Ag NPs (0.0036 min⁻ ¹). The degradation efficiencies for catalysts have also been assessed under varying pH conditions (neutral, acidic, and basic). Among them, Ag/Co₃O₄ shows a notable degradation efficiency of 61% at pH 7, compared to 46% for Co₃O₄ and 30% for Ag NPs. In addition, the intermediates and final products have also been discussed according to Py-GC/MS results.