Multifaceted Synergism of Dual Active Sites in Oxygen Vacancies Enriched Plasmonic Ag-BiOI Nanosheets for Enhanced Piezo-Photocatalytic Degradation of Trimethoprim

Piezo-photocatalysis offers a promising, chemical-free approach for the efficient and scalable degradation of micropollutants. However, existing piezo-photocatalysts face challenges in optimizing their performance. In this study, oxygen vacancies (OVs) enriched BiOI nanosheets loaded with Ag nanoparticles (NPs) were synthesized to enhance Trimethoprim (TMP) degradation. The 15% Ag-BiOI demonstrated excellent performance, achieving a degradation efficiency of 97% within 60 min and a rate constant (k) of 0.1157 min^–1, which was significantly greater than the piezocatalytic (0.0476 min^–1) and photocatalytic (0.0784 min^–1) one. The synergistic interaction of OVs and Ag improved O₂ adsorption, creating dual active sites (Ag-OV) that promote the generation of active oxidative radicals, such as singlet oxygen (¹O₂) followed by superoxide radical (^·O₂^–) to degrade TMP. Likewise, OVs in BiOI regulated the piezoelectric field and enhanced TMP degradation by providing ample binding sites for surface interaction. The Ag acted as an electron transport channel, reducing charge carrier recombination, while its surface plasmon resonance effect modified the band gap of BiOI, promoting OVs generation to enhance visible light absorption. The toxicity assessment showed that the plasmon-induced piezo-phototronic effect of Ag-BiOI selectively reduces the toxicity of TMP intermediates by converting them into smaller, less-toxic compounds, proposing an ecofriendly approach for efficient and sustainable micropollutant degradation in wastewater treatment.