Pt/PtO_x Nanoparticle-Decorated BiVO₄ Pinelike Structure for Enhanced Sulfamethoxazole Mineralization under Visible Light Irradiation

Effective charge separation is an important factor for enhancing the activity of BiVO4 photocatalysts. In this study, we present selective and random deposition of Pt/PtOx nanoparticles on the surface of BiVO4 pinelike architectures (Pt/PtOx/BiVO4) to improve charge separation. The effectiveness of the charge separation achieved through noble metal decoration depends on the specific loading location on the surface of the BiVO4 crystal. The photocatalytic activity of the Pt/PtOx/BiVO4 samples was investigated through the photodegradation of sulfamethoxazole (SMX) under visible light irradiation. Pt/PtOx decorated on the BiVO4 {040} facet catalyst (Pt/PtOx/BiVO4-PD) resulted in higher approximately 1.5 times higher SMX photodegradation compared to that of Pt/PtOx randomly decorated Pt/PtOx on BiVO4 (Pt/PtOx/BiVO4-R) and approximately 23 times higher than that of bare BiVO4. In addition, Pt/PtOx/BiVO4-PD achieved 83% total organic carbon (TOC) removal, whereas Pt/PtOx/BiVO4-R and BiVO4 achieved TOC removal rates of 68 and 8%, respectively. The three-dimensional excitation-emission matrix fluorescence spectra further confirmed the high degree of mineralization achieved by the Pt/PtOx/BiVO4-PD. The establishment of a Schottky barrier at the interface between the Pt/PtOx and BiVO4 {040} facets provides an efficient route for transferring and accumulating photoinduced electrons from the conduction band of BiVO4 to the Pt/PtOx nanoparticles. The holes (h+) and superoxide (•O2–) radicals were identified as the primary active species during the SMX elimination reaction over the Pt/PtOx/BiVO4-PD photocatalyst. A liquid chromatography–mass spectroscopy system was employed to analyze the intermediate products of SMX present in the solution following the reaction. This investigation can provide offer insights into the development of heterojunction photocatalysts for antibiotic photodegradation in aqueous media through the synthesis of a heterojunction photocatalyst.