Designed S‐Scheme FeCo ₂ O ₄ /g‐C ₃ N ₄ Heterojunction for Photocatalytic Activation of Peroxymonosulfate to Degrade polyethylene Terephthalate Plastic

To address the escalating pollution from polyethylene terephthalate (PET) microplastics, this study constructs an S‐scheme heterojunction photocatalyst, FeCo 2 O 4 /g‐C 3 N 4 (FCO/CN). The system achieves efficient synergistic degradation of PET by coupling visible‐light‐driven photocatalysis with peroxymonosulfate (PMS) activation. Density functional theory (DFT) calculations confirm that the heterojunction interface modulated the electronic structure, leading to hole accumulation on CN and electron accumulation on FCO, with the built‐in electric field significantly promoting charge separation. This interface also enhances the adsorption of PMS on Co/Fe active sites, lowering the energy barrier for generating SO 4 •− and thereby facilitating the cooperative production of multiple reactive oxygen species, including SO 4 •− , •OH, and •O 2 •− . Under optimized conditions, a PET degradation rate of 84.49% is attained within 6 h. Radical quenching experiments and ESR spectroscopy identified SO 4 •− as the key reactive species, and a plausible PET mineralization pathway is proposed. This work presents an efficient strategy for plastic pollution remediation and advances the understanding of S‐scheme heterojunction design and photocatalysis‐coupled PMS activation mechanisms.