Piezoelectricity Prompts Fenton Reaction Over a MoS₂/N-Doped Carbon-Coated BaTiO₃ Core-Shell Heterojunction

The conventional Fenton reaction has been identified as an effective approach for degrading heavy-metal complexes; however, its practical application is hampered by issues such as iron sludge formation, low H₂O₂ utilization efficiency, and consequently, limited degradation performance. We developed a piezocatalytic Fenton (PF) system based on a triple-layer core-shell heterojunction (MoS₂-NC@BTO) for the efficient decomplexation of Cu-organic complexes along with the recovery of Cu²⁺. This system enables the in situ generation and subsequent activation of H₂O₂ solely by the piezoelectric effect to produce hydroxyl radicals (•OH). The heterostructure was rationally constructed by growing MoS₂ nanosheets on an N-doped carbon layer-coated BaTiO₃ cubes (BTO), which facilitated decomplexation and copper recovery under ultrasonic vibration. The decomplexation rate constant of MoS₂-NC@BTO (0.122 min^-1) is 46.7 times greater than that of BTO (0.0026 min^-1), and it achieved complete decomplexation and 92% copper recovery efficiency within 60 min. Mechanistic investigations revealed that the core-shell heterojunction promotes charge carrier separation, thereby enhancing the yield of H₂O₂. Meanwhile, the MoS₂ nanosheets strengthen the piezoelectric effect, enabling efficient activation of H₂O₂ into •OH. Furthermore, the versatility and practical feasibility of the system were validated through the efficient treatment of six other Cu-organic complexes and real effluent matrices.