Bulk polarization fields and interfacial electron sink in MXene-modified iodine-doped Bi4Ti3O12 enhance piezocatalytic H2O2 generation

Piezocatalytic hydrogen peroxide (H₂O₂) production holds promise as a sustainable technology, but its practicability is hindered by inadequate polarization fields, sluggish charge transport, and rapid bulk carrier recombination. Herein, we propose a catalyst-design strategy integrating bulk iodine doping with surface MXene cocatalyst coupling in a typical piezoelectric bismuth titanate (Bi₄Ti₃O₁₂, BTO). This design generates intensified bulk polarization fields that markedly suppress electron-hole recombination, while MXene functions as an efficient interfacial electron sink, significantly reducing surface kinetic barriers by facilitating electron transfer for the oxygen reduction reaction (ORR). The optimized iodine-doped MXene-coupled BTO (MBTO-I) catalyst demonstrates a piezocatalytic H₂O₂ production rate of 5890 µmol g⁻¹ h⁻¹ under ambient conditions without any sacrificial agents. Theoretical calculations and advanced characterization techniques reveal that iodine doping effectively lowers energy barriers for *OH intermediate formation and stabilizes O-H bonds, while MXene coupling significantly improves interfacial charge transfer and accelerates the ORR kinetics. Furthermore, the produced H₂O₂ was successfully employed for bacterial sterilization and rapid degradation of pollutants. Subsequent chemical analyses and biological assessments confirm a substantial reduction in the toxicity of sulfamethoxazole (SMX) degradation products, highlighting the catalyst's considerable potential for environmental remediation applications.