In situ construction of Ti3C2 MXene/TiO2 heterojunctions with efficient piezoelectric catalytic activity for high antibacterial performance

Abstract

The practical application of two-dimensional MXenes in the field of piezoelectric catalytic antifouling is hindered by their inherent instability and insufficient active sites. To address this, we report a strategy for functionalizing Ti₃C₂ MXene via in situ alkaline oxidation, specifically by reconfiguring the surface termination groups and terminating the MXene surface with TiO₂, to construct a heterostructure Ti₃C₂ MXene/TiO₂ piezocatalyst. This approach not only stabilized the MXene structure but also significantly enhanced its piezocatalytic activity. The uniform growth of TiO₂ nanowires on MXene layers, as confirmed by SEM and XRD, created a tightly coupled 1D/2D heterointerface. The optimized heterojunction exhibits excellent piezoelectric catalytic antibacterial efficiency under dark conditions, achieving antibacterial rates of 95.94% (Escherichia coli), 96.83% (Pseudomonas aeruginosa), and 78.2% (Staphylococcus aureus). It also demonstrates a high transient current density (21.89 μA cm⁻²) and outstanding cycling stability (the performance degradation was less than 7% even after 5 cycles). Combined experimental and DFT analyses reveal that the built-in electric field and work function difference at the heterojunction interface efficiently drive the charge separation and transfer, with ˙O₂⁻ and ˙OH being the primary reactive species. This work demonstrates a viable route for the performance enhancement and functional expansion of MXene, providing an effective reference for its application in mechanically driven antifouling technologies.