Ti3C2 quantum dots modified on BiOBr surface for sewage disposal: The induction of the piezo-phototronic effect from edge to whole

The constructed piezo-photocatalytic system of TCQDs/BiOBr composites reveals the stable coupling (piezo-phototronic effect) of piezocatalysis and photocatalytic heterojunction. TCQDs acts as an electronic acceptor to induce the piezoelectric field to diffuse from the edge to the center, which greatly enhances the overall piezoelectric photocatalytic performance. The 1 wt% TCQDs/BiOBr piezo-photocatalysts reveal satisfying catalytic activity, and its degradation rate is 5.29 and 3.48 times of sole piezocatalytic process and photocatalytic reaction, respectively. Besides, the rate reaction constant is 4.8 times that of the optimal Ti 3 C 2 MXene/BiOBr. The enhanced catalytic performance gives the credit to (i) built-in piezoelectric field is generated by the mechanical stretch, which promotes the transfer of photo-electrons; (ii) the introduction of 0D TCQDs is deposited on the surface of BiOBr, which expands the piezo-phototronic effect from the edge of nanosheet to entire and obstruct the recombination of photo-excited electron-hole pairs. Radical trapping tests proves that active free radicals (•O 2– , h + , and •OH) are triggered and engaged in the piezoelectric photocatalytic system. This work also illustrates that the dual-energy-driven (optical and mechanical energy) piezo-photocatalytic system have tremendous potential to design efficient catalysts in the treat sewage. • The piezo-phototronic effect is stimulated by optical and mechanical energy. • TCQDs expand the piezo-phototronic effect from the edge to entire BiOBr nanosheet. • The piezoelectric response signal of TCBB-3 is enhanced compared with pure BiOBr. • Synergistic effect of piezo-photocatalytic system has potential to decompose organic pollutant. Piezo-photocatalytic system of two-dimensional (2D) composite can make the utmost of light and mechanic energy to degrade the contaminant and renovate our environment. Herein, we report a Ti 3 C 2 quantum dots (TCQDs) decoration strategy that fully activates the piezo-phototronic effect in the piezo-photocatalytic system, extending the piezoelectric field from the edge of the nanosheet to the whole. The edge piezoelectric effect generated by the vibration of BiOBr nanosheets is extended to entire nanosheet by electron acceptor TCQDs, which further reduces the effect of recombinant of photo-induced carriers at the heterogeneous interface. The electron enrichment of TCQDs gives rise to admirable piezo-photocatalytic performance compared to different catalytic system for methyl violet (MV) decomposition. Especially, the 1 wt% TCQDs/BiOBr sample presents inspiring degradation rate (99.8%, 48 min), which is 5.29 and 3.48 times of the sole photocatalytic system and piezocatalytic reaction. This work provides a new view for activating the piezo-phototronic effect of whole nanosheets by quantum dots, which has great potential for rapid elimination of organic pollutants and preparation of efficient catalytic system.