Improved piezo-assisted photocatalytic performance of Br-doped g-C3N4 toward organic dyes degradation

• Br-doped g-C 3 N 4 (BrCN) catalyst was assembled for piezo-assisted photocatalytic degradation of dyes. • Compared with the piezo- and photo-catalytic, the piezophotocatalytic activity of BrCN was enhanced. • The photocharge recombination was prevented by the piezoelectric-polarization effect. • The recyclability study of BrCN confirmed the high stability behavior for six succeeding piezophotocatalytic rounds. Herein, bromine-doped graphitic-like carbon nitride (Br-doped g-C 3 N 4 ) have been synthesized for improved piezo-assisted photocatalytic decomposition of Congo red (CR) and Malachite Green Oxalate (MGO) dyes under sonication and visible illumination. Compared with the piezocatalysis and photocatalysis, the piezo-assisted photocatalytic decomposition process demonstrated higher performance, degrading 94.9 % and 87.6 % of MGO and CR, respectively within 120 min. The boosted visible-light absorption after Br doping coupled with the highly piezoelectric polarizability impact of the g-C 3 N 4 sample contributes to the high separation rates of the photogenerated carriers, thus enhancing the overall degradation productivity. The piezo-assisted photocatalytic decomposition mechanism has been deliberated, and approved by trapping tests. Moreover, the reusability experiments showed the outstanding stability of fabricated Br-doped g-C 3 N 4 after five consecutive rounds. Doping Br in g-C 3 N 4 provides a new strategy for constructing g-C 3 N 4 -based catalysts for synergistic piezophotocatalytic processes.