Boosted synergistic piezo/photo-catalytic effect of g-C3N4-immobilized phosphotungstic acid heterojunctions for degradation of organic contaminants

Recently, the coupling of photocatalysis with piezocatalysis has become a vital research area and has attracted much attention for the highly efficient decomposition of organic pollutants. Herein, g-C3N4-immobolized phosphotungstic acid (PTA/g-C3N4) piezophotocatalyst have been fabricated for boosted piezophotocatalytic degradation of Malachite Green Oxalate (MGO) dye. Compared with the photocatalytic and piezocatalytic processes, the piezophotocatalytic destruction process exhibited higher efficiency, completing >97.2 % MGO degradation within 90 min of visible-illumination and sonication conditions. The high redox ability of PTA and the piezoelectric polarizability effect of highly visible-light-responsive g-C3N4 piezophotocatalyst synergistically leads to high separation rate of photoproduced carriers, thus promoting the overall decomposition efficiency. The recommended mechanism for MGO piezophotocatalytic degradation has been discussed, and interpreted based on the trapping experiments. Furthermore, the reusability tests confirmed the high stability behavior of synthesized PTA/g-C3N4, dropping only from 97.2 % to 91.8 % after six successive piezophotocatalytic rounds.