Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency o...Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency of photocatalysts.Bi_(2)Fe_(4)O_(9),a narrow gap semiconductor with piezoelectric effect,was prepared by a hydrothermal synthesis method for the degradation of reactive dye KN-R.The results show that the degradation efficiency of KN-R can be significantly improved by piezo-photocatalysis,and the degradation rate constant of piezo-photocatalysis k_(pi-ph)is about 3.4 times as large as the degradation rate constant of piezoelectric catalysis k_(pi)and about 2.6 times as large as the degradation rate constant of photocatalysis k_(ph).At a pH value of 3 and a lower KN-R mass concentration(60 mg/L),a higher degradation efficiency(98.5%)is achieved.CO_(3)^(2-)and cationic surfactant(CTAB)inhibit the degradation of KN-R.It is proved that the contributions of different active species to the degradation of KN-R follow the order:·OH,·O_(2)^(-),h^(+),and^(1)O_(2).The possible mechanism of piezo-photocatalytic degradation of KN-R was discussed.The photoexcitation generates a large amount of free charges,and the piezoelectric effect modulates the energy band structure of Bi_(2)Fe_(4)O_(9)and promotes the separation of photogenerated electron-hole pairs.The synergistic effect of the two factors significantly improves the degradation efficiency of KN-R.展开更多
文摘Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency of photocatalysts.Bi_(2)Fe_(4)O_(9),a narrow gap semiconductor with piezoelectric effect,was prepared by a hydrothermal synthesis method for the degradation of reactive dye KN-R.The results show that the degradation efficiency of KN-R can be significantly improved by piezo-photocatalysis,and the degradation rate constant of piezo-photocatalysis k_(pi-ph)is about 3.4 times as large as the degradation rate constant of piezoelectric catalysis k_(pi)and about 2.6 times as large as the degradation rate constant of photocatalysis k_(ph).At a pH value of 3 and a lower KN-R mass concentration(60 mg/L),a higher degradation efficiency(98.5%)is achieved.CO_(3)^(2-)and cationic surfactant(CTAB)inhibit the degradation of KN-R.It is proved that the contributions of different active species to the degradation of KN-R follow the order:·OH,·O_(2)^(-),h^(+),and^(1)O_(2).The possible mechanism of piezo-photocatalytic degradation of KN-R was discussed.The photoexcitation generates a large amount of free charges,and the piezoelectric effect modulates the energy band structure of Bi_(2)Fe_(4)O_(9)and promotes the separation of photogenerated electron-hole pairs.The synergistic effect of the two factors significantly improves the degradation efficiency of KN-R.
