Enhancement mechanism of full-solar-spectrum catalytic activity of g-C3N4-x/Bi/Bi2O2(CO3)1-x(Br, I)x heterojunction: The roles of plasma Bi and oxygen vacancies

Abstract

In this work, plasma Bi and oxygen vacancies (OVs) co-modified g-C3N4-x/Bi/Bi2O2(CO3)1-x(Br, I)x heterojunction was prepared via solvothermal reaction. The formation of OVs was promoted induced by polarization charge transfer, while the deposition of Bi was attributed to the esterification between CH3CH2OH and NaBiO3 and subsequent anoxic thermal reduction. The increased OVs concentration improved the adsorption performance of tetracycline (TC), meanwhile promoting the separation of hot carriers of plasma Bi by trapping hot electrons. The dissociated hot holes directly drove near-infrared (NIR) photocatalytic reaction. The deactivation of OVs in Bi2O2(CO3)1-x(Br, I)x was inhibited due to the deposition of Bi, and the Z-scheme mechanism was achieved with Bi as electron mediator. Hence, g-C3N4-x/Bi/Bi2O2(CO3)1-x(Br, I)x showed enhanced full-spectrum catalytic activity and excellent stability. 84.6%/70.0% and 79.33%/70.19% of TC and total organic carbon could be removed by the optimal heterojunction under simulated sunlight/NIR light irradiation, and the NO removal rate under visible light irradiation was as high as 76.7%. This work revealed the different roles of OVs and metal in defect-mediated heterojunction, and provided a feasible method to prepare full-spectrum response photocatalysts with high activity and stability.