Xiao-shan Miao,Jia-wei Sun,Fu Ma,Hong-jian Zhao,Yan Zhou,Zheng-bing Han,Xu Li
Zn–SnO 2 /BiOBr, a novel heterojunction material for photocatalytic dye degradation, was synthesized successfully using the one-step hydrothermal method. The formation of the heterojunction enhanced the vacancy coupling effect. The photocatalytic experiment results showed that the degradation rate of Rhodamine B (RhB) due to 0.3Zn–SnO 2 /BiOBr (the heterojunction formed when the molar ratio of Zn–SnO 2 to BiOBr was 0.3) within 15 min was 9.27 and 476.9 times that of BiOBr and Zn–SnO 2 , respectively. Additionally, the degradation rate of basic fuchsin (BF) due to 0.3Zn–SnO 2 /BiOBr was 4.2 and 21.9 times that of BiOBr and Zn–SnO 2 , respectively. The significantly improved photocatalytic performance was because many oxygen vacancies in Zn–SnO 2 /BiOBr collaborated with the type-II heterojunction to promote a narrow bandgap value efficiently, increasing the photogenerated electrons (e – ) and hole (h + ), an increased charge separation efficiency under visible light, and favored the photocatalytic degradation of dyes.
The establishment of p–n heterojunction between semiconductors is an effective means to improve the performance of semiconductor photocatalysts. For the first time, we synthesize SnO2/BiOBr heterojunction photocatalysts using a one-step hydrothermal method. Systematic material characterizations suggest that the photocatalysts consist of irregular BiOBr nanosheets with the length about 200 nm and width about 150 nm, and SnO2 nanoparticles are anchored uniformly onto the nanosheets. Most importantly, electrochemical characterizations including transient photocurrent profiles and electrochemical impedance spectra suggest that SnO2/BiOBr heterojunctions are created, which facilitates the charge separation and transfer efficiency of photogenerated charge carriers. As such, SnO2/BiOBr photocatalysts exhibit remarkable photocatalytic activities in terms of degrading a series of organic pollutants. Radical trapping experiments and electron spin resonance spectra suggest that superoxide radicals (•O2–) and hydroxyl radicals (•OH) are primary medium species running through the photocatalytic degradation process and enhanced photocatalytic performance.
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