• 关键词：Bi修饰BiOBr/g-C₃N₄  异质结  形貌调控  可见光催化性能  光降解机理

• 基金项目：国家自然科学基金（No.51378129）；广东省自然科学基金（No.2017A030313321，2015A030313494）；广东省高教厅-普通高校特色创新类项目（No.2016KTSCX035）

• 李冬梅
• 广东工业大学, 土木与交通工程学院, 广州 510006

• 梁奕聪
• 广东工业大学, 土木与交通工程学院, 广州 510006

• 卓涌淇
• 中山大学, 材料科学与工程学院, 广州 510275

• 邓玥
• 珠海一中附属实验学校, 珠海 519000

• 曾庆洋
• 约克学校, 美国加州 93940

• 冯力
• 广东工业大学, 土木与交通工程学院, 广州 510006

• 尤炜弘
• 广东工业大学, 土木与交通工程学院, 广州 510006

• 摘要：以尿素为氮化碳（g-C₃N₄）合成的前驱体，柠檬酸（CA）作为还原剂，以一步溶剂热法制备铋修饰BiOBr/g-C₃N₄异质结型复合光催化剂（简称Bi/BiOBr/g-C₃N₄）.通过调控CA的投加量，实现了对Bi/BiOBr/g-C₃N₄可见光催化的可控制备，并以RhB为目标污染物研究其光催化活性.结果表明：①被还原在BiOBr表面上的Bi金属含量随还原剂CA投加量增加而增加，CA最佳投加量为2 mmol，Bi/BiOBr/g-C₃N₄的光生载流子的分离效率最高、禁带宽度最窄（2.43 eV）.而未采用CA改性的BiOBr/g-C₃N₄，其禁带宽度为2.8 eV.②投加CA能调控BiOBr形貌（如结晶度、尺寸大小以及晶粒平均厚度），进而调控其光催化活性.当CA投加量为2 mmol时，BiOBr纳米微球大小适中，结晶度最高，晶粒平均厚度最小.③Bi修饰BiOBr/g-C₃N₄光催化剂对RhB的可见光降解率高达99.8%，其光催化降解速率达到0.097 k·min^-1，是BiOBr/g-C₃N₄光催化速率（0.026 k·min^-1）的3.73倍.④Bi/BiOBr/g-C₃N₄异质结光降解机理是：在Bi金属等离子体效应、BiOBr表面氧空缺与异质结的协同作用下，提高了Bi/BiOBr/g-C₃N₄异质结对可见光吸收能力和光生载流子的分离效率，从而实现对RhB的高效降解.

• Abstract：Taking urea as a precursor for the preparation of carbon nitride (g-C₃N₄) and citric acid (CA) as a reducing agent, the composite photocatalyst Bi-amended BiOBr/g-C₃N₄ heterojunction (Bi/BiOBr/g-C₃N₄) was synthesized by taking one-step solvothermal method. By adjusting the dosage of CA, the visible light responsive activity of the Bi/BiOBr/g-C₃N₄ was optimized and verified in the process of degrading the dying pollutant RhB. The results were shown below:with the addition of the dosage of the reducing agent CA, the content of the metal Bi being reduced on the surface of BiOBr increased. When the dosage of CA was up to the optimum (2 mmol), the separation efficiency of the photoinduced electron-hole pairs of Bi/BiOBr/g-C₃N₄ reached the highest and the band gap (2.43 eV) was the narrowest, while the BiOBr/g-C₃N₄ band gap was 2.8 eV. ②The reducing agent CA affected the crystallinity, size and average thickness of BiOBr. When the dosage of CA was 2mmol, the size of BiOBr nanospheres was moderate, its crystallinity was the highest, and its average thickness was the smallest. ③ under the optimum dosage of CA, the Bi/BiOBr/g-C₃N₄ demonstrated the highest visible light degradation efficiency of RhB (99.8%), and its photocatalytic degradation rate reached 0.097 k·min^-1, which was 3.73 times of that of BiOBr/g-C₃N₄ (0.026 k·min^-1).④The photodegradation mechanism of Bi/BiOBr/g-C₃N₄ heterojunction was that the synergistic effect between Bi metal plasma, surface oxygen vacancy of BiOBr and heterojunction. The synergistic effect promoted the separation rate of the photoinduced electron-hole pairs markedly, thereby Bi/BiOBr/g-C₃N₄ achieved high degradation efficiency of RhB.

• Key words：Bi-decorated BiOBr/g-C₃N₄  heterojunction  morphological control  visible light catalytic activity  photodegradation performance

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