二维BiOBr/g-C_(3)N_(4)光催化材料的构建及性能研究

Construction and Photocatalytic Property of Two-Dimensional BiOBr/g-C_(3)N_(4) Photocatalytic Material

高效、稳定光催化材料的开发是光催化技术应用的关键,以尿素、硝酸铋和溴化钾等为原料,通过一步水热法制备了BiOBr/g-C_(3)N_(4)(Bix/CN)光催化剂,结合紫外-可见吸收光谱结果计算出BiOBr和g-C_(3)N_(4)的导带位置在0.52和-1.1 eV,价带位置在3.38和1.55 eV处,光电催化及荧光测试中Bix/CN表现出较高的光电流和较低的电荷转移电阻,说明复合可有效降低光催化材料中电子-空穴的复合率,其中Bi3/CN在可见光辐射10 min下,对水溶液中罗丹明B的总去除率可达到81.35%,循环使用5次后对RhB的总去除率仅下降了6%。复合材料光催化效率的提高主要依赖于2种二维单体的有效耦合,光电催化和自由基捕获试验结果表明,g-C_(3)N_(4)导带上活性物种·O_(2)^(-)的有效生成是复合材料光催化性能提高的本质原因。

The development of efficient and stable photocatalytic materials is the key to the application of photocatalytic technology.In this paper,urea,bismuth nitrate and potassium bromide were used as raw materials,BiOBr/g-C_(3)N_(4) composite photocatalysts(Bix/CN)with different mass ratios were prepared by one-step hydrothermal method.Based on the results of UV-Vis,the calculated ECB values of BiOBr and g-C_(3)N_(4) are 0.52 eV and-1.1 eV,respectively,while the calculated EVB values of BiOBr and g-C_(3)N_(4) are 3.38 eV and 1.55 eV,respectively.Photoelectric catalytic performance tests show that Bi3/CN has the higher photocurrent density and lower charge transfer resistance.When the visible light irradiation time is 10 min,the total removal rate of RhB by Bi3/CN is 81.35%.The total removal rate of RhB by Bi3/CN decreases by only 6%after reused for 5 cycles,indicating that Bi3/CN has high and stable photocatalytic efficiency for RhB.The improvement of photocatalytic efficiency of composite photocatalyst mainly depends on the effective coupling of the two-dimensional monomers,and the effective interface contact improves the photogenerated electron transfer and carrier separation efficiency.The photocatalytic enhancement mechanism is proposed as that the accumulated electrons on CB of g-C_(3)N_(4) for generation of•O_(2)^(-)are the essential reason for the improvement of photocatalytic performance.