窄带隙半导体耦合Bi_2S_3/g-C_3N_4催化剂制备及光催化性能

Preparation of Bi_2S_3/g-C_3N_4 photocatalysts by coupling with narrow-band-gap semiconductor and the photocatalytic activities

利用原位生成法,制备了Bi_2S_3含量可调的Bi_2S_3/g-C_3N_4复合材料。通过X-射线衍射(XRD)、透射电镜(TEM)、光致发光光谱(PL)、时间分辨荧光衰减光谱等手段对制备的光催化剂物相、形貌、结构和性能进行表征分析。可见光照射下,以罗丹明B(Rh B)为降解模型评价Bi_2S_3/g-C_3N_4复合材料的催化性能。结果表明:Bi_2S_3沉积在g-C_3N_4表面,显著增强g-C_3N_4的可见光催化性能,并随着Bi_2S_3含量不同,复合光催化剂Bi_2S_3/g-C_3N_4的催化性能发生变化,其中Bi_2S_3质量分数为5%时表现出最佳的可见光催化活性。利用捕获剂、NBT转化确定h+是主要的活性物种,O_2^-·是次要活性物种。对Bi_2S_3/g-C_3N_4光催化活性增强机理进行研究,Bi_2S_3的加入显著增强g-C_3N_4对可见光的吸收,并与g-C_3N_4之间形成异质结,促进光生电子空穴的有效分离,延长载流子寿命,显著增强g-C_3N_4光催化性能。

The Bi2S3/g-C3N4 composite photocatalysts with different Bi2S3 contents were prepared by in-situ synthesis method. The phase, morphology, structure and optical property of as-obtained photoeatalysts were studied by X-ray diffraction （ XRD）, transmissionelectron microscopy （ TEM）, photolumineseenee （PL） spectroscopy measurements and time-resolved fluorescence decay spectra. Rhodamine B （ RhB ） was selected as pollutant models to evaluate the visible-light photoeatalytie activity of Bi2S3/g-C3 N4 composite photoeatalysts. As a result, the visible-light photoeatalytic activity of g-C3N4 was greatly improved by decorating the Bi2S3 on surface. Besides, the photocatalytic activity of BizS3/g-C3N4 composite photocatalysts was obviously influenced with the adding amount of Bi2S3, and the optimal amount of Bi2S3 was determined to be 5%. The roles of reactive species during photocatalysis were verified by a series of combined techniques, including the active species trapping experiments and NBT transformation over Bi2S3/g-CaN4 composites. The results suggested that h ~ played the major role and ~ 02 was the secondary active species. Furthermore, the mechanism for photoeatalytic activity enhancement of Bi2Sa/g-C3N4 composite photocatalysts was also revealed. It may be ascribed to the increasing visible-light absorption and the formation of heterostructures at the Bi2S3/g-C3N4 interface, which can facilitate the separation of photogenerated electrons and holes and extend the carrier lifetime.