Ma Jianchao, Yang Shurong, Shi Huixian, Pang Jin, Zhang Xiaopeng, Wang Yuxing, Sun Hongqi
College of Mining Engineering, Taiyuan University of Technology Taiyuan 030024 Shanxi P. R. China.
Institute of New Carbon Materials, Taiyuan University of Technology Taiyuan 030024 Shanxi P. R. China
RSC Adv. 2020 Apr 22;10(27):16027-16037. doi: 10.1039/d0ra02455d. eCollection 2020 Apr 21.
Efficient visible-light-driven heterojunction photocatalysts have attracted broad interest owing to their promising adsorption and degradation performances in the removal of organic pollutants. In this study, a mesoporous exfoliated bentonite (EB)/AgPO/AgBr (30%) photocatalyst was obtained by stripping and exfoliating bentonite as the support for loading AgPO and AgBr. The particle size ranges of AgPO and AgBr were about 10-30 nm and 5-10 nm, respectively. The exfoliated bentonite could greatly improve the dispersion and adsorption of AgPO and AgBr, and significantly enhance the stability of the material during paraben photodegradation. 0.2 g L methylparaben (MPB) was completely decomposed over the EB/AgPO/AgBr (30%) in 40 min under visible light irradiation. In addition, the photocatalytic activity of EB/AgPO/AgBr (30%) remained at about 91% after five recycling runs manifesting that EB/AgPO/AgBr (30%) possessed excellent stability. Radical quenching tests revealed that holes (h) and hydroxyl radicals (·OH) were the major radicals. They attacked the side chain on the benzene ring of parabens, which were gradually oxidized to the intermediates, such as benzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, azelaic acid, and eventually became CO and HO. The enhancement of photocatalytic activity and photo-stability could be ascribed to the stable structural characteristics, enlarged surface area, high absorption ability, and improved light absorption ability from loading AgPO onto EB. Meanwhile, the matched energy levels of AgPO and AgBr made the photoelectron-hole pairs separate and transfer effectively at the interfaces. As a result, the photocatalytic properties of EB/AgPO/AgBr (30%) composites were enhanced.
高效的可见光驱动异质结光催化剂因其在去除有机污染物方面具有良好的吸附和降解性能而引起了广泛关注。在本研究中，通过剥离和剥落膨润土作为负载AgPO和AgBr的载体，获得了介孔剥离膨润土（EB）/AgPO/AgBr（30%）光催化剂。AgPO和AgBr的粒径范围分别约为10-30nm和5-10nm。剥落的膨润土可以极大地改善AgPO和AgBr的分散和吸附，并在对羟基苯甲酸光降解过程中显著提高材料的稳定性。在可见光照射下，0.2gL对羟基苯甲酸（MPB）在EB/AgPO/AgBr（30%）上40分钟内完全分解。此外，EB/AgPO/AgBr（30%）在五次循环运行后光催化活性保持在约91%，表明EB/AgPO/AgBr（30%）具有优异的稳定性。自由基猝灭试验表明，空穴（h）和羟基自由基（·OH）是主要的自由基。它们攻击对羟基苯甲酸苯环上的侧链，侧链逐渐被氧化为苯甲酸、3-羟基苯甲酸、4-羟基苯甲酸、壬二酸等中间体，最终变成CO₂和H₂O。光催化活性和光稳定性的提高可归因于稳定的结构特征、增大的表面积、高吸收能力以及将AgPO负载到EB上后提高的光吸收能力。同时，AgPO和AgBr匹配的能级使光生电子-空穴对在界面处有效分离和转移。结果，EB/AgPO/AgBr（30%）复合材料的光催化性能得到增强。
