Ma Zilun, Shi Liyan, Qu Wenwen, Hu Qiong, Chen Ruifang, Wang Yijun, Chen Zhen
Faculty of Science, Kunming University of Science and Technology Kunming 650500 China
Key Laboratory of Unconventional Metallurgy Education Ministry, Kunming University of Science and Technology Kunming 650093 China.
RSC Adv. 2020 Dec 9;10(71):43447-43458. doi: 10.1039/d0ra08597a. eCollection 2020 Nov 27.
Semiconductor-based heterojunction photocatalysts with a special active crystal surface act as an essential part in environmental remediation and renewable energy technologies. In this study, an RGO/CdS/TiO step-scheme with high energy {001} TiO facets was successfully fabricated a microwave-assisted solvothermal method. The photocatalytic performance of as-prepared samples was assessed by degrading methylene blue under visible light irradiation. We found that the photocatalytic activity of the RGO/CdS/TiO step-scheme heterojunction was related to the proportion of TiO. A ternary sample with a TiO content of 10 wt% exhibited superior photocatalytic performance, and approximately 99.7% of methylene blue was degraded during 50 min of visible illumination which was much higher than the percentages found for TiO, CdS, RGO/TiO, and RGO/CdS. The greatly improved photocatalytic performance is due to the exposure of the reactive {001} surface of TiO and the formation of a CdS/TiO heterojunction step-scheme, which effectively inhibits the recombination of charge carriers at the heterogeneous interfaces. Moreover, the incorporation of graphene further enhances the visible light harvesting and serves as an electron transport channel for rapidly separating photogenerated carriers. Based on the PL, XPS, photoelectrochemical properties and the free radical capturing experiment results, a possible photodegradation mechanism was proposed.
具有特殊活性晶体表面的半导体基异质结光催化剂在环境修复和可再生能源技术中起着至关重要的作用。在本研究中，通过微波辅助溶剂热法成功制备了具有高能{001} TiO晶面的RGO/CdS/TiO阶梯型异质结。通过在可见光照射下降解亚甲基蓝来评估所制备样品的光催化性能。我们发现RGO/CdS/TiO阶梯型异质结的光催化活性与TiO的比例有关。TiO含量为10 wt%的三元样品表现出优异的光催化性能，在50分钟的可见光照射下，约99.7%的亚甲基蓝被降解，这远高于TiO、CdS、RGO/TiO和RGO/CdS的降解率。光催化性能的大幅提高归因于TiO活性{001}表面的暴露以及CdS/TiO异质结阶梯型的形成，这有效地抑制了异质界面处电荷载流子的复合。此外，石墨烯的掺入进一步增强了可见光的捕获，并作为电子传输通道快速分离光生载流子。基于PL、XPS、光电化学性质和自由基捕获实验结果，提出了一种可能的光降解机理。
