Madima Ntakadzeni, Kefeni Kebede K, Mishra Shivani B, Mishra Ajay K
Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, Florida, Roodepoort, Johannesburg, 1709, South Africa.
College of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, China.
Heliyon. 2022 Sep 18;8(9):e10683. doi: 10.1016/j.heliyon.2022.e10683. eCollection 2022 Sep.
In the current study, a direct S-scheme titanium dioxide/graphitic carbon nitride (TiO/g-CN) heterojunction structure was fabricated via simultaneous calcination of TiO precursors and g-CN. leaf extract was utilized as a reductant for TiO production through a green synthetic method, and g-CN was prepared by thermal decomposition of melamine. The pristine and nanocomposite photocatalysts were characterized by XRD, FTIR, BET, TGA, HRTEM, UV-vis DRS, and PL to elucidate their physicochemical properties. The photocatalytic activity of synthesized photocatalysts was examined through the degradation of rhodamine B (RhB) and methylene blue (MB) dyes under simulated solar light irradiation. The nanocomposite exhibited commendable photocatalytic performances with 96% degradation efficiency of RhB attained in 120 min and 95% degradation efficiency of MB achieved in 150 min. The enhanced photocatalytic activities were attributable to visible light-harvesting characteristics and the formation of an S-scheme heterojunction system between two catalysts which promotes interfacial charge separation efficiency and longer charge carrier lifespan. After 4 consecutive cycles, the degradation efficiencies of both RhB and MB remained above 85%. According to the trapping experiments, OH and O radicals were critical in the degradation of RhB, while h and O radicals were dominant in the degradation of MB. The nanocomposite was also tested for elution of actual water pollutants by combining two dyes, and above 90% degradation efficiencies were achieved for both dyes after 240 min.
在当前研究中，通过同时煅烧TiO前驱体和g-CN制备了一种直接的S型二氧化钛/石墨相氮化碳（TiO₂/g-C₃N₄）异质结结构。利用叶提取物通过绿色合成方法作为TiO₂制备的还原剂，通过三聚氰胺的热分解制备g-C₃N₄。通过XRD、FTIR、BET、TGA、HRTEM、UV-vis DRS和PL对原始光催化剂和纳米复合光催化剂进行了表征，以阐明它们的物理化学性质。通过在模拟太阳光照射下降解罗丹明B（RhB）和亚甲基蓝（MB）染料来考察合成光催化剂的光催化活性。该纳米复合材料表现出优异的光催化性能，在120分钟内RhB的降解效率达到96%，在150分钟内MB的降解效率达到95%。增强的光催化活性归因于可见光捕获特性以及两种催化剂之间形成的S型异质结体系，该体系促进了界面电荷分离效率和更长的电荷载流子寿命。经过4个连续循环后，RhB和MB的降解效率均保持在85%以上。根据捕获实验，·OH和O₂·自由基在RhB的降解中起关键作用，而h⁺和O₂·自由基在MB的降解中占主导地位。还通过组合两种染料对该纳米复合材料进行了实际水污染物洗脱测试，240分钟后两种染料的降解效率均达到90%以上。
