SiO2/g-C3N4复合粉体制备及其光催化性能

以Stöber法制备出的二氧化硅(SiO₂)微球和三聚氰胺为原料,两者按一定质量比混合后得到前驱体,通过煅烧该前驱体可成功获得SiO₂/g-C₃N₄复合粉体。利用XRD、SEM、UV-Vis和BET等表征手段对获得的复合粉体进行物相组成、形貌、可见光吸收性能以及比表面积大小等进行分析和测试。结果表明,改进的Stöber法制备出的球形SiO₂平均粒径约为200 nm,具有良好的分散性。SiO₂/g-C₃N₄复合粉体中SiO₂含量约为75%(质量分数)时,其比表面积最大,约为23.7 m²/g。同时,以罗丹明B和亚甲基蓝为目标污染物,在可见光照射下,探究了不同g-C₃N₄负载量SiO₂/g-C₃N₄复合粉体的光催化性能。结果表明,随着复合粉体中g-C₃N₄含量的降低,复合粉体的可见光催化活性反而逐渐升高,g-C₃N₄含量约为25%(质量分数)时复合粉体光催化降解罗丹明B和亚甲基蓝效果最好。原因可归结为,复合粉体的强吸附增强了可见光催化性能。

Synthesis and Photocatalytic Properties of SiO2/g-C3N4 Composite Powders

SiO₂/g-C₃N₄ composite powders were successfully prepared by calcination of proper as-prepared silicon dioxide (SiO₂) and melamine (C₃H₆N₆) composite precursors. The phase composition, morphology,optical absorption performance, and specific surface area of the composite powders were carried out by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), ultraviolet-visible light absorption spectrum (UV-Vis) andBET method. Results show that the average particle size of spherical SiO₂ prepared by modified Stöber method is about 200 nm and it has good dispersibility. When the content of SiO₂ is about 75% (mass fraction) in SiO₂/g-C₃N₄ composite powder, the specific surface area of composite powder is the largest, about 23.7 m²/g. At the same time, the photocatalytic properties of SiO₂/g-C₃N₄ composite powders with different g-C₃N₄ loading content were investigated under visible light irradiation with Rhodamine B and methylene blue as the target pollutants. Results indicate that with the decrease of the content of g-C₃N₄ in the composite powders, the visible light activity of the composite powder increases gradually. The composite powder with about 25% (mass fraction) g-C₃N₄ has the best photocatalytic degradation effect on Rhodamine B and methylene blue. The reason is that the strong absorption of composite powders enhances the visible light photocatalytic property.