GO/TiO2-g-C3N4纳米复合材料的制备及可见光催化性能

以水热法制备的20% g-C₃N₄/TiO₂（20%为质量分数）为基，将其与不同质量分数的氧化石墨烯（GO）复合制备出可见光催化性能优良的GO/TiO₂-g-C₃N₄三元复合材料。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-Vis DRS）、光致荧光光谱（PL）、瞬态光电流响应等分析测试手段对样品的结构、形貌和光电性能进行表征。研究了不同质量分数GO的加入对GO/TiO₂-g-C₃N₄在可见光下降解亚甲基蓝（MB）溶液的影响。结果表明： g-C₃N₄/TiO₂与GO复合后，锐钛矿相TiO₂颗粒形成小团簇附着在g-C₃N₄和GO片层表面，且当GO含量为15%时，TiO₂形成的团簇最小，对可见光的吸收最多且光生电子-空穴对的复合率最低。可见光照射下，15% GO/TiO₂-g-C₃N₄复合材料对MB的降解率在3 h内可达98.4%，且其降解速率常数（0.022 4 min^-1）分别是纯TiO₂（0.001 5 min^-1）和g-C₃N₄/TiO₂（0.002 5 min^-1）的15倍和9倍。

Preparation and Photocatalytic Properties of GO/TiO2-g-C3N4 Nanocomposites

GO/TiO₂-g-C₃N₄ ternary composites having good visible light catalytic performances, which was based on the prepared 20%g-C₃N₄/TiO₂ composites (the mass fraction of g-C₃N₄ was 20%) by hydrothermal process, were successfully synthesized by mixing graphene oxide (GO) dispersions with different mass fractions. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), and transient photocurrent analytical tests are used to characterize and analyze the crystal structures, morphologies and optical properties of g-C₃N₄/ TiO₂-based photocatalysts. The effect of TiO₂-g-C₃N₄ compounded with different GO mass fractions on the degradation of methylene blue (MB) solution under visible light was studied. The results show that with the optimized amount of GO of 15%, the smallest anatase phase TiO₂ particles attached to the surface of g-C₃N₄ and GO sheets was found to be the enhancing photocatalytic efficiency, which can be attributed to higher light absorption and lower photoelectron-hole recombination rate in comparison with g-C₃N₄/TiO₂ binary composites or pure TiO₂. The degradation rate of MB by 15%GO/TiO₂-g-C₃N₄ composite could reach 98.4% within three hours, and its degradation rate constant (0.022 4 min^-1) was about 15 times and 9 times higher than those of pure TiO₂ (0.001 5 min^-1) and g-C₃N₄/ TiO₂ (0.002 5 min^-1), respectively.