ML-WO3/TiO2异质结的制备及其对罗丹明B的光催化降解

采用空间限域法制备了单层三氧化钨纳米片(ML-WO₃),然后将其与TiO₂复合得到ML-WO₃/TiO₂纳米材料,被用来在模拟太阳光下对罗丹明B进行光催化降解。ML-WO₃/TiO₂的组成和光学特性通过扫描电镜、透射电镜、高分辨透射电镜、X射线衍射、紫外-可见吸收光谱和光致发光光谱手段进行表征。结果证实,纳米ML-WO₃/TiO₂克服了纯TiO₂带隙较大的缺陷,在全波段太阳光表现出比ML-WO₃和TiO₂更强的吸收性能,ML-WO₃与TiO₂之间具有明显的协同效应。活性物种捕获实验表明.OH和.O_2^-自由基是RhB降解的主要活性物种。ML-WO₃和TiO₂之间构建的Z型异质结电荷转移路径能够保证光生载流子的高效分离和重组。在5次循环实验后ML-WO₃/TiO₂的光催化活性仍能接近80%,具有良好的光化学稳定性。通过高效液相色谱-质谱检测RhB的中间产物,推测了RhB可能的降解路径。

Preparation of ML-WO3/TiO2 heterojunction and its photocatalytic degradation of rhodamine B

Monolayer tungsten trioxide nanosheets (ML-WO₃) were prepared via the space-confined strategy and then compounded with TiO₂ to obtain ML-WO₃/TiO₂ nanomaterials, which were used for the photocatalytic degradation of rhodamine B under simulated solar light. The compositional structure and optical features of ML-WO₃/TiO₂ were characterized by means of SEM, TEM, HRTEM, XRD, UV-Vis and PL. The results showed that the ML-WO₃/TiO₂ overcame the defect of large band gap of pure TiO₂ and exhibited stronger absorption performance than ML-WO₃ and TiO₂ in the full wavelength solar light, and there was a remarkable synergistic relationship between ML-WO₃ and TiO₂. The active species capture experiments showed that .OH and .O_2^- free radicals were the main active species for RhB degradation. The Z-scheme heterojunction charge transfer pathway constructed between ML-WO₃ and TiO₂ can ensure efficient separation and recombination of photogenerated carriers. The photocatalytic activity of the ML-WO₃/TiO₂ composites could still approach 80% after 5 cycles of experiments, with good photochemical stability. The possible degradation pathway of RhB was speculated by the detection of RhB intermediates by HPLC-MS.