Semwal Anubhi, Sajwan Devanshu, Rawat Jyoti, Gambhir Lokesh, Sharma Himani, Dwivedi Charu
Department of Chemistry, Doon University, Dehradun, 248001, Uttarakhand, India.
Department of Biotechnology, School of Basic & Applied Sciences, Shri Guru Ram Rai University, Dehradun, 248001, India.
Environ Sci Pollut Res Int. 2023 Apr;30(16):45827-45839. doi: 10.1007/s11356-023-25336-7. Epub 2023 Jan 28.
Zinc imidazolate framework (ZIF-8) and titanium dioxide (TiO) have been extensively studied as photocatalysts and have shown remarkable potential. In this study, we report the synthesis of a type II heterojunction photocatalyst based on carbon-doped TiO (C-TiO) and ZIF-8 as a potentially improved material for solar light-harvested methylene blue (MB) degradation. Pure ZIF-8 has a wide band gap of 4.9 eV, due to which the application of this material to visible light-assisted photocatalytic performance is a challenging task. Therefore, C-TiO has been chosen as a composite material with ZIF-8 owing to its narrow band gap compared to TiO. This enables the free radical-initiated photocatalytic reaction to shift into the visible region instead of the ultraviolet region. To construct the C-TiO/ZIF-8 heterostructure, the zinc-based ZIF matrix has been built upon the exterior of C-TiO nanoparticles. UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) corroborated the decrease in the band gap of ZIF-8 after the fabrication of C-TiO/ZIF-8, while X-ray diffraction (XRD) analysis demonstrated a decrease in average d-spacing and average crystallite size of the synthesized photocatalyst. Raman spectra and X-ray photoelectron spectroscopy (XPS) analysis of the synthesized samples were also performed to further understand their chemical structure and elemental content. Ultraviolet photoelectron spectroscopy (UPS) and high-resolution transmission electron microscopy (HRTEM) analyses were performed to understand the valence band (VB) states and the morphology of C-TiO/ZIF-8. The comparison between pure ZIF-8 and C-TiO/ZIF-8 in the photocatalytic degradation of MB under visible light has also been drawn. A possible charge-transfer mechanism for the same has also been proposed. It is concluded that the synergistic effect of C-TiO and ZIF-8 in C-TiO/ZIF-8 produces an effective material for photocatalytic dye degradation.
咪唑锌框架（ZIF-8）和二氧化钛（TiO₂）作为光催化剂已被广泛研究，并显示出显著的潜力。在本研究中，我们报道了基于碳掺杂TiO₂（C-TiO₂）和ZIF-8合成的II型异质结光催化剂，作为一种潜在的改进材料用于太阳光捕获降解亚甲基蓝（MB）。纯ZIF-8具有4.9 eV的宽带隙，因此将这种材料应用于可见光辅助光催化性能是一项具有挑战性的任务。因此，由于C-TiO₂与TiO₂相比具有较窄的带隙，所以选择C-TiO₂作为与ZIF-8的复合材料。这使得自由基引发的光催化反应能够转移到可见光区域而不是紫外区域。为了构建C-TiO₂/ZIF-8异质结构，在C-TiO₂纳米颗粒的外部构建了锌基ZIF基质。紫外可见漫反射光谱（UV-Vis-DRS）证实了制备C-TiO₂/ZIF-8后ZIF-8带隙的减小，而X射线衍射（XRD）分析表明合成的光催化剂的平均d间距和平均微晶尺寸减小。还对合成样品进行了拉曼光谱和X射线光电子能谱（XPS）分析，以进一步了解它们的化学结构和元素含量。进行了紫外光电子能谱（UPS）和高分辨率透射电子显微镜（HRTEM）分析，以了解C-TiO₂/ZIF-8的价带（VB）状态和形态。还比较了纯ZIF-8和C-TiO₂/ZIF-8在可见光下对MB的光催化降解情况。并提出了一种可能的电荷转移机制。得出的结论是，C-TiO₂/ZIF-8中C-TiO₂和ZIF-8的协同效应产生了一种用于光催化染料降解的有效材料。
