Biogenic Hierarchical TiO2/SiO2 Derived from Rice Husk and Enhanced Photocatalytic Properties for Dye Degradation

BackgroundRice husk, an agricultural bioresource, is utilized as a non-metallic bio-precursor to synthesize biogenic hierarchical TiO2/SiO2 (BH-TiO2/SiO2) and the products are applied to dye degradation. Methodology/Principal FindingsThe as-prepared BH-TiO2/SiO2 samples are characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), nitrogen-adsorption measurement, UV-vis spectroscopy and electronic paramagnetic resonance (EPR). The results show that BH-TiO2/SiO2 possesses both anatase and rutile phases with amorphous SiO2 as background, which contains mesopore structure, and nitrogen derived from original rice husk is self-doped into the lattice. Besides, the light-harvesting within the visible-light range of BH-TiO2/SiO2 has been enhanced. Moreover, the catalytic activity of BH-TiO2/SiO2 has been proven by EPR, and both the photocatalytic activity and stability of BH-TiO2/SiO2 are improved as well, which has been illustrated by cycled degradation of methylene blue dye under irradiation. Conclusions/SignificanceThis work provides a good way to combine natural hierarchical porous structure with synthetic material chemistry based on available biomass in the vast natural environment for the sustainable development of human society, and extends potentials of biomass in applications such as photocatalysts, sunlight splitting water and so forth.研究背景 稻壳作为一种农业生物资源，被用作非金属生物前驱体，用于合成生物源性分级结构TiO₂/SiO₂（BH-TiO₂/SiO₂），所得产物应用于染料降解。 研究方法与主要结果 采用X射线衍射（X-ray diffraction，XRD）、X射线光电子能谱（X-ray photoelectron spectroscopy，XPS）、氮气吸附测试、紫外-可见光谱以及电子顺磁共振（electronic paramagnetic resonance，EPR）对所制备的BH-TiO₂/SiO₂样品进行表征。结果表明，BH-TiO₂/SiO₂同时具备锐钛矿相与金红石相，以无定形SiO₂为基底，且具有介孔结构；源自原始稻壳的氮元素被自掺杂至晶格之中。此外，BH-TiO₂/SiO₂的可见光范围内光捕获能力得到提升。电子顺磁共振（EPR）表征证实了该材料的催化活性；同时通过光照下亚甲基蓝染料的循环降解实验，证明BH-TiO₂/SiO₂的光催化活性与稳定性均得到改善。 研究意义 本研究为结合天然分级多孔结构与合成材料化学提供了可行路径，以自然界中广泛分布的可再生生物质为原料，助力人类社会可持续发展；同时拓展了生物质在光催化剂、太阳光解水等领域的应用潜力。