Lin Zehao, Yu Bo, Huang Jianguo
Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China.
Langmuir. 2020 Jun 2;36(21):5967-5978. doi: 10.1021/acs.langmuir.0c00847. Epub 2020 May 18.
A novel cellulose-derived hierarchical g-CN/TiO-nanotube heterostructured nanocomposite was fabricated by in situ coating thin g-CN layers onto the surfaces of the TiO nanotubes, which were synthesized by utilizing the natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. These g-CN/TiO-nanotube composites with varied thicknesses (ca. 3-30 nm) of the outer g-CN layers displayed improved visible-light (λ > 420 nm)-driven photocatalytic degradation performances toward methylene blue. The optimal nanocomposite with an outer g-CN layer of ca. 7.5 nm composed of 46 wt % g-CN displayed an apparent rate constant of 0.0035 min, which was 8.5- and 4-fold larger than those of the referential TiO-nanotube and g-CN powder. The excellent and durable photocatalytic activities of these cellulose-derived g-CN/TiO-nanotube composites were ascribed to their hierarchically network porous structures replicated from the cellulose template, as well as the formation of close heterojunctions in-between the g-CN and TiO phases. Moreover, it was demonstrated that the photocatalytic mechanism matched with the type-II heterostructured model, while the main effective species during the photocatalytic processes of the nanocomposite were proved to be superoxide radicals.
通过利用天然纤维素物质（如商用普通滤纸）作为结构模板合成二氧化钛纳米管，并在其表面原位包覆薄的石墨相氮化碳（g-CN）层，制备了一种新型的纤维素衍生的分级g-CN/TiO纳米管异质结构纳米复合材料。这些具有不同厚度（约3-30nm）外层g-CN层的g-CN/TiO纳米管复合材料对亚甲基蓝表现出改善的可见光（λ>420nm）驱动的光催化降解性能。具有约7.5nm外层g-CN层且由46wt%g-CN组成的最佳纳米复合材料表现出0.0035min的表观速率常数，分别是参考TiO纳米管和g-CN粉末的8.5倍和4倍。这些纤维素衍生的g-CN/TiO纳米管复合材料优异且持久的光催化活性归因于从纤维素模板复制而来的分级网络多孔结构，以及g-CN和TiO相之间紧密异质结的形成。此外，证明了光催化机理符合II型异质结构模型，同时纳米复合材料光催化过程中的主要有效物种被证明是超氧自由基。
