Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China.
Chemistry. 2010 Jul 12;16(26):7730-40. doi: 10.1002/chem.201000436.
Hierarchical, titania-coated, nanofibrous, carbon hybrid materials were fabricated by employing natural cellulosic substances (commercial filter paper) as a scaffold and carbon precursor. Ultrathin titania films were firstly deposited by means of a surface sol-gel process to coat each nanofiber in the filter paper, and successive calcination treatment under nitrogen atmosphere yielded the titania-carbon composite possessing the hierarchical morphologies and structures of the initial paper. The ultrathin titania coating hindered the coalescence effect of the carbon species that formed during the carbonization process of cellulose, and the original cellulose nanofibers were converted into porous carbon nanofibers (diameters from tens to hundreds of nanometers, with 3-6 nm pores) that were coated with uniform anatase titania thin films (thickness approximately 12 nm, composed of anatase nanocrystals with sizes of approximately 4.5 nm). This titania-coated, nanofibrous, carbon material possesses a specific surface area of 404 m(2) g(-1), which is two orders of magnitude higher than the titania-cellulose hybrid prepared by atomic layer deposition of titania on the cellulose fibers of filter paper. The photocatalytic activity of the titania-carbon composite was evaluated by the improved photodegradation efficiency of different dyes in aqueous solutions under high-pressure, fluorescent mercury-lamp irradiation, as well as the effective photoreduction performance of silver cations to silver nanoparticles with ultraviolet irradiation.
采用天然纤维素物质（商用滤纸）作为支架和碳前体，制备了具有分层结构的、涂覆有二氧化钛的、纳米纤维状、碳杂化材料。首先通过表面溶胶-凝胶法在滤纸中的每根纳米纤维上沉积超薄的二氧化钛薄膜，然后在氮气气氛下进行连续煅烧处理，得到具有初始纸分层形貌和结构的二氧化钛-碳复合材料。超薄的二氧化钛涂层阻碍了纤维素碳化过程中形成的碳物种的聚集效应，原始的纤维素纳米纤维转化为多孔碳纳米纤维（直径从几十到几百纳米，具有 3-6nm 的孔），这些碳纳米纤维涂覆有均匀的锐钛矿型二氧化钛薄膜（厚度约为 12nm，由约 4.5nm 大小的锐钛矿纳米晶组成）。这种涂覆有二氧化钛的、纳米纤维状的、碳材料的比表面积为 404m(2)g(-1)，比原子层沉积在滤纸纤维上的二氧化钛-纤维素杂化材料高两个数量级。在高压、荧光汞灯照射下，通过不同染料在水溶液中的光降解效率的提高，以及在紫外光照射下银阳离子到银纳米颗粒的有效光还原性能，评估了二氧化钛-碳复合材料的光催化活性。
