Hierarchical, titania-coated, carbon nanofibrous material derived from a natural cellulosic substance

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.