Nano-Porous TiO_2 Photoanode for Higher Electrolyte Accessibility Using Micro-fibrillated Cellulose as a Sacrificial Template

摘要

A novel method of fabricating a nano-channeled porous titania photoanode was developed by using micro-fibrillated cellulose as a template for formation of a sol-gel TiO_2 precursor to enhance electrolyte penetration. The cellulose was homogenized and consists of microfibers with a 30 nm-diameter and several microns in length uniformly suspended in either water or isopropanol, depending on the fabricating method. In the non-aqueous environment, hydrolysis and condensation rates were greatly reduced and an ultra thin film around 500nm was prepared on glass substrate. In the aqueous solution, a 3-5um thick film was made by liquid phase deposition and doctor-blade. Cellulose was removed by calcination resulting in the formation of the porous, channeled structure. Scanning electron microscopic images of focused ion beam sections confirm the ordered porous, channeled structure. Analysis with Raman spectroscopy, X-ray diffraction, and UV-Vis spectroscopy, verify the anatase phase and the surface properties of the photoanode.