Free-standing carbon nanotube–titania photoactive sheets

Abstract

We report on the development of a new photoactive material via titania (TiO2) nanoparticle deposition on free-standing aligned carbon nanotube (CNT) sheets. Controlling homogeneous dispersion of negatively charged TiO2 nanoparticles, achieved by adjusting pH higher than the point of zero charge (PZC), influenced electrochemical deposition of TiO2 on CNT sheets substrate. Varying deposition time with constant voltage, 5V allowed different thickness of TiO2 to be deposited layer on the CNT sheets. The thickness and morphology of CNT–TiO2 sheets was verified by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Electrochemical experiments show that diffusion coefficient of Fe(CN)63- was 5.56×10−6cm2s−1 at pristine CNT sheets and 2.19×10−6cm2s−1 at the CNT–TiO2 sheets. Photocatalytic activity for CNT–TiO2 sheets exhibits high photocurrent density (when deposition time=30min, 4.3μAcm−2 in N2, 13.4μAcm−2 in CO2). This paper proved a possibility to use CNT–TiO2 sheets based on highly-aligned CNT sheets substrate as new photoactive material.