Free-standing carbon nanotube-titania photoactive sheets

Youngmi Koo; Rachit Malik; Noe Alvarez; Vesselin N Shanov; Mark Schulz; Jag Sankar; Yeoheung Yun

doi:10.1016/j.jcis.2015.02.022

Free-standing carbon nanotube-titania photoactive sheets

J Colloid Interface Sci. 2015 Jun 15:448:148-55. doi: 10.1016/j.jcis.2015.02.022. Epub 2015 Feb 14.

Authors

Youngmi Koo¹, Rachit Malik², Noe Alvarez², Vesselin N Shanov², Mark Schulz², Jag Sankar¹, Yeoheung Yun³

Affiliations

¹ Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A&T State University, Greensboro, NC 27411, USA.
² Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221, USA.
³ Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A&T State University, Greensboro, NC 27411, USA. Electronic address: yyun@ncat.edu.

PMID: 25725399
DOI: 10.1016/j.jcis.2015.02.022

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, 5 V 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)6(3-) was 5.56×10(-6) cm(2) s(-1) at pristine CNT sheets and 2.19×10(-6) cm(2) s(-1) at the CNT-TiO2 sheets. Photocatalytic activity for CNT-TiO2 sheets exhibits high photocurrent density (when deposition time=30 min, 4.3 μA cm(-2) in N2, 13.4 μA cm(-2) in CO2). This paper proved a possibility to use CNT-TiO2 sheets based on highly-aligned CNT sheets substrate as new photoactive material.

Keywords: A. Carbon nanotube sheets; B. Titanium oxide; C. Electrochemical deposition; D. Carbon support; E. Electrocatalysis.