CNT-TiO2−δ Composites for Improved Co-Catalyst Dispersion and Stabilized Photocatalytic Hydrogen Production

• Main Authors: Peirong Chen, Lidong Wang, Ping Wang, Aleksander Kostka, Michael Wark, Martin Muhler, Radim Beranek
• Format: Article
• Language: English
• Published: MDPI AG 2015-03-01
• Series: Catalysts
• Subjects: carbon nanotubes; TiO2; oxygen deficiency; photocatalytic hydrogen production; platinum co-catalyst; stability
• Online Access: http://www.mdpi.com/2073-4344/5/1/270

Composites consisting of carbon nanotubes (CNTs) grown directly on oxygen-deficient anatase TiO2 (TiO2−δ) were synthesized by a two-step chemical vapor deposition (CVD) method and applied in photocatalytic hydrogen production from aqueous methanol solutions using photodeposited Pt as the co-catalyst. Thermogravimetry coupled with mass spectroscopy, X-ray diffraction, scanning electron microscopy, photocurrent analysis, X-ray photoelectron spectroscopy, and (scanning) transmission electron microscopy were performed to investigate the physical and (photo)chemical properties of the synthesized CNT-TiO2−δ composites before and after photocatalytic methanol reforming. The initial photocatalytic activity of TiO2 was found to be significantly improved in the presence of oxygen vacancies. An optimized amount (~7.2 wt%) of CNTs grown on the TiO2−δ surface led to a highly effective stabilization of the photocatalytic performance of TiO2−δ, which is attributed to the improved dispersion and stability of the photodeposited Pt co-catalyst nanoparticles and enhanced separation efficiency of photogenerated electron-hole pairs, rendering the photocatalysts less prone to deactivation.