To address the ongoing concerns about the global energy supply, scientists are trying to develop sustainable and renewable energy platforms. This includes the photocatalytic generation of hydrogen gas for use as a renewable energy source. In this process, solar light is applied to photochemically split water to generate hydrogen. Titania is commonly used as a semiconductor in such photoelectrochemical processes as the photoanode but the material still requires improvements for the electron transfer and kinetic profiles of optimal H2 generation.
Patrick Schmuki, University of Erlangen-Nuremberg, Germany, and King Abdulaziz University, Jeddah, Saudi Arabia, and colleagues have investigated three approaches to titania “blackening” and the resulting influence on noble-metal-free H2 generation. These three treatments are i) the previously reported high-pressure hydrogenation of TiO2 , ii) a high temperature reduction in argon, and iii) an electrochemical (cathodic) reduction. The “black” TiO2 nanotubes produced were tested for their electrochemical behavior and electrical conductivity.
Simply reducing TiO2 leads to beneficial properties for use in dye-sensitized solar cells, lithium batteries, and photoelectrochemical processes. An interesting synergistic effect of cathodic reduction and high pressure hydrogenation was observed, providing a photocatalytic efficiency for H2 generation that is three times higher than that of either method individually. The researchers believe this work could help to improve the “blackening” of titania nanotubes for photocatalytic applications.
- Noble-Metal-Free Photocatalytic H2 Generation: Active and Inactive ‘Black’ TiO2 Nanotubes and Synergistic Effects,
Ning Liu, Christopher Schneider, Detlef Freitag, Eva M. Zolnhofer, Karsten Meyer, Patrik Schmuki,
Chem. Eur. J. 2016.
 C. Schneider, D. Freitag, U. Venkatesan, V. R. Marthala, M. Hartmann, B. Winter, E. Spiecker, A. Osvet, E. M. Zolnhofer, K. Meyer, T. Nakajima, X. Zhou, P. Schmuki, Angew. Chem. Int. Ed. 2014, 53(51), 14201–14205. DOI: 10.1002/anie.201408493