Photocatalytic activity of MTiO 3 (M = Ca, Ni, and Zn) nanocrystals for water decomposition to hydrogen
- PDF / 620,137 Bytes
- 7 Pages / 584.957 x 782.986 pts Page_size
- 2 Downloads / 198 Views
MTiO3 (M 5 Ca, Ni, and Zn) nanocrystals were prepared via a facile ethylene glycol-mediated synthesis route followed by calcination in air. The structures and morphologies of nanocrystals were characterized by x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results indicated that CaTiO3 and NiTiO3 are orthorhombic phase, while the ZnTiO3 is orthorhombic phase. The activity of the CaTiO3 nanocrystals for water splitting into H2 was obviously higher than those of the NiTiO3 and ZnTiO3 nanocrystals, which could be attributed to the more negative conduction band position of CaTiO3 than NiTiO3 and ZnTiO3. The Brunauer–Emmett–Teller system-based surface areas of samples are 19.03, 21.13, and 4.17 m2/g for CaTiO3, NiTiO3, and ZnTiO3 nanocrystals, respectively. In addition, the activity of the CaTiO3 nanocrystals increased with increase in the sintering temperature of samples.
I. INTRODUCTION
Hydrogen has been identified as a potential energy carrier in many low greenhouse gas energy scenarios due to its high energy capacity and environmental friendliness.1–8 In hydrogen energy systems, potential sources of hydrogen include conversion from biomass or from electrolysis, photolysis, and thermolysis of water. It is well known that hydrogen produced from water does not present the challenge of unwanted emissions at the point of conversion, but energy must be supplied from an external resource.9 If this energy can be obtained from solar energy, hydrogen can then be considered a green energy alternative capable of powering everything from laptops to submarines. Photocatalytic hydrogen production from water using a semiconductor catalyst has attracted a tremendous amount of interest since the discovery of water splitting on a TiO2 electrode.10–15 Thermodynamically, water splitting into H2 and O2 is an uphill reaction, accompanied by a large positive change in the Gibbs free energy. The efficiency of water splitting is determined by the band gap and band structure of the semiconductor and the electron transfer process. Over the past several decades, many photocatalysts have been found to have photocatalytic activities for photocatalytic hydrogen production.16–22 In particular, interest has been directed toward nanostructures with high photocatalytic activity because of their large surface areas, unique photochemical and photophysical a)
Address all correspondence to this author. e-mail: wanggf [email protected] DOI: 10.1557/jmr.2014.110 J. Mater. Res., Vol. 29, No. 11, Jun 14, 2014
http://journals.cambridge.org
Downloaded: 26 Feb 2015
properties, and electron-transport properties.23–29 However, new and effective photocatalysts are still to be perfected owing to the fact that present photocatalysts are unstable, suffer from self-oxidization effect, are expensive, and involve fussy preparation methods and energy consumption. Among various materials, layered perovskite-type oxides have attracted considerable attention due to their unique optical properties and excellent ph
Data Loading...
