Nitrogen-doped SrTiO3/TiO2 composite photocatalysts for hydrogen production under visible light irradiation
Introduction
Energy and environment have become two important problems with the rapid development of industry. Photocatalytic reactions of semiconductor such as decomposition of water have been received great attention around the world [1], [2]. SrTiO3, one of the important photocatalysts, has been used for water splitting and mineralization of organic pollutants under ultraviolet (UV) irradiation, whereas it is active only in the UV region because of its wide band gap (3.2 eV). Therefore, its photocatalytic properties in UV light range have been investigated for several decades [3], [4]. Nowadays, the research on photocatalysis in the field of visible light has attracted many people's attention [5], [6], [7], [8], [9], and it has become a target of researchers to improve the photocatalytic activity of SrTiO3 and extend its optical absorption edge towards the visible light range. To our knowledge, researches of SrTiO3 on the photocatalytic hydrogen production are still scarce. We have not found any report on nitrogen-doped SrTiO3/TiO2 photocatalyst under visible light irradiation.
In this paper, nitrogen-doped SrTiO3 powders were prepared by solid phase method, and nitrogen-doped SrTiO3/TiO2 composite powders were prepared by sol–gel method and then Pt powders were further deposited to prepare Pt-loaded composite powders by hydrogen reduction method, whose photocatalytic activity for hydrogen production from oxalic acid solution was investigated under visible light irradiation. The effects of several factors such as the calcination temperatures of composite powders, and the contents of metal Pt on the rate of hydrogen production were studied.
Section snippets
Preparation of photocatalysts
According to our previous research [10], the nitrogen-doped SrTiO3 powders were prepared as follows: hexamethylenetetramine (HMT) was mixed with a perovskite SrTiO3 powder and grinded thoroughly in an agate mortar. The mass ratio of hexamethylenetetramine to SrTiO3 powders was 3 to 1. The mixed powder was packed in a lidded double alumina crucible and calcined at 450 °C under aerated conditions for 1 h. Nitrogen-doped SrTiO3 powders obtained was grinded in mortar after calcination.
Nitrogen-doped
Characterization of photocatalysts
XRD is used to investigate the phase structures of the samples. The XRD patterns of SrTiO3, N–SrTiO3, N–SrTiO3/TiO2 (350–600 °C) and Pt/N–SrTiO3–TiO2(400 °C, 2 wt.%) are shown, respectively in Fig. 1, Fig. 2. The average crystal size of SrTiO3 was determined to be 38.8 nm and nitrogen-doped SrTiO3 samples was 38.4 nm. The average crystal size of the TiO2 single crystal in composite catalyst calcined at 350, 400, 450, 500 and 600 °C was determined to be 8.5, 9.1, 9.5, 11.8 and 12.6 nm, respectively.
Conclusions
No hydrogen was produced for single SrTiO3 and TiO2 under visible light irradiation. SrTiO3 was doped nitrogen by solid phase method and further combined with TiO2 by sol–gel method. The photocatalytic hydrogen production activity was greatly improved under visible light irradiation. When the temperature of calcination is 400 °C, the optimized photocatalytic activity of hydrogen production under visible light irradiation can be achieved. Pt depositing greatly improved the photocatalytic
Acknowledgement
This research was financially supported by National Nature Science Foundation of China (No. 20876039), and the Scientific Research Foundation of Hunan Provincial Education Deparment, China (No. 08A026).
References (21)
- et al.
Mater. Res. Bull.
(1987) - et al.
J. Phys. Chem. Solids
(2007) - et al.
Appl. Catal. A: Gen.
(2005) - et al.
J. Photochem. Photobiol. A: Chem.
(2004) - et al.
J. Photochem. Photobiol. A: Chem.
(2001) - et al.
Sci. Technol. Adv. Mater.
(2004) - et al.
J. Photochem. Photobiol. A: Chem.
(2003) - et al.
Acta Chim. Sin.
(2005) - et al.
Nature
(1972) - et al.
Chem. Rev.
(1995)
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