Defects enhanced photocatalytic performances in SrTiO 3 using laser-melting treatment
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he Wei State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
Zhijian Penga) School of Engineering and Technology, China University of Geosciences, Beijing 100083, People’s Republic of China
Hui Wub) State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People’s Republic of China (Received 24 September 2016; accepted 17 November 2016)
SrTiO3 is an important photocatalyst for hydrogen evolution under solar light, a promising way to solve energy shortage. However, a rapid and efficient method to synthesize high-performance SrTiO3 used for this purpose still remains a challenge. In this work, we successfully prepared SrTiO3 catalyst with narrowed band gap through a rapid laser-melting method of a limited reaction time to seconds. The prepared SrTiO3 catalyst, which has a band gap of 3.05 eV, presents enhanced photocatalytic performance for hydrogen evolution under visible light. The evolution rate of laser-melted SrTiO3 is approximately 3.5 times higher than that of pristine SrTiO3. In addition, the magnetism in laser-melted SrTiO3 is also enhanced, which could not be observed in pristine SrTiO3, confirming the defective structure of the obtained laser-melted SrTiO3. The proposed laser-melting method will be a promising way to rapidly and efficiently synthesize homogeneous, solar-driven SrTiO3 photocatalyst for hydrogen evolution with rich defects and thus high-performance.
I. INTRODUCTION
Photocatalysis has drawn much attention because it is an efficient and energy-saving way to solve the shortage of nonrenewable energy resource,1 in which perovskite structured semiconductors have become one of the promising catalysts due to its low cost, high chemical stability, and excellent photocatalytic performance.2,3 To improve the photocatalytic performance of semiconductor catalysts, the band gap should be close to 1.23 eV, which, thus, can response to full spectrum of solar light. But the indirect band gap energy of SrTiO3 (STO) is 3.25 eV, while its direct band gap energy is 3.75 eV, which is active only under the region of ultraviolet light.4 And it is well-known that narrowing the band gap of semiconductor catalysts, adjusting the band gap position and increasing the activity
Contributing Editor: Xiaobo Chen Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2016.461
of electrons and holes can efficiently enhance their photocatalytic performance under visible light.5 So, in literature, many researchers have tried to tune the band gap of STO catalysts through doping with metal,6–8 or nonmetal,9,10 and combining with other cocatalysts.11,12 Doping efficiently creates a middle state in the band gap, which successfully narrows the band gap, thus letting the catalysts absorb more visible part of sunlight.13 For example, Xie et al. synthesized Fe-doped STO
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