催化学报 ›› 2018, Vol. 39 ›› Issue (3): 395-400.DOI: 10.1016/S1872-2067(17)62963-2

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两步水热法合成Sn2Nb2O7纳米晶及其高效可见光分解水制氢性能

周超a, 施润a,b, 尚露a, 吴骊珠a, 佟振合a, 张铁锐a,b   

  1. a 中国科学院理化技术研究所, 中国科学院光化学转换与功能材料重点实验室, 北京 100190;
    b 中国科学院大学, 北京 100049
  • 收稿日期:2017-09-27 修回日期:2017-10-29 出版日期:2018-03-18 发布日期:2018-03-10
  • 通讯作者: 张铁锐
  • 基金资助:

    国家重点基础研究发展计划(973计划,2014CB239402,2013CB834505);国家重点研发计划纳米科技重点专项(2016YFB0600901,2017YFA0206904,2017YFA0206900);国家自然科学基金(51772305,51572270,U1662118,21401207);中国科学院战略性先导科技专项(B类)(XDB17000000);中国科学院青年创新促进会.

Two-step hydrothermal synthesis of Sn2Nb2O7 nanocrystals with enhanced visible-light-driven H2 evolution activity

Chao Zhoua, Run Shia,b, Lu Shanga, Li-Zhu Wua, Chen-Ho Tunga, Tierui Zhanga,b   

  1. a Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-09-27 Revised:2017-10-29 Online:2018-03-18 Published:2018-03-10
  • Contact: 10.1016/S1872-2067(17)62963-2
  • Supported by:

    This work was supported by the Ministry of Science and Technology of China (2014CB239402, 2013CB834505), the National Key Projects for Fundamental Research and Development of China (2016YFB0600901, 2017YFA0206904, 2017YFA0206900), the National Natural Science Foundation of China (51772305, 51572270, U1662118, 21401207), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17000000), and the Youth Innovation Promotion Association of the CAS.

摘要:

铌基半导体光催化材料因其具有独特的晶体结构和能带结构在光催化分解水制氢领域受到科研工作者的高度关注.然而,大多数铌基半导体光催化剂仅能够在紫外光驱动下实现光催化分解水制氢,具有可见光响应的铌基半导体光催化剂不仅数量少而且活性较低,因此发展新型纳米铌基半导体光催化剂并实现其高效可见光催化分解水产氢具有重要的学术和实用意义.具有烧绿石构型的Sn2Nb2O7材料由于具有较窄的禁带宽度(2.4eV)和合适的导带和价带电势在可见光催化分解水制氢方面引起了科研人员广泛的兴趣.然而,目前报道的利用高温固相法制备的块体Sn2Nb2O7材料由于颗粒尺寸较大和比表面积较小而导致光催化活性较差.因此,发展一种简便高效的制备方法实现纳米Sn2Nb2O7材料的可控制备进而提高其可见光催化活性仍具有一定的挑战性.
我们发展了一种简便的两步水热合成方法实现了Sn2Nb2O7纳米晶的可控制备.扫描电镜和透射电镜测试结果表明,通过两步水热法得到的Sn2Nb2O7纳米颗粒具有较好分散度,其平均颗粒尺寸为20nm.X射线衍射测试结果也进一步证明,通过两步水热法可以实现Sn2Nb2O7纳米晶的可控制备.比表面积测试结果表明,Sn2Nb2O7纳米晶的比表面积约为52.2m2/g,远远大于固相法制备的块体Sn2Nb2O7材料(2.3m2/g).大量研究表明,大的比表面积有利于半导体催化材料催化活性的提升.通过考查所制备的Sn2Nb2O7纳米晶的可见光分解水制氢能力,对其催化性能进行了评价.研究结果表明,以乳酸为空穴消耗剂,负载0.3wt.% Pt纳米颗粒作为助催化剂的Sn2Nb2O7纳米晶表现出优异的可见光催化分解水产氢性能,其产氢速率是块体Sn2Nb2O7材料的5.5倍.Sn2Nb2O7纳米晶可见光催化分解水产氢性能提高的主要原因是其具有高分散度的纳米颗粒、较大的比表面积和更正的价带电势.首先,颗粒尺寸的纳米化能够显著减小光生电子和空穴的迁移距离,实现光生载流子快速迁移到催化剂表面进而参与催化反应;其次,大的比表面积能够提供更多的催化活性位点,进而有利于催化活性的提高;最后,X射线光电子能谱测试表明,Sn2Nb2O7纳米晶具有更正的价带电势,研究表明,价带电势越正,其光生空穴氧化能力越强.在光催化分解水制氢过程中,具有较强氧化能力的光生空穴通过与空穴牺牲剂乳酸快速反应而被消耗掉,抑制了光生电子与空穴的复合,进而导致其具有较高的光催化产氢活性.

关键词: 水热合成, Sn2Nb2O7, 光催化, 分解水, 可见光驱动

Abstract:

We use a two-step hydrothermal method to successfully synthesize Sn2Nb2O7 nanocrystals with an average size of approximately 20 nm. The as-obtained samples are characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, Brunauer-Emmett-Teller analysis, scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of the Sn2Nb2O7 nanocrystals is evaluated by photocatalytic water splitting under visible light irradiation. The Sn2Nb2O7 nanocrystals with a large surface area of 52.2 m2/g show an enhanced visible-light-driven photocatalytic H2 production activity, approximately 5.5 times higher than that of bulk Sn2Nb2O7 powder. The higher photocatalytic activity of Sn2Nb2O7 nanocrystals is mainly attributed to its relatively high dispersity of nanosized particles and larger specific surface area when compared with the bulk powder.

Key words: Hydrothermal synthesis, Sn2Nb2O7, Photocatalysis, Water splitting, Visible-light-driven