催化学报 ›› 2016, Vol. 37 ›› Issue (10): 1787-1793.DOI: 10.1016/S1872-2067(16)62478-6

• 论文 • 上一篇    下一篇

高热稳定性二氧化硅包覆的Au25纳米簇的制备和催化应用

陈海军a,c, 刘超b, 王敏a, 张超锋a,c, 李杲b, 王峰a   

  1. a 中国科学院大连化学物理研究所催化基础国家重点实验室, 洁净能源国家实验室(筹), 辽宁大连 116023;
    b 中国科学院大连化学物理研究所催化基础国家重点实验室金催化研究中心, 辽宁大连 116023;
    c 中国科学院大学, 北京 100049
  • 收稿日期:2016-04-18 修回日期:2016-05-28 出版日期:2016-10-21 发布日期:2016-10-22
  • 通讯作者: Feng Wang, Gao Li
  • 基金资助:

    国家自然科学基金(21273231,21422308);大连市优秀青年基金(2014J11JH126);“青年千人”计划.

Thermally robust silica-enclosed Au25 nanocluster and its catalysis

Haijun Chena,c, Chao Liub, Min Wanga, Chaofeng Zhanga,c, Gao Lib, Feng Wanga   

  1. a State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    b Gold Catalysis Research Centre, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    c Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2016-04-18 Revised:2016-05-28 Online:2016-10-21 Published:2016-10-22
  • Contact: Feng Wang, Gao Li
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21273231, 21422308), Dalian Excellent Youth Foundation (2014J11JH126) (FW), and the Starting Funds of "Thousand Youth Talents Plan" (GL).

摘要:

具有独特的电子和几何结构,原子精确控制的金纳米簇(<2 nm)成为一种新的具有广泛研究和应用前景的纳米催化剂.负载在氧化物表面的金纳米簇通常会在高于300℃时聚集或长大.人们已经通过多种方法成功制备了对于非原子精确控制的热稳定性的金纳米颗粒.主要包括利用金属与载体强相互作用,用可还原的金属氧化物来稳定金纳米颗粒;利用物理阻隔作用使用高比表面积的载体或制备核壳、纳米粒子镶嵌在载体中来稳定金纳米颗粒.对于原子精确控制的金纳米簇,由于其外边包覆着一层配体,将其负载到载体上时要保证配体不被破坏才能保证金纳米簇的结构完整性,负载后通常要除去配体才能使催化活性位曝露出来.目前,高热稳定性(>300℃)的金纳米簇的制备方法还较少.
由于金与SiO2相互作用较弱,将超小(<2 nm)的金纳米粒子包覆于其中非常困难.因此,本文首先制备了1.3 nm的含有硅酯键的巯基配体(3-巯丙基三甲氧基硅烷)保护的Au25[SC3H6Si(OCH33]18,然后将其在刚成核的SiO2表面与正硅酸四乙酯共水解,得到了既保留了Au25的完整结构,又避免了Au25之间相互水解的Au25(SC3H6SiO3)18@SiO2纳米材料.漫反射固体紫外-可见光谱证明了Au25在包覆完成后结构的完整性.透射电镜结果表明,Au25纳米簇焙烧至400℃未发生明显聚集长大.对硝基苯酚还原实验结果表明,不同温度处理后的Au25@SiO2配体在200℃开始脱除,温度高于传统的负载型Au25催化剂,表明Au25是在SiO2内部而不是在表面,从而使配体不易离去.400℃处理后的Au25@SiO2对4-硝基苯酚还原表现出最高的反应活性,表明该纳米簇在400℃处理后没有发生明显聚集长大.

关键词: 金原子簇, Au25, 热稳定性, 二氧化硅, 氢化

Abstract:

Well-defined gold nanoclusters with average size less than 2 nm have emerged as a new and novel catalyst. The gold nanocluster loaded on the oxide surface usually aggregates to larger particles at high temperature (>300℃), which is caused by the removal of the surface ligands. We herein present a novel method to prepare Au25 cluster catalyst (~1.3 nm) with high thermal stability (up to 400℃). Au25@SiO2 is synthesized via a co-hydrolyzing reaction of Au25[SC3H6Si(OCH3)3]18 and tetraethyl orthosilicate, and then it is treated at different temperature (e.g., 200, 300, 400℃) in air to remove the organic ligands. Au25@SiO2 is well characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and diffuse reflectance UV-vis spectroscopy. Further, the Au25@SiO2 catalysts are investigated in the hydrogenation of p-nitrophenol into p-aminophenol.

Key words: Gold nanocluster, Au25, Thermal stability, Silica, Hydrogenation