直接溶液还原法快速合成金、钯、铂气凝胶的研究
Summary
提出了一种快速、直接的基于溶液的还原合成方法, 用于获得金、钯和 Pt 气凝胶。
Abstract
本文提出了一种通过快速直接溶液还原法合成金、钯、铂气凝胶的方法。在 1:1 (v/v) 比值中, 各种前体贵金属离子与还原剂的结合导致金属凝胶在几秒到几分钟内形成, 与其他技术如溶胶-凝胶相比, 合成时间更长。在离心管或小容积锥形管中进行还原步骤, 有利于形成凝胶成型的成核、生长、致密化、融合、平衡模型, 最终凝胶几何小于初始反应体积。这种方法利用积极的氢气演化作为还原步骤的副产品, 并作为试剂浓度的结果。用电化学阻抗谱和循环伏安法确定了溶剂可接近的比表面积。经冲洗和冷冻干燥后, 用扫描电镜、X 射线衍射和氮气吸附法对产生的气凝胶结构进行了检测。合成方法和表征技术导致气凝胶韧带大小的密切对应。本发明的贵金属气凝胶的合成方法表明, 采用快速直接还原法可实现高比表面积石柱。
Introduction
广泛的能量存储和转换, 催化和传感器应用得益于三维金属纳米结构, 提供控制化学反应性, 和大众运输性能1,2, 3,4,5。这样的3维金属纳米结构进一步提高电导率, 延性, 延展性和强度8,9。集成到设备需要材料是自由的或与支持材料结合。将纳米材料纳入支撑结构提供了一种尽量减少活性材料的方法, 但在设备操作10、11期间可能会受到弱吸附和最终结块的影响。
虽然有各种合成方法来控制单个纳米粒的大小和形状, 但很少有方法能够控制连续的3维纳米材料12、13、14。贵金属3维纳米结构已形成通过 dithiol 连接单分散纳米粒子, 溶胶-凝胶形成, 纳米粒子聚结, 复合材料, 纳米链, biotemplating15,16,17,18. 这些方法中有许多需要在几天到几周的时间内合成所需材料。从直接还原前体盐溶液中合成的贵金属 nanofoams, 合成时间较快, 且长度为上百微米的短量程, 但需要机械压制以进行设备集成。19,20。
第一次报告的基斯特勒, 气凝胶提供了一个合成途径, 以实现多孔结构的高比表面积, 是数量级低于其散装材料相对密度小于21,22,23.将3维结构扩展到散装材料的宏观长度尺度, 比需要支持材料或机械加工的纳米颗粒骨料或 nanofoams 具有优势。虽然气凝胶提供了一种控制孔隙度和颗粒特征大小的合成途径, 但是, 延长合成时间, 在某些情况下使用封盖剂或连结分子, 增加了整体加工步骤和时间。
本文提出了一种通过快速直接溶液还原法合成金、钯、铂气凝胶的方法24。将各种前体贵金属离子与还原剂相结合, 在 1:1 (v/v) 比值下, 在几秒到几分钟内形成金属凝胶, 与其他技术如溶胶-凝胶相比, 合成时间更长。使用离心管或小容积圆锥管, 利用积极的氢气演化作为副产品的减少步骤, 促进提出的核, 生长, 致密化, 融合, 平衡模型的凝胶形成。用扫描电镜图像分析、X 射线衍射、氮气吸附、电化学阻抗谱和循环伏安法确定气凝胶纳米结构特征尺寸的密切关系。用电化学阻抗谱和循环伏安法确定了溶剂可接近的比表面积。本发明的贵金属气凝胶的合成方法表明, 采用快速直接还原法可实现高比表面积石柱。
Protocol
警告: 使用前请查阅所有相关的安全数据表 (SDS)。在进行化学反应时, 使用适当的安全措施, 包括使用油烟机和个人防护设备。快速的氢气演化会导致反应管产生高压, 从而导致瓶盖的弹出和溶液喷出。确保反应管帽保持在协议规定的状态下打开。 1. 金属凝胶制剂 金属离子溶液的制备。 准备2毫升以下盐的 0.1 M 解答: HAuCl4· 3H2O 和 Na<…
Representative Results
金属离子和还原剂溶液的加入, 使溶液立即变成深黑色, 并有剧烈的气体演化。观察反应进展表明, 建议的凝胶形成机制如图 1所示。凝胶形成通过五步骤 1) 纳米粒核, 2) 生长, 3) 致密化, 4) 融合, 和 5) 平衡。前四步被观察到发生在反应的头几分钟, 与平衡第五步在 3-6 h 期间进行, 而凝胶保持在还原剂解决方案, 并继续在去离子水冲洗。图…
Discussion
这里提出的贵金属气凝胶合成方法, 导致了多孔, 高表面积石柱的快速形成, 可比较慢的合成技术。1:1 (v/v) 金属离子溶液, 以降低剂溶液比是至关重要的, 以促进拟议的凝胶形成模型。快速氢气体演化作为金属离子电化学还原的副产品, 作为二次还原剂, 促进了凝胶形成过程中生长纳米粒子的致密化和融合。考虑到表 1中所示的许多合成组合不会导致凝胶的形成, 选择金属离子类型和还原?…
Divulgaciones
The authors have nothing to disclose.
Acknowledgements
作者感谢 Deryn 在气凝胶技术方面的灵感和技术洞察力, 以及陆军研究实验室-传感器和电子设备局, 克里斯托弗. 海恩斯博士在军备研究中的博士。开发和工程中心, 美国陆军 RDECOM-ARDEC, 和斯蒂芬博士 Bartolucci 在美国陆军贝尼特实验室为他们提供援助。这项工作得到了美国陆军学院西点军校教师发展研究基金的资助。
Materials
| HAuCl4Ÿ•3H2O | Sigma-Aldrich | 16961-25-4 | |
| Na2PdCl4 | Sigma-Aldrich | 13820-40-1 | |
| K2PtCl6 | Sigma-Aldrich | 16921-30-5 | |
| Pd(NH3)4Cl2 | Sigma-Aldrich | 13933-31-8 | |
| K2PtCl4 | Sigma-Aldrich | 10025-99-7 | |
| Pt(NH3)4Cl2Ÿ•H2O | Sigma-Aldrich | 13933-31-8 | |
| dimethylamine borane (DMAB) | Sigma-Aldrich | 74-94-2 | |
| NaBH4 | Sigma-Aldrich | 16940-66-2 | |
| NaH2PO2Ÿ•H2O | Sigma-Aldrich | 10039-56-2 | |
| Ethanol | Sigma-Aldrich | 792780 | |
| Snap Cap Microcentrifuge Tubes, 2.0 mL | Cole Parmer | UX-06333-70 | |
| Snap Cap Microcentrifuge Tubes, 1.7 mL | Cole Parmer | UX-06333-60 | |
| Conical Centrifuge Tubes 15mL | Stellar Scientific | T15-101 | |
| Ag/AgCl Reference Electrode | BASi | MF-2052 | |
| Pt wire electrode | BASi | MF-4130 | |
| Miccrostop Lacquer | Tober Chemical Division | NA | |
| Potentiostat | Biologic-USA | VMP-3 | Electrochemical analysis-EIS, CV |
| Freeze Dryer | Labconco | Freezone 2.5 Liter | Aerogel freeze drying |
| XRD | PanAlytical | Empyrean | X-ray diffractometry |
| Surface and Pore Analyzer | Quantachrome | NOVA 4000e | Nitrogen gas adsorption |
| ImageJ, Image analysis software | National Institute of Health | NA | SEM image analysis |
Referencias
- Rolison, D. Catalytic Nanoarchitectures-the Importance of Nothing and the Unimportance of Periodicity. Science. 299, 1698-1701 (2003).
- Wei, T., Chen, C., Chang, K., Lu, S., Hu, C. Cobalt Oxide Aerogels of Ideal Supercapacitive Properties Prepared with an Epoxide Synthetic Route. Chemistry of Materials. 21, 3228-3233 (2009).
- Anderson, M., Morris, C., Stroud, R., Merzbacher, C., Rolison, D. Colloidal Gold Aerogels: Preparation, Properties, and Characterization. Langmuir. 15, 674-681 (1999).
- Gaponik, N., Herrmann, A., Eychmuller, A. Colloidal Nanocrystal-Based Gels and Aerogels: Material Aspects and Application Perspectives. Journal of Physical Chemistry Letters. 3, 8-17 (2012).
- Olsson, R., et al. Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates. Nature Nanotechnology. 5, 584-588 (2010).
- Anderson, M., Morris, C., Stroud, R., Merzbacher, C., Rolison, D. Colloidal Gold Aerogels: Preparation, Properties, and Characterization. Langmuir. 15, 674-681 (1999).
- Gaponik, N., Herrmann, A., Eychmuller, A. Colloidal Nanocrystal-Based Gels and Aerogels: Material Aspects and Application Perspectives. Journal of Physical Chemistry Letters. 3, 8-17 (2012).
- Hodge, A., Hayes, J., Cao, J., Biener, J., Hamza, A. Characterization and Mechanical Behavior of Nanoporous Gold. Advanced Engineering Materials. 8, 853-857 (2006).
- Hodge, A., et al. Scaling equation for yield strength of nanoporous open-cell foams. Acta Materialia. 55, 1343-1349 (2007).
- Ambrosi, A., Chua, C., Bonanni, A., Pumera, M. Electrochemistry of Graphene and Related Materials. Chemical Reviews. 114, 7150-7188 (2014).
- Maillard, F., et al. Influence of particle agglomeration on the catalytic activity of carbon-supported Pt nanoparticles in CO monolayer oxidation. Physical Chemistry Chemical Physics. 7, 385-393 (2005).
- Zhao, P., Li, N., Astruc, D. State of the art in gold nanoparticle synthesis. Coordination Chemistry Reviews. 257, 638-665 (2013).
- Wen, D., et al. Controlling the Growth of Palladium Aerogels with High-Performance toward Bioelectrocatalytic Oxidation of Glucose. Journal of American Chemical Society. 136, 2727-2730 (2014).
- Jana, N., Gearheart, L., Murphy, C. Seed-Mediated Growth Approach for Shape-Controlled Synthesis of Spheroidal and Rod-like Gold Nanoparticles Using a Surfactant Template. Advanced Materials. 13, 1389-1392 (2001).
- Ding, Y., Chen, M., Erlebacher, J. Metallic Mesoporous Nanocomposites for Electrocatalysis. Journal of American Chemical Society. 126, 6876-6877 (2004).
- Liu, W., et al. High-Performance Electrocatalysis on Palladium Aerogels. Angewandte Chemie. International Edition. 51, 5743-5747 (2012).
- Herrmann, A., et al. Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles. Chemistry of Materials. 26, 1074-1083 (2014).
- Ameen, K., Rajasekharan, T., Rajasekharan, M. Grain size dependence of physico-optical properties of nanometallic silver in silica aerogel matrix. Journal of Non-Crystalline Solids. 352, 737-746 (2006).
- Qin, G., et al. A Facile and Template-Free Method to Prepare Mesoporous Gold Sponge and Its Pore Size Control. Journal of Physical Chemistry C. 112, 10352-10358 (2008).
- Krishna, K., Sandeep, C., Philip, R., Eswaramoorthy, M. Mixing Does the Magic: A Rapid Synthesis of High Surface Area Noble Metal Nanosponges Showing Broadband Nonlinear Optical Response. ACS Nanotechnology. 5, 2681-2688 (2010).
- Kistler, S. Coherent Expanded Aerogels and Jellies. Nature. 127, 741-741 (1931).
- Du, A., Zhou, B., Zhang, Z., Shen, J. A Special Material or a New State of Matter: A Review and Reconsideration of the Aerogel. Materials. 6, 941-968 (2013).
- Tappan, B., Steiner, S., Luther, E. Nanoporous Metal Foams. Angewandte Chemie. International Edition. 49, 4544-4565 (2010).
- Burpo, F., et al. Direct solution-based reduction synthesis of Au, Pd, and Pt aerogels. Journal of Materials Research. 32, 4153-4165 (2017).
- Ostwald, W. Blocking of Ostwald ripening allowing long-term stabilization. PhysicalChemistry. 37, 385 (1901).
- Wang, S., Tseng, W. Aggregate structure and crystallite size of platinum nanoparticles synthesized by ethanol reduction. Journal of Nanoparticle Research. 11, 947-953 (2009).
- Schneider, C., Rasband, W., Eliceiri, K. NIH Image to ImageJ: 25 years of image analysis. Nature Methods. 9, 671-675 (2012).
- Thommes, M., et al. Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). Pure and Applied Chemistry. 87, 1051-1069 (2015).
- Barrett, E., Joyner, L., Halenda, P. The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms. Journal of the American Chemical Society. 73, 373-380 (1951).
- Brunauer, B., Emmett, P., Teller, P. Adsorption of Gases in Multimolecular Layers. Journal of the American Chemical Society. 60, 309-319 (1938).
- Herrmann, A., et al. Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles. Chemistry of Materials. 26, 1074-1083 (2014).
- Kornyshev, A., Irbakh, M. Double-layer capacitance on a rough metal surface. Physical Review E. 53, 6192-6199 (1996).
- Bisquert, J. Influence of the boundaries in the impedance of porous film electrodes. Physical Chemistry Chemical Physics. 2, 4185-4192 (2000).
- Bisquert, J. Theory of the Impedance of Electron Diffusion and Recombination in a Thin Layer. Journal of Physical Chemistry B. 106, 325-333 (2002).
- Lu, K., Yuan, L., Xin, X., Xu, Y. Hybridization of graphene oxide with commercial graphene for constructing 3D metal-free aerogel with enhanced photocatalysis. Applied Catalysis B. 226, 16-22 (2018).
- Nystron, G., Roder, L., Fernandez-Ronco, M., Mezzenga, R. Amyloid Templated Organic Inorganic Hybrid Aerogels. Advanced Functional Materials. , 1703609-1703620 (2017).
Citar este artículo
Burpo, F. J., Nagelli, E. A., Morris, L. A., McClure, J. P., Ryu, M. Y., Palmer, J. L. A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction. J. Vis. Exp. (136), e57875, doi:10.3791/57875 (2018).