Name: synthesis method for cellulose nanofiber biotemplated palladium composite aerogels
Uploaded: 2019-05-09T13:00:00
Description: Watch this Scientific Journal Video about Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels at JoVE.com

The authors are grateful to Dr. Stephen Bartolucci and Dr. Joshua Maurer at the U.S. Army Benet Laboratories for the use of their scanning electron microscope. This work was supported by a Faculty Development Research Fund grant from the United States Military Academy, West Point.

&#8203;CAUTION: Consult all relevant safety data sheets (SDS) before use. Use appropriate safety practices when performing chemical reactions, to include the use of a fume hood and personal protective equipment (PPE). Rapid hydrogen gas evolution can cause high pressure in reaction tubes causing caps to pop and solutions to spray out. Ensure that reaction tubes remain open and pointed away from the experimenter as specified in the protocol.
1. Cellulose nanofiber hydrogel preparation
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	<li>Kistler, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coherent+Expanded+Aerogels+and+Jellies.">Coherent Expanded Aerogels and Jellies.</a> Nature. 127, 741 (1931).</li><li>Du, A., Zhou, B., Zhang, Z., Shen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Special+Material+or+a+New+State+of+Matter:+A+Review+and+Reconsideration+of+the+Aerogel.">A Special Material or a New State of Matter: A Review and Reconsideration of the Aerogel.</a> Materials. 6 (3), 941 (2013).</li><li>Tappan, B. C., Steiner, S. A., Luther, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoporous+Metal+Foams.">Nanoporous Metal Foams.</a> Angewandte Chemie International Edition. 49 (27), 4544-4565 (2010).</li><li>Bigall, N. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogels+and+Aerogels+from+Noble+Metal+Nanoparticles.">Hydrogels and Aerogels from Noble Metal Nanoparticles.</a> Angewandte Chemie International Edition. 48 (51), 9731-9734 (2009).</li><li>Ranmohotti, K. G. S., Gao, X., Arachchige, I. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salt-Mediated+Self-Assembly+of+Metal+Nanoshells+into+Monolithic+Aerogel+Frameworks.">Salt-Mediated Self-Assembly of Metal Nanoshells into Monolithic Aerogel Frameworks.</a> Chemistry of Materials. 25 (17), 3528-3534 (2013).</li><li>Gao, X., Esteves, R. J., Luong, T. T. H., Jaini, R., Arachchige, I. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidation-Induced+Self-Assembly+of+Ag+Nanoshells+into+Transparent+and+Opaque+Ag+Hydrogels+and+Aerogels.">Oxidation-Induced Self-Assembly of Ag Nanoshells into Transparent and Opaque Ag Hydrogels and Aerogels.</a> Journal of the American Chemical Society. 136 (22), 7993-8002 (2014).</li><li>Herrmann, A. -. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multimetallic+Aerogels+by+Template-Free+Self-Assembly+of+Au,+Ag,+Pt,+and+Pd+Nanoparticles.">Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles.</a> Chemistry of Materials. 26 (2), 1074-1083 (2014).</li><li>Ding, Y., Chen, M., Erlebacher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metallic+Mesoporous+Nanocomposites+for+Electrocatalysis.">Metallic Mesoporous Nanocomposites for Electrocatalysis.</a> Journal of the American Chemical Society. 126 (22), 6876-6877 (2004).</li><li>Liu, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Performance+Electrocatalysis+on+Palladium+Aerogels.">High-Performance Electrocatalysis on Palladium Aerogels.</a> Angewandte Chemie International Edition. 51 (23), 5743-5747 (2012).</li><li>Shafaei Douk, A., Saravani, H., Noroozifar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+assembly+of+building+blocks+for+the+fabrication+of+Pd+aerogel+as+a+high+performance+electrocatalyst+toward+ethanol+oxidation.">Three-dimensional assembly of building blocks for the fabrication of Pd aerogel as a high performance electrocatalyst toward ethanol oxidation.</a> Electrochimica Acta. 275, 182-191 (2018).</li><li>Burpo, F. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+solution-based+reduction+synthesis+of+Au,+Pd,+and+Pt+aerogels.">Direct solution-based reduction synthesis of Au, Pd, and Pt aerogels.</a> Journal of Materials Research. 32 (22), 4153-4165 (2017).</li><li>Burpo, F. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Rapid+Synthesis+Method+for+Au,+Pd,+and+Pt+Aerogels+Via+Direct+Solution-Based+Reduction.">A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction.</a> JoVE. (136), e57875 (2018).</li><li>Qin, G. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Facile+and+Template-Free+Method+to+Prepare+Mesoporous+Gold+Sponge+and+Its+Pore+Size+Control.">A Facile and Template-Free Method to Prepare Mesoporous Gold Sponge and Its Pore Size Control.</a> The Journal of Physical Chemistry C. 112 (28), 10352-10358 (2008).</li><li>Hench, L. L., West, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Sol-Gel+Process.">The Sol-Gel Process.</a> Chemical Reviews. 90 (1), 33-72 (1990).</li><li>Sotiropoulou, S., Sierra-Sastre, Y., Mark, S. S., Batt, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biotemplated+Nanostructured+Materials.">Biotemplated Nanostructured Materials.</a> Chemistry of Materials. 20 (3), 821-834 (2008).</li><li>Huang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bio-inspired+synthesis+of+metal+nanomaterials+and+applications.">Bio-inspired synthesis of metal nanomaterials and applications.</a> Chemical Society Reviews. 44 (17), 6330-6374 (2015).</li><li>Burpo, F. J., Mitropoulos, A. N., Nagelli, E. A., Ryu, M. Y., Palmer, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gelatin+biotemplated+platinum+aerogels.">Gelatin biotemplated platinum aerogels.</a> MRS Advances. 10, 1-6 (2018).</li><li>Jarvis, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellulose+stacks+up.">Cellulose stacks up.</a> Nature. 426, 611 (2003).</li><li>Sir&#243;, I., Plackett, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfibrillated+cellulose+and+new+nanocomposite+materials:+a+review.">Microfibrillated cellulose and new nanocomposite materials: a review.</a> Cellulose. 17 (3), 459-494 (2010).</li><li>Dufresne, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanocellulose:+a+new+ageless+bionanomaterial.">Nanocellulose: a new ageless bionanomaterial.</a> Materials Today. 16 (6), 220-227 (2013).</li><li>Grishkewich, N., Mohammed, N., Tang, J., Tam, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+the+application+of+cellulose+nanocrystals.">Recent advances in the application of cellulose nanocrystals.</a> Current Opinion in Colloid &amp; Interface Science. 29, 32-45 (2017).</li><li>Eyley, S., Thielemans, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+modification+of+cellulose+nanocrystals.">Surface modification of cellulose nanocrystals.</a> Nanoscale. 6 (14), 7764-7779 (2014).</li><li>Missoum, K., Belgacem, M., Bras, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanofibrillated+Cellulose+Surface+Modification.">Nanofibrillated Cellulose Surface Modification.</a> A Review. Materials. 6 (5), 1745 (2013).</li><li>Li, Z., Yao, C., Wang, F., Cai, Z., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellulose+nanofiber-templated+three-dimension+TiO2+hierarchical+nanowire+network+for+photoelectrochemical+photoanode.">Cellulose nanofiber-templated three-dimension TiO2 hierarchical nanowire network for photoelectrochemical photoanode.</a> Nanotechnology. 25 (50), 504005 (2014).</li><li>Hal Koga, ., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uniformly+connected+conductive+networks+on+cellulose+nanofiber+paper+for+transparent+paper+electronics.">Uniformly connected conductive networks on cellulose nanofiber paper for transparent paper electronics.</a> Npg Asia Materials. 6, 93 (2014).</li><li>Fal Burpo, ., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellulose+Nanofiber+Biotemplated+Palladium+Composite+Aerogels.">Cellulose Nanofiber Biotemplated Palladium Composite Aerogels.</a> Molecules. 23 (6), 1405 (2018).</li><li>Gu, J., Hu, C., Zhang, W., Dichiara, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reagentless+preparation+of+shape+memory+cellulose+nanofibril+aerogels+decorated+with+Pd+nanoparticles+and+their+application+in+dye+discoloration.">Reagentless preparation of shape memory cellulose nanofibril aerogels decorated with Pd nanoparticles and their application in dye discoloration.</a> Applied Catalysis B: Environmental. 237, 482-490 (2018).</li><li>Coates, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=in+A+Practical+Approach.">in A Practical Approach.</a> In Encyclopedia of Analytical Chemistry .doi:10.1002/9780470027318.a5606 (ed. , (2006).</li><li>Sal Wang, ., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellulose+nanofiber-assisted+dispersion+of+cellulose+nanocrystals@polyaniline+in+water+and+its+conductive+films).">Cellulose nanofiber-assisted dispersion of cellulose nanocrystals@polyaniline in water and its conductive films).</a> RSC Advances. 6 (12), 10168-10174 (2016).</li><li>Grabarek, Z., Gergely, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zero-length+crosslinking+procedure+with+the+use+of+active+esters.">Zero-length crosslinking procedure with the use of active esters.</a> Analytical Biochemistry. 185 (1), 131-135 (1990).</li><li>Shabanpour, B., Kazemi, M., Ojagh, S. M., Pourashouri, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+cellulose+nanofibers+as+reinforce+in+edible+fish+myofibrillar+protein+nanocomposite+films.">Bacterial cellulose nanofibers as reinforce in edible fish myofibrillar protein nanocomposite films.</a> International Journal of Biological Macromolecules. 117, 742-751 (2018).</li><li>Brunauer, B., Emmett, P., Teller, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorption+of+gases+in+multimolecular+layers.">Adsorption of gases in multimolecular layers.</a> Journal of the American Chemical Society. 60, (1938).</li><li>Barrett, E., Joyner, L., Halenda, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+determination+of+pore+volume+and+area+distributions+in+porous+substances.">The determination of pore volume and area distributions in porous substances.</a> I. Computations. 73, (1951).</li></ol>

The noble metal cellulose nanofiber biotemplated aerogel synthesis method presented here results in stable aerogel composites with tunable metal composition. The covalent crosslinking of the compacted cellulose nanofibers after centrifugation results in hydrogels that are mechanically durable during the subsequent synthesis steps of palladium ion equilibration, electrochemical reduction, rinsing, solvent exchange, and supercritical drying. The hydrogel stability is vital during the electrochemical reduction step given th...

Aerogels, first reported by Kistler, offer porous structures orders of magnitude less dense than their bulk material counterparts1,2,3. Noble metal aerogels have attracted scientific interest for their potential in power and energy, catalytic, and sensor applications. Noble metal aerogels have recently been synthesized via two basic strategies. One strategy is to induce the coalescence of pre-formed nanoparticles4,5,6,7. Sol-gel coalescence of nanoparticles can be driven by linker molecules, changes in solution ionic strength, or simple nanoparticle surface free energy minimization7,8,9. The other strategy is to form aerogels in a single reduction step from metal precursor solutions9,10,11,12,13. This approach has also been used to form bimetallic and alloy noble metal aerogels. The first strategy is generally slow and may require up to many weeks for nanoparticle coalescence14. The direct reduction approach, while generally more rapid, suffers from poor shape control over the macroscopic aerogel monolith.
One possible synthesis approach to address challenges with control of noble metal aerogel macroscopic shape and nanostructure is to employ biotemplating15. Biotemplating uses biological molecules ranging from collagen, gelatin, DNA, viruses, to cellulose to provide a shape-directing template for the synthesis of nanostructures, where the resulting metal-based nanostructures assume the geometry of the biological template molecule16,17. Cellulose nanofibers are appealing as a biotemplate given the high natural abundance of cellulosic materials, their high aspect ratio linear geometry, and ability to chemically functionalize their glucose monomers18,19,20,21,22,23. Cellulose nanofibers (CNF) have been used to synthesize three dimensional TiO2 nanowires for photoanodes24, silver nanowires for transparent paper electronics25, and palladium aerogel composites for catalysis26. Further, TEMPO-oxidized cellulose nanofibers have been used both as a biotemplate and reducing agent in the preparation of palladium decorated CNF aerogels27.
Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented26. Fragile aerogels with poor shape control occurs for a range noble metal aerogel synthesis methods. Carboxymethylated cellulose nanofibers (CNFs) used to form a covalent hydrogel allow for the reduction of metal ions such as palladium on the CNFs providing control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Carboxymethylated cellulose nanofiber crosslinking is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine as a linker molecule between CNFs. The CNF hydrogels maintain their shape throughout the synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Precursor ion concentration variation allows for control over the final aerogel metal content through a direct ion reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in sol-gel methods. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metalized palladium porous structure.

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		<tr height="62">
			<td height="62" style="height:63px;width:295px;">0.5 mm platinum wire electrode</td>
			<td style="width:132px;">BASi</td>
			<td style="width:123px;">MW-4130</td>
			<td style="width:277px;">Used for auxillery electrode and separately for lacquer coating and use as a working electrode</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:295px;">1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td style="width:123px;">&#160;1892-57-5</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:295px;">2-(N-morpholino)ethanesulfonic acid (MES)</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td>117961-21-4&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Ag/AgCl (3M NaCl) Reference Electrode</td>
			<td style="width:132px;">BASi</td>
			<td style="width:123px;">MF-2052</td>
			<td></td>
		</tr>
		<tr height="83">
			<td height="83" style="height:84px;width:295px;">Carboxymethyl cellulose, TEMPO Cellulose Nanofibrils, Dry Powder</td>
			<td style="width:132px;">University of Maine Process Development Center</td>
			<td style="width:123px;">No 8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Ethanol, 200 proof</td>
			<td style="width:132px;">PHARMCO-AAPER</td>
			<td style="width:123px;">241000200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Ethylenediamine</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td style="width:123px;">&#160;107-15-3</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:295px;">Fourier-Transform Infrared (FTIR) Spectrometer, Frontier</td>
			<td style="width:132px;">Perkin Elmer</td>
			<td style="width:123px;">L1280044</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Hydrochloric Acid</td>
			<td style="width:132px;">CORCO</td>
			<td style="width:123px;">7647-01-0</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:295px;">Na2PdCl4</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td style="width:123px;">13820-40-1</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:295px;">NaBH4</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td style="width:123px;">16940-66-2</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:295px;">Pd(NH3)4Cl2</td>
			<td style="width:132px;">Sigma-Aldrich</td>
			<td style="width:123px;">13933-31-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Potentiostat</td>
			<td style="width:132px;">Biologic-USA</td>
			<td style="width:123px;">VMP-3</td>
			<td>Electrochemical analysis-EIS, CV</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:295px;">Scanning Electron Mciroscope (SEM) Helios 600 Nanolab</td>
			<td style="width:132px;">ThermoFisher Scientific</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:295px;">Supercritical Dryer</td>
			<td style="width:132px;">Leica</td>
			<td style="width:123px;">EM CPD300</td>
			<td>Aerogel supercritical drying with CO2</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Surface and Pore Analyzer</td>
			<td style="width:132px;">Quantachrome</td>
			<td style="width:123px;">NOVA 4000e</td>
			<td>Nitrogen gas adsorption</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">Thermal Gravimetric Analysis</td>
			<td style="width:132px;">TA instruments</td>
			<td style="width:123px;">TGA Q500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:295px;">Ultrasonic Cleaner</td>
			<td style="width:132px;">MTI</td>
			<td style="width:123px;">EQ-VGT-1860QTD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:295px;">XRD</td>
			<td style="width:132px;">PanAlytical</td>
			<td style="width:123px;">Empyrean</td>
			<td>X-ray diffractometry</td>
		</tr>
	</tbody>
</table>

synthesis method for cellulose nanofiber biotemplated palladium composite aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

The scheme to covalently crosslink cellulose nanofibers with EDC in the presence of ethylenediamine is depicted in Figure 1. EDC crosslinking results in an amide bond between a carboxyl and primary amine functional group. Given that the carboxymethyl cellulose nanofibers possess only carboxyl groups for crosslinking, the presence of a diamine linker molecule such as ethylenediamine is essential to covalently link two adjacent CNFs via two amide bonds. To conf...

Watch this Scientific Journal Video about Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels at JoVE.com

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...

This method using cellulose nanofiber biopolymer covalent hydrogels to achieve a palladium metal aerogel composite may be generalizable to a wide range of biopolymer templates and metals. This composite aerogel synthesis method uses cellulose nanofibers as a biotemplate to achieve control over both pallium metal nanostructure and macroscopic aerogel monolith shape. The shape control and mechanical integrity of biotemplated metal aerogels should facilitate applications for catalysis, energy storage, and sensing.This method can be applied to further develop biopolymer carbon metal templates and to achieve better control of three-dimensional nanostructures in composite aerogel materials. To prepare a cellulose nanofiber solution, first mix 1.5 grams of carboxymethyl cellulose nanofibers with 50 milliliters of deionized water. After shaking, vortex the solution for one minute, followed by a 24-hour incubation in a bath sonicator at ambient temperature to ensure complete mixing.The next morning, add 0.959 grams of EDC and 0.195 grams of MES buffer to 2.833 milliliters of deionized water. Then, adjust the final volume to 10 milliliters and a pH of 4.5 with one-molar hydrochloric acid and deionized water. Next, transfer 0.25 milliliters of the 3%cellulose nanofiber solution into each of six microfuge tubes, and sediment the nanofibers by centrifugation.Use a pipette to aspirate the excess water above the compacted nanofibers while avoiding contact with the top surface. Add one milliliter of the EDC and diamine crosslinking solution above the compacted cellulose nanofibers in each microfuge tube. Wait at least 24 hours for the crosslinking solution to diffuse through the gels to crosslink the cellulose nanofibers.Then, aspirate the crosslinking solution supernatant from the microfuge tubes, and immerse the microfuge tubes in one liter of deionized water for at least 24 hours with the caps open to remove any excess crosslinking solution from within the nanofiber hydrogels. The next day, add approximately 0.5 milliliters of one 3%cellulose nanofiber solution in deionized water to the sample stage of a Fourier-transform infrared spectrometer, and scan the percent transmittance for 650 to 4, 000 reciprocal centimeters. To prepare the palladium solution, vortex 10 milliliters of one-molar palladium ammonium chloride for 15 seconds before diluting the solution to one-milliliter volumes at one, 10, 50, 100, 500, and 1, 000-millimolar concentrations in deionized water.Next, add one milliliter of each dilution to the top of individual cellulose nanofiber hydrogel samples, and allow the palladium solutions to equilibrate within the hydrogels for 24 hours. The next day, prepare 60 milliliters of two-molar sodium borohydride and pipette 10 milliliters into each of six 15-milliliter conical tubes in a fume hood, and transfer the tubes of palladium equilibrated cellulose nanofiber hydrogels to the fume hood. Wearing the appropriate personal protection equipment, invert one microcentrifuge tube and gently tap the tube to remove the hydrogel, using flat tweezers to transfer the hydrogel into one of the tubes of sodium borohydride.After 24 hours, transfer each reduced hydrogel into a second 24-hour, 0.5-molar sodium borohydride reduction solution before rinsing the cellulose nanofiber-palladium composite gels in 50 milliliters of deionized water in new conical tubes. Exchange the deionized water after 12 hours, and allow the gels to rinse for at least an additional 12 hours. Then, use flat tweezers to transfer the rinsed cellulose nanofiber-palladium gels to successive 50-milliliter volumes of 25%50%75%and 100%ethanol solutions for at least six hours per solution.After the last solvent exchange, dry the hydrogels in a supercritical dryer with carbon dioxide, with a set point of 35 degrees Celsius and 1200 pounds per square inch. When the drying is complete, allow the chamber to equilibrate for at least 12 hours before opening the dryer for removal of the aerogels. To characterize the composite aerogels by scanning electron microscopy, use a razor blade to cut each gel into one-to two-millimeter-thick sections, and use carbon tape to fix the thin film sample onto a scanning electron microscope sample stub.Load the stub onto the microscope, and use an initial accelerating voltage of 15 kilovolts and a beam current of 2.7 to 5.4 picoamps to image the sample. To analyze the aerogels by x-ray diffractometry, place the cellulose nanofiber-palladium aerogel in a sample holder, and align the top of the aerogel with the top of the holder. Then, perform x-ray diffraction scans for diffraction angles two theta from five to 90 degrees at 45 kilovolts and 40 milliamps with copper K-alpha radiation, a two theta step size of 0130 degrees, and 20 seconds per step.For thermal gravimetric analysis, place an aerogel sample in the instrument crucible, and perform the analysis by flowing nitrogen gas at 60 milliliters per minute with heating at 10 degrees per minute from ambient temperature to 700 degrees Celsius. For nitrogen gas adsorption-desorption, degas the samples for 24 hours at room temperature before using nitrogen at minus 196 degrees Celsius as the test gas with equilibration times for adsorption and desorption of 60 and 120 seconds, respectively. For electrochemical characterization, immerse the aerogel samples in 0.5-molar sulfuric acid electrolyte for 24 hours before placing a lacquer-coated wire with a one-millimeter exposed tip in contact with the top surface of the aerogel at the bottom of the electrochemical vial.Then, use a three-electrode cell with a silver/silver chloride 0.5-millimeter-diameter platinum wire auxiliary counter electrode and a lacquer-coated 0.5-millimeter-diameter platinum working electrode to perform electrochemical impedance spectroscopy from one megahertz to one millihertz with a 10-millivolt sine wave and cyclic voltammetry using a voltage range of minus 0.2 to 1.2 volts with scan rates of 10, 25, 50, and 75 millivolts per second. Fourier-transform infrared spectroscopy can be performed as demonstrated to confirm cellulose nanofiber hydrogel crosslinking. Here, covalently crosslinked cellulose nanofiber hydrogels before and after equilibration across a range of palladium ammonium chloride or sodium palladium chloride concentrations are shown.Here, reduced cellulose nanofiber-palladium gels are shown before and after supercritical aerogel composite drying. In general, the aerogels present interconnected fibrillary ligaments with an increasing nanoparticle size, correlating with an increase in palladium solution concentration by scanning electron microscopy. X-ray diffractometry spectra for palladium and palladium hydride become more convoluted with increasing palladium synthesis concentration until the spectra are no longer distinguishable at 1, 000 millimolar, correlating with the increase in nanoparticle diameters observed by scanning electron microscopy.Thermogravimetric spectra analysis reveals an increasing metal content in the cellulose nanofiber-palladium composite aerogels as the synthesis palladium solution concentration increases. The physisorption data demonstrates a Type IV adsorption-desorption isotherm, indicating a mesoporous and macroporous structure, and Barrett-Joyner-Halenda pore size analysis indicates a decreasing frequency of mesopores as the aerogel palladium content increases. Electrochemical impedance spectroscopy spectra illustrate the low charge transfer resistance and double layer capacitance for the cellulose nanofiber-palladium composite aerogel.Further, cyclic voltammetry scans indicate hydrogen adsorption and desorption at potentials less than zero volts, as well as characteristic oxidation and reduction peaks for palladium greater than 0.5 volts. Remember to rinse the gels with incremental concentrations of water and ethanol as the osmotic swelling from large concentration differences may rupture the hydrogel. Incorporating other materials such as graphene and carbon nanotubes for composite biotemplates may be possible to achieve greater mechanical durability and conductivity of the aerogels.The use of cellulose nanofiber covalent hydrogels to achieve porous metal composite aerogels offers a synthesis route for other noble and transition metal materials in a variety of form factors. High concentrations of aqueous sodium borohydride results in the production of flammable hydrogen gas. It is important to electrochemically reduce the samples in a well-ventilated area, away from open flames.

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Research

JoVE Journal

Chemistry

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. The complexes were tested for catalytic activity in arylation and Suzuki-Miyaura reactions. For each reaction investigated, at least one of the four complexes successfully catalyzed the reaction.

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from ...

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of NixNb1-xO nanoparticles with different atomic compositions (x = 0.03, 0.08, 0.15, and 0.20) have been prepared by chemical precipitation. These NixNb1-xO catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The study revealed the sponge-like and fold-like appearance of Ni0.97Nb0.03O and Ni0.92Nb0.08O on the NiO surface, and the larger surface area of these NixNb1-xO catalysts, compared with the bulk NiO. Maximum surface area of 173 m2/g can be obtained for Ni0.92Nb0.08O catalysts. In addition, the catalytic hydroconversion of lignin-derived compounds using the synthesized Ni0.92Nb0.08O catalysts have been investigated.

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

A protocol for the synthesis of sponge-like and fold-like Ni1-xNbxO nanoparticles by chemical precipitation is presented.

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

A Salt-Templated Synthesis Method for Porous Platinum-based Macrobeams and Macrotubes

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.

A synthesis method to obtain porous platinum-based macrotubes and macrobeams with a square cross section through chemical reduction of insoluble salt-needle templates is presented.

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed ...

Localized Bathless Metal-Composite Plating via Electrostamping

Composite plating with particles embedded into the metal matrix can enhance the properties of the metal coating to make it more or less conductive, hard, durable, lubricated or fluorescent. However, it can be more challenging than metal plating, because the composite particles are either 1) not charged so they do not have a strong electrostatic attraction to the cathode, 2) are hygroscopic and are blocked by a hydration shell, or 3) too large to remain stagnate at the cathode while stirring. Here, we describe the details of a bathless plating method that involves anode and cathode nickel plates sandwiching an aqueous concentrated electrolyte paste containing large hygroscopic phosphorescent particles and a hydrophilic membrane. After applying a potential, the nickel metal is deposited around the stagnant phosphor particles, trapping them in the film. The composite coatings are characterized by optical microscopy for film roughness, thickness and composite surface loading. In addition, fluorescence spectroscopy can be used to quantify the illumination brightness of these films to assess the effects of various current densities, coating duration and phosphor loading.

Presented here is a protocol of bathless electroplating, where a stagnant metal salt paste containing composite particles are reduced to form metal composites at high loading. This method addresses the challenges faced by other common forms of electroplating (jet, brush, bath) of embedding composites particles into the metal matrix.

Composite plating with particles embedded into the metal matrix can enhance the properties of the metal coating to make it more or less conductive, hard, ...