Name: solvothermal synthesis of mil-96 and uio-66-nh2 on atomic layer deposited metal oxide coatings on fiber mats
Uploaded: 2018-06-13T14:45:00
Description: Watch this Scientific Journal Video about Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats at JoVE.com

The authors thank their collaborators at RTI International, US Army Natick Soldier RD&#38;E Center, and Edgewood Chemical and Biological Center. They also thank their funding source, the Defense Threat Reduction Agency.

1. Atomic Layer Deposition (ALD) of Al2O3 on Fiber Mats
<ol>
	<li>Place a 2.54 x 2.54 cm2 polypropylene fabric sample in the reactor boat (a thin, rigid, metal mesh holder). A schematic of the reactor is presented in Figure 2.</li>
	<li>Open the pressure gauge. Remove the clasp from the reactor cap. Turn on manual control in the LabView system. Close the carrier nitrogen and gate valve on the ALD reactor. Open the vent nitrogen.</li>
	<li>After removing the...

<ol>
	<li>Furukawa, H., Cordova, K. E., O'Keeffe, M., Yaghi, O. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Chemistry+and+Applications+of+Metal-Organic+Frameworks.">The Chemistry and Applications of Metal-Organic Frameworks.</a> Science (Washington, DC, U. S.). 341 (6149), 974 (2013).</li><li>Farha, O. 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=Metal-Organic+Framework+Materials+with+Ultrahigh+Surface+Areas:+Is+the+Sky+the+Limit?.">Metal-Organic Framework Materials with Ultrahigh Surface Areas: Is the Sky the Limit?.</a> Journal of the American Chemical Society. 134 (36), 15016-15021 (2012).</li><li>Bobbitt, N. 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Y., 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=Effective,+Facile,+and+Selective+Hydrolysis+of+the+Chemical+Warfare+Agent+VX+Using+Zr6-Based+Metal-Organic+Frameworks.">Effective, Facile, and Selective Hydrolysis of the Chemical Warfare Agent VX Using Zr6-Based Metal-Organic Frameworks.</a> Inorganic Chemistry. 54 (22), 10829-10833 (2015).</li><li>Zhou, H., Kitagawa, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal-Organic+Frameworks+(MOFs).">Metal-Organic Frameworks (MOFs).</a> Chemical Society Reviews. 43 (16), 5415-5418 (2014).</li><li>Qiu, M., Chen, C., Li, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+controllable+synthesis+of+Al-MIL-96+and+its+adsorption+of+nitrogenous+VOCs.">Rapid controllable synthesis of Al-MIL-96 and its adsorption of nitrogenous VOCs.</a> Catalysis Today. 258, 132-138 (2015).</li><li>Abid, H. R., Rada, Z. H., Shang, J., Wang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis,+characterization,+and+CO2+adsorption+of+three+metal-organic+frameworks+(MOFs):+MIL-53,+MIL-96,+and+amino-MIL-53.">Synthesis, characterization, and CO2 adsorption of three metal-organic frameworks (MOFs): MIL-53, MIL-96, and amino-MIL-53.</a> Polyhedron. 120, 103-111 (2016).</li><li>Lee, J. S., Jhung, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor-phase+adsorption+of+alkylaromatics+on+aluminum-trimesate+MIL-96:+An+unusual+increase+of+adsorption+capacity+with+temperature.">Vapor-phase adsorption of alkylaromatics on aluminum-trimesate MIL-96: An unusual increase of adsorption capacity with temperature.</a> Microporous Mesoporous Materials. 129 (1-2), 274-277 (2010).</li><li>Gil-San-Millan, R., 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=Chemical+Warfare+Agents+Detoxification+Properties+of+Zirconium+Metal-Organic+Frameworks+by+Synergistic+Incorporation+of+Nucleophilic+and+Basic+Sites.">Chemical Warfare Agents Detoxification Properties of Zirconium Metal-Organic Frameworks by Synergistic Incorporation of Nucleophilic and Basic Sites.</a> ACS Appl. Material Interfaces. 9 (28), 23967-23973 (2017).</li><li>Peterson, 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=Tailoring+the+Pore+Size+and+Functionality+of+UiO-Type+Metal-Organic+Frameworks+for+Optimal+Nerve+Agent+Destruction.">Tailoring the Pore Size and Functionality of UiO-Type Metal-Organic Frameworks for Optimal Nerve Agent Destruction.</a> Inorganic Chemistry. 54 (20), 9684-9686 (2015).</li><li>Katz, M. 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=Exploiting+parameter+space+in+MOFs:+a+20-fold+enhancement+of+phosphate-ester+hydrolysis+with+UiO-66-NH2.">Exploiting parameter space in MOFs: a 20-fold enhancement of phosphate-ester hydrolysis with UiO-66-NH2.</a> Chemical Science. 6 (4), 2286-2291 (2015).</li><li>Zhao, 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=Highly+Adsorptive,+MOF-Functionalized+Nonwoven+Fiber+Mats+for+Hazardous+Gas+Capture+Enabled+by+Atomic+Layer+Deposition.">Highly Adsorptive, MOF-Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition.</a> Advanced Materials Interface. 1 (4), 1400040 (2014).</li><li>Peterson, G. W., Lu, A. X., Epps, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+the+Morphology+and+Activity+of+Electrospun+Polystyrene/+UiO-66-NH2+Metal-Organic+Framework+Composites+to+Enhance+Chemical+Warfare+Agent+Removal.">Tuning the Morphology and Activity of Electrospun Polystyrene/ UiO-66-NH2 Metal-Organic Framework Composites to Enhance Chemical Warfare Agent Removal.</a> ACS Applied Materials &amp; Interfaces. 9 (37), 32248-32254 (2017).</li><li>Lee, D. T., Zhao, J., Peterson, G. W., Parsons, G. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catalytic+'+MOF-Cloth+'+Formed+via+Directed+Supramolecular+Assembly+of+UiO-66-NH+2+Crystals+on+Atomic+Layer+Deposition-+Coated+Textiles+for+Rapid+Degradation+of+Chemical+Warfare+Agent+Simulants.">Catalytic ' MOF-Cloth ' Formed via Directed Supramolecular Assembly of UiO-66-NH 2 Crystals on Atomic Layer Deposition- Coated Textiles for Rapid Degradation of Chemical Warfare Agent Simulants.</a> Chemistry of Materials. 29 (11), 4894-4903 (2017).</li><li>L&#243;pez-maya, E., 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=Textile+/+Metal+-+Organic-Framework+Composites+as+Self-Detoxifying+Filters+for+Chemical-Warfare+Agents.">Textile / Metal - Organic-Framework Composites as Self-Detoxifying Filters for Chemical-Warfare Agents.</a> Angewandte Chemie International Edition. 54 (23), 6790-6794 (2015).</li><li>Zhao, 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=Conformal+and+highly+adsorptive+metal-organic+framework+thin+films+via+layer-by-layer+growth+on+ALD-coated+fiber+mats.">Conformal and highly adsorptive metal-organic framework thin films via layer-by-layer growth on ALD-coated fiber mats.</a> Journal of Materials Chemistry. A. 3 (4), 1458-1464 (2015).</li><li>Lemaire, P. 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=Copper+Benzenetricarboxylate+Metal-Organic+Framework+Nucleation+Mechanisms+on+Metal+Oxide+Powders+and+Thin+Films+formed+by+Atomic+Layer+Deposition.">Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.</a> ACS Applied Materials &amp; Interfaces. 8 (14), 9514-9522 (2016).</li><li>Zacher, D., Baunemann, A., Hermes, S., Fischer, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deposition+of+microcrystalline+[Cu3(btc)2]+and+[Zn2(bdc)2(dabco)]+at+alumina+and+silica+surfaces+modified+with+patterned+self+assembled+organic+monolayers:+evidence+of+surface+selective+and+oriented+growth.">Deposition of microcrystalline [Cu3(btc)2] and [Zn2(bdc)2(dabco)] at alumina and silica surfaces modified with patterned self assembled organic monolayers: evidence of surface selective and oriented growth.</a> Journal of Materials Chemistry. 17 (27), 2785-2792 (2007).</li><li>Parsons, G. N., 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=Mechanisms+and+reactions+during+atomic+layer+deposition+on+polymers.">Mechanisms and reactions during atomic layer deposition on polymers.</a> Coordination Chemisty Reviews. 257 (23-24), 3323-3331 (2013).</li><li>Zhao, 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=Facile+Conversion+of+Hydroxy+Double+Salts+to+Metal-Organic+Frameworks+Using+Metal+Oxide+Particles+and+Atomic+Layer+Deposition+Thin-Film+Templates.">Facile Conversion of Hydroxy Double Salts to Metal-Organic Frameworks Using Metal Oxide Particles and Atomic Layer Deposition Thin-Film Templates.</a> Journal of the American Chemical Soceity. 137 (43), 13756-13759 (2015).</li><li>Zhao, 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=Ultra-Fast+Degradation+of+Chemical+Warfare+Agents+Using+MOF+-+Nanofiber+Kebabs.">Ultra-Fast Degradation of Chemical Warfare Agents Using MOF - Nanofiber Kebabs.</a> Angewandte Chemie International Edition. 55 (42), 13224-13228 (2016).</li><li>Lee, D., Zhao, J., Oldham, C., Peterson, G., Parsons, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=UiO-66-NH2+Metal–Organic+Framework+(MOF)+Nucleation+on+TiO2,+ZnO,+and+Al2O3+Atomic+Layer+Deposition-Treated+Polymer+Fibers:+Role+of+Metal+Oxide+on+MOF+Growth+and+Catalytic+Hydrolysis+of+Chemical+Warfare+Agent+Simulants.">UiO-66-NH2 Metal–Organic Framework (MOF) Nucleation on TiO2, ZnO, and Al2O3 Atomic Layer Deposition-Treated Polymer Fibers: Role of Metal Oxide on MOF Growth and Catalytic Hydrolysis of Chemical Warfare Agent Simulants.</a> ACS Applied Materials &amp; Interfaces. 9 (51), 44847-44855 (2017).</li><li>Spagnola, J. 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The ALD coating strongly influences the adhesion and loading of the MOF. First, depending on the type of substrate and ALD precursor, the ALD layer can either form a distinct outer shell around the fiber, or diffuse into the fiber to create a gradual transition to the metal oxide coating20. The hard shell has been observed on cotton and nylon substrates, while diffusive layers can be observed in polypropylene under proper conditions. Second, the diffusion into the fiber can also be controlled by v...

Metal-organic frameworks are crystalline structures consisting of reactive metal cluster centers bridged by organic molecule linkers to provide large porosities and surface areas. Their structure, porosity, and functionality can be designed by choosing appropriate clusters and linkers, leading to surface areas as high as&#160;7,000 m2/gMOF1,2. Their high porosity and surface area have made MOFs diversely applicable in adsorption, separation, and heterogeneous catalysis in fields ranging from energy production to environmental concerns to biological processes1,3,4,5,6.
Numerous MOFs have proven successful in selectively adsorbing volatile organic compounds and greenhouse gases or to catalytically degrade chemicals that may prove harmful to human health or the environment. In particular, MIL-96 (Al) has shown to selectively adsorb nitrogenous volatile organic compounds (VOCs) due to the availability of lone pair electrons in the nitrogen groups to coordinate with the weak Lewis acid Al present in the metal clusters7. MIL-96 has also been shown to adsorb gases such as CO2, p-xylene, and m-xylene8,9. MOF adsorption selectivity is dependent on both the Lewis acid of the metal cluster, as well as pore size. The pore size of MIL-96 increases with temperature, resulting in increased adsorption capacity of trimethylbenzene with increased temperature, and presents the opportunity of tuning selectivity with adsorption temperature9.
The second MOF of focus here, UiO-66-NH2 has been shown to catalytically degrade chemical warfare agents (CWAs) and simulants. The amine group on the linker provides a synergistic effect in degrading nerve agents, while preventing agent degradation products from binding irreversibly to the zirconium clusters and poisoning the MOF10. UiO-66-NH2 has catalytically hydrolyzed dimethyl p-nitrophenylphosphate (DMNP) with a half-life as short as 0.7 minutes in buffered conditions, nearly 20 times faster than its base MOF UiO-6611,12.
While these adsorption and catalytic properties are promising, the physical form of the MOFs, primarily bulk powder, can be difficult to incorporate into platforms for gas capture and filtration without adding significant bulk, clogging pores, or reducing MOF flexibility. An alternative is to create MOF functionalized fabrics. MOFs have been incorporated into fabrics in myriad ways, including electrospinning MOF powder/polymer slurries, adhesive mixes, spray coating, solvothermal growth, microwave syntheses, and a layer-by-layer growth method13,14,15,16,17,18. Of these, electrospinning and polymer adhesives can result in blocked functional sites on the MOF as they are encapsulated in the polymer, significantly decreasing adsorption capacity and reactivity. Additionally, many of these techniques fail to create conformal coatings on the fibers due to line of sight difficulties or poor adhesion/nucleation and the reliance on purely electrostatic interactions. An alternative method is to first coat the fabric with a metal oxide to allow for stronger surface interactions with the MOF18,19.
One method of metal oxide deposition is atomic layer deposition (ALD). ALD is a technique for depositing conformal thin films, controllable to the atomic scale. The process utilizes two half reactions that occur only at the surface of the substrate to be coated. The first step is to dose a metal containing precursor, which reacts with hydroxyls on the surface, leaving a metallated surface while excess reactant is purged from the system. The second reactant is an oxygen-containing reactant, typically water, which reacts with the metal sites to form a metal oxide. Again, excess water and any reaction products are purged from the system. These alternating doses and purges can be repeated until the desired film thickness is achieved (Figure 1). Atomic layer deposition is particularly useful because the small-scale vapor phase precursors allow for conformal films on every surface of substrates with complex topology, such as fiber mats. Additionally, for polymers such as polypropylene, the ALD conditions can allow the coating to diffuse into the fiber surface, providing a strong anchor for future MOF growth20.
The metal oxide coating allows for increased nucleation sites on the fibers during traditional solvothermal synthesis by increasing functional groups and roughness18,20. Our group has previously shown the ALD metal oxide base layer is effective for UiO-6X, HKUST-1, and other syntheses through various routes of solvothermal, layer-by-layer, and hydroxy-double salt conversion methods13,17,18,21,22,23. Here we demonstrate two synthesis types. The MIL materials are formed by converting the Al2O3 ALD coating directly to MOF by diffusion of the organic linker. By submerging an Al2O3 ALD coated fiber mat in trimesic acid solution and heating, the organic linker diffuses into the metal oxide coating to form MIL-96. This results in a strongly adhered, conformal MOF coating on every fiber surface. The second synthesis approach calls for typical UiO-66-NH2 hydrothermal synthesis using metal and organic precursors, but adds a metal oxide coated fiber mat on which the MOF nucleates. For both synthesis approaches, the resulting products consist of conformal thin films of MOF crystals strongly adhered to the supporting fabric. In the case of MIL-96, these can be incorporated into filters for adsorption of VOCs or greenhouse gases. For UiO-66-NH2 these fabrics can be easily incorporated into lightweight protective clothing for military personnel, first responders, and civilians for continuous defense against CWA attacks.

<table border="0" cellpadding="0" cellspacing="0" width="625">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">trimethylaluminum</td>
			<td style="width:123px;">Strem Chemicals</td>
			<td style="width:119px;">93-1360</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">home-built ALD reactor</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">nitrogen cylinder</td>
			<td style="width:123px;">Arc3</td>
			<td style="width:119px;">UN1066</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">trimesic acid</td>
			<td style="width:123px;">Sigma-Aldrich</td>
			<td style="width:119px;">482749-500G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ethanol</td>
			<td style="width:123px;">Koptec</td>
			<td style="width:119px;">V1001</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">teflon lined autoclave</td>
			<td style="width:123px;">PARR Instrument Company</td>
			<td style="width:119px;">4760-1211</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isotemp furnace</td>
			<td style="width:123px;">Fisher Scientific</td>
			<td style="width:119px;">F47925</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Zirconium (IV) chloride</td>
			<td style="width:123px;">Alfa Aesar</td>
			<td style="width:119px;">12104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">2-aminoterephthalic acid</td>
			<td style="width:123px;">Acros Organics</td>
			<td style="width:119px;">278031000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">N,N-dimethylformamide</td>
			<td style="width:123px;">Fisher Scientific</td>
			<td style="width:119px;">D119-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hydrochloric Acid</td>
			<td style="width:123px;">Fisher Scientific</td>
			<td style="width:119px;">A481-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polypropylene fiber mats</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polyamide fiber mats</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

solvothermal synthesis of mil-96 and uio-66-nh2 on atomic layer deposited metal oxide coatings on fiber mats

Metal-organic frameworks (MOFs), which contain reactive metal clusters and organic ligands allowing for large porosities and surface areas, have proven effective in gas adsorption, separations, and catalysis. MOFs are most commonly synthesized as bulk powder, requiring additional processes to adhere them to functional devices and fabrics that risk decreasing the powder porosity and adsorption capacity. Here, we demonstrate a method of first coating fabrics with metal oxide films using atomic layer deposition (ALD). This process creates conformal films of controllable thickness on each fiber, while providing a more reactive surface for MOF nucleation. By submerging the ALD coated fabric in solution during solvothermal MOF synthesis, the MOFs create a conformal, well-adhered coating on the fibers, resulting in a MOF-functionalized fabric, without additional adhesion materials that may block MOF pores and functional sites. Here we demonstrate two solvothermal synthesis methods. First, we form a MIL-96(Al) layer on polypropylene fibers using synthetic conditions that convert the metal oxide to MOF. Using initial inorganic films of varying thicknesses, diffusion of the organic linker into the inorganic allows us to control the extent of MOF loading on the fabric. Second, we perform a solvothermal synthesis of UiO-66-NH2 in which the MOF nucleates on the conformal metal oxide coating on polyamide-6 (PA-6) fibers, thereby producing a uniform and conformal thin film of MOF on the fabric. The resulting materials can be directly incorporated into filter devices or protective clothing and eliminate the maladroit qualities of loose powder.

To describe the MOF/fabric materials, we delineate two terms related to measured surface area. First, projected surface area, cm2projected, refers to the macroscopic size of the fabric swatch as measured with a ruler, i.e., the area of the sample&#39;s projected shadow. The second surface area of interest is the BET surface area, calculated from a nitrogen isotherm obtained at 77 K. These values are given in units of m2/gFabric, m2...

Watch this Scientific Journal Video about Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats at JoVE.com

Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats

Metal-organic frameworks are effective in gas storage and heterogeneous catalysis, but typical synthesis methods result in loose powders that are difficult to incorporate into smart materials. We demonstrate a method of first coating fabrics with ALD metal oxides, resulting in conformal films of MOF on the fabrics during solvothermal synthesis.

Solvothermal Synthesis of MIL-96 and UiO-66-NH2 on Atomic Layer Deposited Metal Oxide Coatings on Fiber Mats

Metal-organic frameworks (MOFs), which contain reactive metal clusters and organic ligands allowing for large porosities and surface areas, have proven ...

This method can help answer key questions in the field of metal organic frameworks such as the nature of surface nucleation and MOF adhesion. The main advantage of this technique is that it produces MOF films on fabric during the MOF synthesis rather than requiring additional processing steps to adhere MOF to the fiber. Demonstrating the procedure will be Dennis Lee, a grad student from my laboratory.First, place a PA-6 fabric sample in a reactor boat. Open the pressure gauge of the ALD reactor and remove the clasp from the reactor cap. Next, turn on manual control in the lab view system.Close the carrier nitrogen and gate valve on the ALD reactor. Then open the vent nitrogen. The reactor will open and the cap will fall off.After removing the reactor cap, load the fabric sample into the ALD reactor. Replace the reactor cap. Then open the gate valve.Following this, open the carrier nitrogen and close the vent. Then turn off manual control. Load the recipe for titanium oxide on fabrics.Set the recipe to run 300 cycles. Next, set the mass flow controller to 20 cubic feet per minute and the furnace temperature to 90 degrees Celsius. Open the manual valve to the titanium tetrachloride and water.Close the pressure gauge and replace the clasp on the reactor cap. Then press start on the interface. Upon completion of the recipe, open the pressure gauge.Remove the clasp from the reactor cap. Then turn on manual control in the system. Following this, close the carrier nitrogen and gate valve on the ALD reactor.Then open the vent nitrogen. The reactor will open and the cap will fall off. Remove the sample boat.Reseal the reactor. Add 0.0878 grams of trimesic acid to an 80 milliliter glass beaker. Add 12 milliliters of water and 12 milliliters of ethanol to the beaker.Then add a magnetic stir bar to the solution and stir until the trimesic acid is fully dissolved. Next, place the solution in a Teflon-lined pressure vessel. Add previously prepared aluminum oxide-coded polypropylene to the solution and prop the fabric on a mesh support so it does not lie flat against the bottom of the vessel.Following this, seal the pressure vessel and place it in the furnace at 110 degrees Celsius for 24 hours. Add 0.08 grams of zirconium chloride to a 20 milliliter glass scintillation vial. Add 20 milliliters of DMF to the zirconium chloride in five milliliter increments.Cap the vial between increments and allow the fumes to dissipate. Next, sonicate the solution for one minute. Add 0.062 grams of 2-aminoterephthalic acid and a magnetic stir to the vial.Stir the solution for five minutes. After stirring, add 25 microliters of deionized water to the vial. Then add 1.33 milliliters of concentrated hydrochloric acid to the vial.Now submerge the titanium dioxide ALD-coded fabric swatch in the solution and cap the vial. Finally, place the sample in the furnace at 85 degrees Celsius for 24 hours. Scanning electron microscopy showed conformal MOF crystal thin films on all fibers resembling a cobblestone pattern.When the aluminum oxide was reduced, the film began to break apart as the MOF formed resulting in a patchy coding. A bare polypropylene sample was exposed to MIL-96 synthesis conditions, but XRD showed no detectable MOF on the fibers. Cross-sectional images revealed the 500 cycle aluminum oxide base layer completely reacted while a fraction of the aluminum oxide base layer remained for the 1, 000 and 2, 000 cycle samples.Cross-sections of the aluminum oxide ALD-coded polypropylene are shown here. Electron dispersion spectroscopy images of the cross-section revealed the carbon-based polypropylene core and predominantly aluminum oxide shell. XRD patterns of the MOF-coded fabric matching the simulated PXRD pattern of MIL-96 are shown here.Following solvothermal MOF synthesis, XRD patterns revealed UIO-66-amine was present on the fibers. SEM images showed flaky MOF codings on the 50 degree Celsius samples, dense MOF codings on the 90 degree Celsius samples, and sparse MOF codings on the 200 degree Celsius samples. An uncoded PA-6 sample was exposed to UIO-66-amine synthesis conditions resulting in a relatively sparse MOF coding.After watching this video, you should have a good understanding of how to produce conformal MOF films on ALD-coded substrates.

solvothermal-synthesis-mil-96-uio-66-nh2-on-atomic-layer-deposited

Research

JoVE Journal

Chemistry

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics.

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Here we present a protocol for synthesizing Zn1-xMgxO/Cu2O heterojunctions in open-air at low temperature via atmospheric pressure spatial atomic layer deposition (AP-SALD) of Zn1-xMgxO on cuprous oxide. Such high quality conformal metal oxides can be grown on a variety of substrates including plastics by this cheap and scalable method.

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

The use of nanoprobes such as gold, silver, silica or iron-oxide nanoparticles as detection reagents in bioanalytical assays can enable high sensitivity and convenient colorimetric readout. However, high densities of nanoparticles are typically needed for detection. The available synthesis-based enhancement protocols are either limited to gold and silver nanoparticles or rely on precise enzymatic control and optimization. Here, we present a protocol to enhance the colorimetric readout of gold, silver, silica, and iron oxide nanoprobes. It was observed that the colorimetric signal can be improved by up to a 10000-fold factor. The basis for such signal enhancement strategies is the chemical reduction of Au3+ to Au0. There are several chemical reactions that enable the reduction of Au3+ to Au0. In the protocol, Good&#39;s buffers and H2O2 are used and it is possible to favor the deposition of Au0 onto the surface of existing nanoprobes, in detriment of the formation of new gold nanoparticles. The protocol consists of the incubation of the microarray with a solution consisting of chloroauric acid and H2O2 in 2-(N-morpholino)ethanesulfonic acid pH 6 buffer following the nanoprobe-based detection assay. The enhancement solution can be applied to paper and glass-based sensors. Moreover, it can be used in commercially available immunoassays as demonstrated by the application of the method to a commercial allergen microarray. The signal development requires less than 5 min of incubation with the enhancement solution and the readout can be assessed by naked eye or low-end image acquisition devices such as a table-top scanner or a digital camera.

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

In this work, a protocol for signal enhancement of nanoprobe-based biosensing is presented. The protocol is based on the reduction of chloroauric acid onto the surface of existing nanoprobes that consist of gold, silver, silica or iron-oxide nanoparticles.

The use of nanoprobes such as gold, silver, silica or iron-oxide nanoparticles as detection reagents in bioanalytical assays can enable high sensitivity ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...

Niobium Oxide Films Deposited by Reactive Sputtering: Effect of Oxygen Flow Rate

Reactive sputtering is a versatile technique used to form compact films with excellent homogeneity. In addition, it allows easy control over deposition parameters such as gas flow rate that results in changes on composition and thus in the film required properties. In this report, reactive sputtering is used to deposit niobium oxide films. A niobium target is used as metal source and different oxygen flow rates to deposit niobium oxide films. The oxygen flow rate was changed from 3 to 10 sccm. The films deposited under low oxygen flow rates show higher electrical conductivity and provide better perovskite solar cells when used as electron transport layer.

Here, we present a protocol for niobium oxide films deposition by reactive sputtering with different oxygen flow rates for use as an electron transport layer in perovskite solar cells.

Reactive sputtering is a versatile technique used to form compact films with excellent homogeneity. In addition, it allows easy control over deposition ...

The Effect of Anodization Parameters on the Aluminum Oxide Dielectric Layer of Thin-Film Transistors

Aluminum-oxide (Al2O3) is a low cost, easily processable and high dielectric constant insulating material that is particularly appropriate for use as the dielectric layer of thin-film transistors (TFTs). Growth of aluminum-oxide layers from anodization of metallic aluminum films is greatly advantageous when compared to sophisticated processes such as atomic layer deposition (ALD) or deposition methods that demand relatively high temperatures (above 300 &#176;C) such as aqueous combustion or spray-pyrolysis. However, the electrical properties of the transistors are highly dependent on the presence of defects and localized states at the semiconductor/dielectric interface, which are strongly affected by the manufacturing parameters of the anodized dielectric layer. To determine how several fabrication parameters influence the device performance without performing all possible combination of factors, we used a reduced factorial analysis based on a Plackett-Burman design of experiments (DOE). The choice of this DOE permits the use of only 12 experimental runs of combinations of factors (instead of all 256 possibilities) to obtain the optimized device performance. The ranking of the factors by the effect on device responses such as the TFT mobility is possible by applying analysis of variance (ANOVA) to the obtained results.

Anodization parameters for growth of the aluminum-oxide dielectric layer of zinc-oxide thin-film transistors (TFTs) are varied to determine the effects on the electrical parameter responses. Analysis of variance (ANOVA) is applied to a Plackett-Burman design of experiments (DOE) to determine the manufacturing conditions that result in optimized device performance.

Aluminum-oxide (Al2O3) is a low cost, easily processable and high dielectric constant insulating material that is particularly appropriate for use as the ...