Name: Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe CdS Nanorods (Video) | JoVE Journal
Uploaded: 2016-02-11T15:00:00.000+00:00
Duration: 5 min 41 s
Description: Learn photochemical oxidative growth of iridium oxide nanoparticles on CdSe@CdS nanorods for enhanced hydrogen production. This method improves cadmium sulfide stability using photochemical oxidation techniques.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This research was supported by the I-CORE Program of the Planning and Budgeting Committee and The Israel Science Foundation (Grant No. 152/11). We thank the Schulich Faculty of Chemistry and the Technion - Israel Institute of Technology for the renovated laboratory and startup package. We also thank the Royal Society of Chemistry for permission in adapting materials from http://dx.doi.org/10.1039/C4TA06164K for use in this manuscript. Dr. Kalisman thanks the Schulich postdoctoral fellowship for their support. We thank Dr. Yaron Kauffmann for his assistance with HR-TEM and HAADF as well as Dr. Kamira Weinfeld for her assistance with XPS characterization.

1. Synthesis of Quantum Dots21
<ol>
	<li>Preparation of TOP:Se Precursor
	<ol>
		<li>Combine 58 mg of Se powder with 0.360 g of Tri-n-octylphosphine (TOP) in a vial with a septum.</li>
		<li>Sonicate the TOP:Se mixture until it is clear with no solids.</li>
	</ol>
	</li>
	<li>Synthesis of CdSe
	<ol>
		<li>Combine 3.0 g trioctylphosphine oxide (TOPO), 280 mg n-octadecylphosphonic acid (ODPA), and 60 mg CdO with a 3 mm x 8 mm cylindrical stir bar in a 25 ml 3-neck round bottom flask equipped with a thermocouple (inserted in a custom glass adapter), a reflux condenser with a T-joint (center neck), and a rubber septum. Assemble all glass-to-glass joints with high temperature vacuum grease. Connect the T-joint to a Schlenk line on one end that can be switched between a clean inert gas and vacuum, while connecting the other end to a bubbler. 
		Caution: CdO is very toxic and should be weighed and added to the round bottom flask inside an enclosed environment such as a glovebox.</li>
		<li>Place the round bottom flask apparatus in a heating mantle, and purge with inert gas.</li>
		<li>Heat the solids in the round bottom flask to 150 &#176;C, making sure to start stirring vigorously once the compounds melt (around 60-80 &#176;C). In order to avoid overshooting the target temperature, heat to 100 &#176;C and then 150 &#176;C once the heating rate slows down or stabilizes.</li>
		<li>Degas the mixture under vacuum (at 150 &#176;C) for at least 1 hr while still stirring. Make sure the T-joint is not open to the bubbler or the oil will get sucked into the flask and Schlenk line. When moving from gas to vacuum be careful to transition slowly to avoid more than a rolling boil.</li>
		<li>Refill the flask with inert gas (and continue to flow gas over the sample) and increase the temperature to 350 &#176;C. The solution should turn clear as it heats up, and excess solids on the flask wall can be collected by careful swirling of the flask.</li>
		<li>Inject 1.5 g of TOP into the flask through the septum. Allow the solution temperature to stabilize before proceeding. 
		Note: Try to minimize the amount of air/moisture injected by keeping the TOP in a septa vial under inert atmosphere, and injecting it as quickly as possible.</li>
		<li>Inject all of the TOP:Se mixture (prepared in section 1.1) into the flask through the septum, using a wide needle to inject the TOP:Se as quickly and uniformly as possible.</li>
		<li>Let the reaction proceed for the desired time, and remove from the heating mantle.
		<ol>
			<li>For very small seeds remove from heat just before injecting. For larger seeds remove the flask from heat immediately after injecting TOP:Se or after waiting up to 3 min. Longer wait result in larger seeds.</li>
		</ol>
		</li>
		<li>Let the reaction cool to approximately 100 &#176;C and inject approximately 5 ml of degassed toluene. Transfer the solution to a vial under inert atmosphere for cleaning. 
		Note: To simplify this process 10 ml of toluene can be placed in a 20 ml vial with a septa under constant flow of inert gas. Use approximately half of this toluene to inject into the cooling mixture, and then transfer the cooled mixture back into this vial.</li>
		<li>Cleaning of seeds
		<ol>
			<li>Put the solution in a 50 ml centrifuge tube.</li>
			<li>Add methanol (approximately 5 ml) to precipitate out the seeds from the toluene mixture.</li>
			<li>Centrifuge at 3,400 x g for 5 min.</li>
			<li>Decant clear supernatant and re-dissolve the pellet in toluene (5-10 ml).</li>
			<li>Repeat steps 1.2.10.2 through 1.2.10.4 at least three times total.</li>
		</ol>
		</li>
		<li>Dilute a small aliquot of the seeds in toluene in order to measure Ultraviolet-Visible (UV-Vis) absorbance between 350-800 nm. Use the peaks to determine the concentration and size of the CdSe seeds as described in the literature22.</li>
	</ol>
	</li>
</ol>
2. Synthesis of Seeded Rods 21
<ol>
	<li>Preparation of TOP:S Precursor
	<ol>
		<li>Combine 1.2 g of S with 15 g of TOP in a vial with a stir bar.</li>
		<li>Stir until clear with no solids (usually at least 24 hr).</li>
		<li>Measure 0.62 g of this mixture into a vial with a septum.</li>
	</ol>
	</li>
	<li>Preparation of TOP:CdSe Precursor
	<ol>
		<li>Measure the appropriate volume of CdSe seeds from step 1 (based on UV-Vis peak) into a vial with a septum. 
		Note: For a calculated concentration of 5x10-5 with 2.25 nm seeds (both values calculated from the UV-Vis spectra22), use 300 &#181;l of solution.</li>
		<li>Evaporate the toluene using a vacuum line until the seeds are dry. Do not leave under vacuum for more than 5-10 min once dry, as this can degrade the quality of the seeds.</li>
		<li>Re-dissolve all of the dried seeds in 0.5 g of TOP.</li>
	</ol>
	</li>
	<li>Synthesis of CdSe@Cds
	<ol>
		<li>Combine 60 mg propylphosphonic acid (PPA), 3.35 g TOPO, 1.080 g ODPA, and 230 mg CdO with a 3 mm x 8 mm cylindrical stir bar in a 25 ml 3-neck round bottom flask equipped with a thermocouple (inserted in a custom glass adapter), a reflux condenser with a T-joint (center neck), and a rubber septum. Assemble all glass-to-glass joints with high temperature vacuum grease. Connect the T-joint to a Schlenk line on one end that can be switched between a clean inert gas and vacuum, while connecting the other end to a bubbler. 
		Caution: CdO is very toxic and should be weighed and added to the round bottom inside an enclosed environment, such as a glovebox. PPA is regulated in some countries and can be replaced by butylphosphonic acid (BPA, 72 mg) or hexylphosphonic acid (HPA, 80 mg), though BPA and HPA usually result in shorter rods.</li>
		<li>Place the round bottom flask apparatus in a heating mantle, and purge with inert gas.</li>
		<li>Heat the solids in the round bottom flask to 120 &#176;C, making sure to start stirring vigorously once the compounds melt (around 60-80 &#176;C). In order to avoid overshooting the target temperature, heat to 90 &#176;C and then 120 &#176;C once the heating rate slows down or stabilizes.</li>
		<li>Degas the mixture under vacuum (at 120 &#176;C) for at least &#189; hr while still stirring.
		<ol>
			<li>Make sure the T-joint is not open to the bubbler or the oil will get sucked into the flask and Schlenk line. When moving from gas to vacuum be careful to transition slowly to avoid more than a rolling boil. Use a cold trap with liquid nitrogen (LN2) for a better vacuum.</li>
		</ol>
		</li>
		<li>Refill the flask with inert gas (and continue to flow gas over the sample) and increase the temperature to 320 &#176;C. The solution should turn clear as it heats up, and excess solids on the flask wall can be collected by careful swirling of the flask.</li>
		<li>Cool back down to 120 &#176;C and degas under vacuum as in step 1.2.4.</li>
		<li>Refill and reheat the flask as in step 1.2.5.</li>
		<li>Inject 1.5 g of TOP into the flask through the septum. Allow the solution temperature to stabilize at 340 &#176;C before proceeding. 
		Note: Try to minimize the amount of air/moisture injected by keeping the TOP in a septa vial under inert atmosphere, and injecting it as quickly as possible.</li>
		<li>Inject the TOP:S mixture into the flask through the septum, using a wide needle to inject the TOP:S as quickly and uniformly as possible. Start a timer.</li>
		<li>Exactly 20 sec after injecting the TOP:S, inject the TOP:CdSe mixture into the flask through the septum, using a wide needle to inject the TOP:CdSe as quickly and uniformly as possible. 
		Note: The temperature should have dropped to below 330 &#176;C by this point due to the addition of RT TOP solutions.</li>
		<li>Set the temperature to 320 &#176;C and let the reaction proceed for the desired time (8-15 min), and remove from the heating mantle.</li>
		<li>Let the reaction cool away from the heating mantle and inject approximately 5 ml of degassed toluene when the temperature reaches approximately 100 &#176;C. Transfer the solution to a vial under inert atmosphere for cleaning. 
		Note: To simplify this process 10 ml of toluene can be placed in a 20 ml vial with a septa under constant flow of inert gas. Use approximately half of this toluene to inject into the cooling mixture, and then transfer the cooled mixture back into this vial.</li>
		<li>Cleaning of rods
		<ol>
			<li>Put the solution in a 50 ml centrifuge tube.</li>
			<li>Add methanol (approximately 5 ml) to precipitate out the seeds from the toluene mixture.</li>
			<li>Centrifuge at 3,400 x g for 5 min.</li>
			<li>Decant clear supernatant and re-dissolve the pellet in approximately 10 ml hexane.</li>
			<li>Add 1-2 ml each of n-octylamine and nonanoic acid to the solution. The solution should be transparent.</li>
			<li>Add 5 ml methanol and centrifuge for 5 min at 3,400 x g.</li>
			<li>Repeat steps 2.3.13.4 through 2.3.13.6 at least twice more.</li>
			<li>Re-dissolve pellet in 10 ml of toluene. If the pellet does not easily dissolve, more cleaning steps are likely needed, in which case repeat steps 2.3.13.4 through 2.3.13.6.</li>
			<li>Add approximately 7 ml of IPA, 1 ml at a time, until the solution is slightly cloudy even when mixed.</li>
			<li>Centrifuge for 30 min at 2,200 x g in order to separate longer rods from everything else.</li>
			<li>Re-dissolve pellet in 10-15 ml of toluene.</li>
		</ol>
		</li>
		<li>Dilute a small aliquot of the seeds in toluene in order to measure UV-Vis absorbance and/or photoluminescence (PL) of the rods. 
		Note: Any aliquot volume is acceptable as long as the dilution factor is known, however, a typical dilution factor would be 20. For PL, the absorption should be at or below 0.1 at the chosen excitation wavelength (typically use 450 nm).&#160;</li>
	</ol>
	</li>
</ol>
3. Transfer of Seeded Rods to Aqueous Solution
<ol>
	<li>Preparation of Methanol Solution
	<ol>
		<li>Pour approximately 10 ml of methanol into a centrifuge tube.</li>
		<li>Add approximately 250 mg mercaptoundecanoic acid (MUA) and 400 mg tetramethylammonium hydroxide (TMAH).</li>
		<li>Vortex or let sit until all solids fully dissolved.</li>
	</ol>
	</li>
	<li>Ligand Exchange
	<ol>
		<li>Add methanol (5-10 ml, or enough to precipitate the rods) to &#188; to &#189; of rods synthesized from step 2 in a centrifuge tube. 
		Note: The volume of rods used will be dependent on the amount of toluene used to dissolve the rods for storage. If 10-15 ml are used as suggested in step 2.3.13.11, then 3-6 ml of the rod solution should be appropriate.</li>
		<li>Centrifuge at 3,400 x g for 5 min.</li>
		<li>Decant the clear supernatant.</li>
		<li>Add all of the methanol solution from section 3.1 to the pellet.</li>
		<li>Vortex or shake by hand to fully dissolve. Allow the solution to sit at least 1 hr to allow maximum ligand exchange to occur. 
		Note: The solution should be allowed to sit for at least 1 hr even if it appears to dissolve immediately and completely</li>
		<li>Separate the solution into two halves in two centrifuge tubes. 
		Note: Save the centrifuge tube used for step 3.1 and transfer half of the solution into there.</li>
		<li>Add 20 ml of toluene to each half. If there is a phase separation between the alcohol and toluene add methanol drop wise until the phases recombine.</li>
		<li>Centrifuge at 7,700 x g for 15 min.</li>
		<li>Very carefully decant the clear supernatant from pellet.</li>
		<li>Invert the centrifuge tube carefully in order to dry the sample.</li>
		<li>Add 5 ml ultrapure water to the pellet and store in a vial wrapped well in Al foil (or other opaque covering). 
		Note: Once moved from toluene to water, the rods are not photostable, which is why they are covered. Even if kept in the dark the rods should be used as soon as possible, and it is not recommended to store rods in water for more than one month.</li>
	</ol>
	</li>
</ol>
4. Growth of Iridium Nanocrystalline Particles
<ol>
	<li>Sodium Hydroxide
	<ol>
		<li>In a plastic vial weigh out 1,450 mg NaOH. Dissolve NaOH in 20 ml ultrapure water. Solution should be clear with no solids.&#160;</li>
	</ol>
	</li>
	<li>Sodium Persulfate
	<ol>
		<li>In a plastic vial weigh out 950 mg NaS2O8. Dissolve NaS2O8 in 20 ml ultrapure water. Solution should be clear with no solids.</li>
	</ol>
	</li>
	<li>Sodium Nitrate
	<ol>
		<li>In a plastic vial weigh out 300 mg NaNO3. Dissolve NaNO3 in 18 ml ultrapure water. Solution should be clear with no solids.</li>
	</ol>
	</li>
	<li>Iridium Precursor Solution
	<ol>
		<li>In a plastic vial weigh out 50 mg Na3IrCl6. Dissolve Na3IrCl6 in 5.0 ml ultrapure water. Solution should be transparent brown (like scotch) with no solids.</li>
	</ol>
	</li>
	<li>Preparation of sample
	<ol>
		<li>Place a spectroscopic stirrer in a standard polystyrene cuvette. 
		Note: Because the solution is very basic, quartz and other glass cuvettes should not be used.</li>
		<li>Add 0.20 ml iridium precursor solution from step 4.4.1.</li>
		<li>Add 0.50 ml nitrate solution from step 4.3.1.</li>
		<li>Add 0.30 ml of seeded rods in water from section 3 (trace toluene from the ligand exchange may cause clouding of the cuvette wall).</li>
		<li>Add 0.50 ml of persulfate solution from step 4.2.1.</li>
		<li>Add 0.50 ml of sodium hydroxide solution from step 4.1.1.</li>
	</ol>
	</li>
	<li>Illumination of sample
	<ol>
		<li>Place the cuvette in a holder with stirring capabilities.</li>
		<li>Illuminate with 450 nm light at 100 mW for up to 4 hr. The solution should turn green and later blue.</li>
	</ol>
	</li>
	<li>Collecting sample
	<ol>
		<li>Pour solution (but not stir bar) into a centrifuge tube.</li>
		<li>Centrifuge at 7,700 x g for 10 min.</li>
		<li>Carefully decant the supernatant from the pellet, which should be green or blue depending on the reaction time selected. 
		Note: The pellet can now be collected or dispersed in a polar solvent through sonication for use in other experiments.</li>
	</ol>
	</li>
</ol>

<ol><li>Maeda, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photocatalyst+releasing+hydrogen+from+water%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Photocatalyst releasing hydrogen from water.</a> Nature. 440 (7082), 295-295 (2006).</li>
<li>Jacobson, M. Z., Colella, W. G., Golden, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cleaning+the+Air+and+Improving+Health+with+Hydrogen+Fuel-Cell+Vehicles%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Cleaning the Air and Improving Health with Hydrogen Fuel-Cell Vehicles.</a> Science. 308 (5730), 1901-1905 (2005).</li>
<li>Hoffmann, M. R., Martin, S. T., Choi, W., Bahnemann, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Environmental+Applications+of+Semiconductor+Photocatalysis%5BTitle%5D)+AND+%22+Chem.+Rev%22%5BJournal%5D)">Environmental Applications of Semiconductor Photocatalysis.</a> Chem. Rev. 95 (1), 69-96 (1995).</li>
<li>Dukovic, G., Merkle, M. G., Nelson, J. H., Hughes, S. M., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photodeposition+of+Pt+on+Colloidal+CdS+and+CdSe%2FCdS+Semiconductor+Nanostructures%5BTitle%5D)+AND+%22Adv.+Mater%22%5BJournal%5D)">Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures.</a> Adv. Mater. 20 (22), 4306-4311 (2008).</li>
<li>Menagen, G., Macdonald, J. E., Shemesh, Y., Popov, I., Banin, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Au+Growth+on+Semiconductor+Nanorods%3A+Photoinduced+versus+Thermal+Growth+Mechanisms%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Au Growth on Semiconductor Nanorods: Photoinduced versus Thermal Growth Mechanisms.</a> J. Am. Chem. Soc. 131 (47), 17406-17411 (2009).</li>
<li>Alemseghed, M. G., Ruberu, T. P. A., Vela, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Controlled+Fabrication+of+Colloidal+Semiconductor-Metal+Hybrid+Heterostructures%3A+Site+Selective+Metal+Photo+Deposition%5BTitle%5D)+AND+%22Chem.+Mater%22%5BJournal%5D)">Controlled Fabrication of Colloidal Semiconductor-Metal Hybrid Heterostructures: Site Selective Metal Photo Deposition.</a> Chem. Mater. 23 (15), 3571-3579 (2011).</li>
<li>Frame, F. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photocatalytic+Water+Oxidation+with+Nonsensitized+IrO2+Nanocrystals+under+Visible+and+UV+Light%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Photocatalytic Water Oxidation with Nonsensitized IrO2 Nanocrystals under Visible and UV Light.</a> J. Am. Chem. Soc. 133 (19), 7264-7267 (2011).</li>
<li>Iwase, A., Kato, H., Kudo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+Novel+Photodeposition+Method+in+the+Presence+of+Nitrate+Ions+for+Loading+of+an+Iridium+Oxide+Cocatalyst+for+Water+Splitting%5BTitle%5D)+AND+%22Chemistry+Letters%22%5BJournal%5D)">A Novel Photodeposition Method in the Presence of Nitrate Ions for Loading of an Iridium Oxide Cocatalyst for Water Splitting.</a> Chemistry Letters. 34 (7), 946-947 (2005).</li>
<li>Kalisman, P., Kauffmann, Y., Amirav, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photochemical+oxidation+on+nanorod+photocatalysts%5BTitle%5D)+AND+%22J.+Mater.+Chem%22%5BJournal%5D)">Photochemical oxidation on nanorod photocatalysts.</a> J. Mater. Chem. 3 (7), 3261-3265 (2015).</li>
<li>Ryu, W. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Crystalline+IrO2-decorated+TiO2+nanofiber+scaffolds+for+robust+and+sustainable+solar+water+oxidation%5BTitle%5D)+AND+%22J.+Mater.+Chem.+A%22%5BJournal%5D)">Crystalline IrO2-decorated TiO2 nanofiber scaffolds for robust and sustainable solar water oxidation.</a> J. Mater. Chem. A. 2 (16), 5610-5615 (2014).</li>
<li>Nakagawa, T., Bjorge, N. S., Murray, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Electrogenerated+IrOx+Nanoparticles+as+Dissolved+Redox+Catalysts+for+Water+Oxidation%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Electrogenerated IrOx Nanoparticles as Dissolved Redox Catalysts for Water Oxidation.</a> J. Am. Chem. Soc. 131 (43), 15578-15579 (2009).</li>
<li>Talapin, D. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Seeded+Growth+of+Highly+Luminescent+CdSe%2FCdS+Nanoheterostructures+with+Rod+and+Tetrapod+Morphologies%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Seeded Growth of Highly Luminescent CdSe/CdS Nanoheterostructures with Rod and Tetrapod Morphologies.</a> Nano Lett. 7 (10), 2951-2959 (2007).</li>
<li>Carbone, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Synthesis+and+Micrometer-Scale+Assembly+of+Colloidal+CdSe%2FCdS+Nanorods+Prepared+by+a+Seeded+Growth+Approach%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Synthesis and Micrometer-Scale Assembly of Colloidal CdSe/CdS Nanorods Prepared by a Seeded Growth Approach.</a> Nano Lett. 7 (10), 2942-2950 (2007).</li>
<li>Amirav, L., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photocatalytic+Hydrogen+Production+with+Tunable+Nanorod+Heterostructures%5BTitle%5D)+AND+%22J.+Phys.+Chem.+Lett%22%5BJournal%5D)">Photocatalytic Hydrogen Production with Tunable Nanorod Heterostructures.</a> J. Phys. Chem. Lett. 1 (7), 1051-1054 (2010).</li>
<li>Nakibli, Y., Kalisman, P., Amirav, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Less+Is+More%3A+The+Case+of+Metal+Cocatalysts%5BTitle%5D)+AND+%22J.+Phys.+Chem.+Lett%22%5BJournal%5D)">Less Is More: The Case of Metal Cocatalysts.</a> J. Phys. Chem. Lett. 6, 2265-2268 (2015).</li>
<li>Lupo, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ultrafast+Electron-Hole+Dynamics+in+Core%2FShell+CdSe%2FCdS+Dot%2FRod+Nanocrystals%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Ultrafast Electron-Hole Dynamics in Core/Shell CdSe/CdS Dot/Rod Nanocrystals.</a> Nano Lett. 8 (12), 4582-4587 (2008).</li>
<li>Raino, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Probing+the+Wave+Function+Delocalization+in+CdSe%2FCdS+Dot-in-Rod+Nanocrystals+by+Time-+and+Temperature-Resolved+Spectroscopy%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Probing the Wave Function Delocalization in CdSe/CdS Dot-in-Rod Nanocrystals by Time- and Temperature-Resolved Spectroscopy.</a> ACS Nano. 5 (5), 4031-4036 (2011).</li>
<li>Talapin, D. V., Lee, J. S., Kovalenko, M. V., Shevchenko, E. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prospects+of+Colloidal+Nanocrystals+for+Electronic+and+Optoelectronic+Applications%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications.</a> Chem. Rev. 110 (1), 389-458 (2010).</li>
<li>Kraus, R. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Room-Temperature+Exciton+Storage+in+Elongated+Semiconductor+Nanocrystals%5BTitle%5D)+AND+%22Phys.+Rev.+Lett%22%5BJournal%5D)">Room-Temperature Exciton Storage in Elongated Semiconductor Nanocrystals.</a> Phys. Rev. Lett. 98 (1), 017401(2007).</li>
<li>She, C., Demortière, A., Shevchenko, E. V., Pelton, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Using+Shape+to+Control+Photoluminescence+from+CdSe%2FCdS+Core%2FShell+Nanorods%5BTitle%5D)+AND+%22J.+Phys.+Chem.+Lett%22%5BJournal%5D)">Using Shape to Control Photoluminescence from CdSe/CdS Core/Shell Nanorods.</a> J. Phys. Chem. Lett. 2 (12), 1469-1475 (2011).</li>
<li>Manthiram, K., Beberwyck, B. J., Talapin, D. V., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Seeded+Synthesis+of+CdSe%2FCdS+Rod+and+Tetrapod+Nanocrystals%5BTitle%5D)+AND+%22J.+Vis.+Exp%22%5BJournal%5D)">Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals.</a> J. Vis. Exp. (82), (2013).</li>
<li>Yu, W. W., Qu, L., Guo, W., Peng, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Experimental+Determination+of+the+Extinction+Coefficient+of+CdTe%2C+CdSe%2C+and+CdS+Nanocrystals%5BTitle%5D)+AND+%22Chem.+Mater%22%5BJournal%5D)">Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals.</a> Chem. Mater. 15 (14), 2854-2860 (2003).</li>
<li>Miao, M. S., Seshadri, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rh2O3+versus+IrO2%3A+relativistic+effects+and+the+stability+of+Ir4%5BTitle%5D)+AND+%22J.+Phys.+Condens.+Matter%22%5BJournal%5D)">Rh2O3 versus IrO2: relativistic effects and the stability of Ir4.</a> J. Phys. Condens. Matter. 24 (21), 215503(2012).</li>
<li>Amirav, L., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Luminescence+Studies+of+Individual+Quantum+Dot+Photocatalysts%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Luminescence Studies of Individual Quantum Dot Photocatalysts.</a> J. Am. Chem. Soc. 135 (35), 13049-13053 (2013).</li>
<li>Vaneski, A., Schneider, J., Susha, A. S., Rogach, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aqueous+synthesis+of+CdS+and+CdSe%2FCdS+tetrapods+for+photocatalytic+hydrogen+generation%5BTitle%5D)+AND+%22APL+Materials%22%5BJournal%5D)">Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation.</a> APL Materials. 2 (1), 012104(2014).</li>
</ol>

The authors have nothing to disclose.

The synthesis of CdSe seeds and CdSe@CdS seeded rods has been well studied21,24,25. Slight modifications to the amounts, temperatures, and times for steps of the synthesis of these substrate particles can be used to tune their length, diameter, and/or morphology. The synthetic protocol described herein yields highly photoluminescent seeded-rods of uniform dimensions.
The ligand exchange procedure allows for the use of seeded rods in polar environments, in this case water. At the fin...

Photocatalysis presents an attractive and promising solution for renewable energy generation and other environmental applications such as water treatment and air purification1-3. Overall water splitting, driven by solar energy, could be a source of clean and renewable hydrogen fuel; however, despite decades of research, systems that are sufficiently stable and efficient for practical use have not yet been realized.
Both photodeposition and semiconductor-mediated photocatalysis rely on the same mechanism of separating photo-generated electron-hole pairs and driving them to the surface where they can initiate redox reactions. The similarities between these two processes make photodeposition an attractive synthetic tool for the field of photocatalysis4-6. This method is expected to take photocatalyst production to new and unexplored frontiers. It might potentially offer pristine control over the spatial arrangement of the different components in a heterostructures, and advance the ability to construct sophisticated nanoparticle systems. Ultimately the method will bring us one step closer to realizing an efficient photocatalyst for direct solar-to-fuel energy conversion.
We investigated the growth of IrO2 as a co-catalyst, as it is known to be an efficient catalyst for water oxidation7-11. A tunable structure of quantum dot (CdSe) embedded in a rod (cadmium sulfide)12,13 was used as our photocatalyst substrate14,15. It is currently undetermined whether the oxidative pathway occurs via a mediated pathway, or by a direct hole attack. Here, our knowledge and control over the photogenerated holes in the semiconductor heterostructure can be harnessed for a mechanistic study of oxidation reactions. This is made possible by the substrate architecture, which facilitates localization of confined holes16,17 and formation of a distinct oxidation reaction site on the rod. The use of nanoscale materials with localized charge carrier can be exploited for mechanistic studies of redox reactions by simple examination of the products. In this way photodeposition can be used as a unique probe of both reduction and oxidation reaction pathways. This is one example of the new and exciting possibilities afforded by the combination of photodeposition and cutting edge colloidal synthesis18-20.
The quest to develop an efficient photocatalyst for water splitting and renewable energy conversion has become an important thrust within the materials community. This has spurred worldwide interest in CdS, which is known to be highly active for hydrogen production, though it is hampered by photochemical instability. Our work here treats the Achilles heel of the material. IrO2 decorated CdSe@CdS rods demonstrate remarkable photochemical stability under prolonged illumination in pure water.

<table><tbody><tr><td>Sulfur (S)</td><td>Sigma</td><td>84683</td><td></td></tr><tr><td>Selenium (Se)</td><td>Sigma</td><td>229865</td><td></td></tr><tr><td>Cadmium Oxide (CdO)</td><td>Sigma</td><td>202894</td><td>Highly Toxic</td></tr><tr><td>n-Octadecylphosphonic acid (ODPA)</td><td>Sigma</td><td>715166</td><td></td></tr><tr><td>Propylphosphonic acid (PPA)</td><td>Sigma</td><td>305685</td><td>Highly regulated in some countries and regions</td></tr><tr><td>Butylphosphonic acid (BPA)</td><td>Sigma</td><td>737933</td><td>Alternative to PPA</td></tr><tr><td>Hexylphosphonic acid (HPA)</td><td>Sigma</td><td>750034</td><td>Alternative to PPA</td></tr><tr><td>Trioctylphosphonic oxide (TOPO)</td><td>Sigma</td><td>346187</td><td></td></tr><tr><td>Tri-n-octylphosphine, 97% (TOP)</td><td>Sigma</td><td>718165</td><td>Air sensitive</td></tr><tr><td>Spectrochemical Stirbar</td><td>Sigma</td><td>Z363545</td><td></td></tr><tr><td>Sodium Hydroxide</td><td>Sigma</td><td>S5881</td><td></td></tr><tr><td>Methanol</td><td>Sigma</td><td>322415</td><td></td></tr><tr><td>Toluene</td><td>Sigma</td><td>244511</td><td></td></tr><tr><td>Hexane</td><td>Sigma</td><td>296090</td><td></td></tr><tr><td>Octylamine</td><td>Sigma</td><td>74988</td><td></td></tr><tr><td>Nonanoic Acid</td><td>Sigma</td><td>N5502</td><td></td></tr><tr><td>Isopropanol</td><td>Sigma</td><td>278475</td><td></td></tr><tr><td>Mercaptoundecanoic Acid (MUA)</td><td>Sigma</td><td>674427</td><td></td></tr><tr><td>Tetramethylammonium Hydroxide (TMAH)</td><td>Sigma</td><td>T7505</td><td></td></tr><tr><td>Apiezon H Grease (high temperature grease)</td><td>Sigma</td><td>Z273562</td><td></td></tr><tr><td>Sodium Persulfate</td><td>Sigma</td><td>216232</td><td></td></tr><tr><td>Sodium Nitrate</td><td>Sigma</td><td>229938</td><td></td></tr><tr><td>Sodium Hexachloroiridate(III) hydrate</td><td>Sigma</td><td>288160</td><td></td></tr><tr><td>Mounted 455 nm LED</td><td>Thorlabs</td><td>M455L3</td><td></td></tr><tr><td>Cuvette Holder</td><td>Thorlabs</td><td>CVH100</td><td></td></tr><tr><td>25 ml 3-neck Round Bottom Flask</td><td>Chemglass</td><td>CG-1524-A-02</td><td></td></tr><tr><td>Liebig Condensor</td><td>Chemglass</td><td>CG-1218-A-20</td><td></td></tr><tr><td>T-Joint Adapter</td><td>Chemglass</td><td>AF-0509-10</td><td></td></tr></tbody></table>

photochemical oxidative growth of iridium oxide nanoparticles on cdse@cds nanorods

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).

Transmission electron micrographs (TEM) were collected in order to see the distribution of iridium oxide on the seeded rods (Figure 1). TEM samples were prepared by pipetting a drop of dissolved particles onto a TEM grid. X-ray diffraction (XRD, Figure 2) and X-ray photoelectron spectra (XPS, Figure 3) were used to characterize the observed growth as a mix of crystalline IrO2 and Ir2O3. Preparation of XRD ...

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 ...

The overall goal of this procedure is to grow iridium oxide nanocrystals on a semiconductor substrate by photochemical oxidation. Photochemical oxidation as a synthetic tool expands the methods by which chemists can create new hybrid materials. They can photocatalyze production to unexplored frontiers.Our work treats the Achilles heel of cadmium sulfide, which is known to be highly active for hydrogen production, but is hampered by photochemical instability. Photochemical oxidation, when applied on nanoscale materials with localized charge carriers can also be exploited from a kinistic styleze of redox reactions by simple examination of the products. To start, first synthesize cadmium sulfide-cadmium selenide seeded rods, and then suspend them in toluene solution indicated in the text protocol.Transfer about half of the solution to a centrifuge tube, and add up to a one-half volume of methanol to precipitate the rods. Centrifuge the tube at 3, 400 Gs for five minutes, and decant the supernatant. Retain the pellet for later use.Next, add 250 milligrams of mercaptoundecanoic acid and 400 milligrams of tetramethylammonium hydroxide to 10 milliliters of methanol in a centrifuge tube. Vortex until all the solids are dissolved. Add the methanol mixture to the cadmium sulfide-cadmium selenide seeded rod pellet, and shake the tube by hand to fully dissolve it.Allow the solution to sit for at least one hour. After one hour, split the solution into two centrifuge tubes, and add 20 milliliters of toluene to each tube. Centrifuge the tubes at 7, 700 Gs for 15 minutes.Carefully decant the clear supernatant, and invert the centrifuge tubes to dry the samples. Add five milliliters of ultrapure water to the pellets, and then store the rods in foil-wrapped vials. To begin, make solutions of iridium precursor, sodium nitrate, sodium persulfate, and sodium hydroxide as indicated in the text protocol.Add 0.50 milliliters of the nitrate solution to 0.20 milliliters of the iridium precursor in a standard polystyrene cuvette equipped with a spectroscopic stir bar. Next, add 0.30 milliliters of the seeded rods in water, followed by 0.50 milliliters of the persulfate solution, and 0.50 milliliters of the sodium hydroxide solution. Place the cuvette in a holder, and stir the solution.Then illuminate the sample at 450 nanometers and 100 milliwatts for up to four hours. The solution should turn green, and then blue. After the desired incubation time, transfer the solution to a tube, and centrifuge for 10 minutes at 7, 700 Gs.Carefully decant the supernatant and retain the pellet.Disperse by sonicating in polar methanol solvent for further use. The visual appearance of the cadmium sulfide-cadmium selenide rods changes when coated with iridium oxide using irradiation. The uncoated rods begin orange-red in color, which after two hours of illumination turns green, and then blue after four hours of illumination.Transmission electron micrographs were used to analyze the growth of the iridium oxide particles on the cadmium sulfide-cadmium selenide seeded rods over time. Control samples with no iridium oxide have rods of four to five nanometers in diameter. Samples illuminated for 10 minutes to four hours show the progression from small to larger particles with a full coating of iridium oxide.Rods that were illuminated for four hours have a total diameter of nine to ten nanometers, with a two to three nanometer thick outer coating of iridium oxide evident after two hours of illumination. Once mastered, this technique can be done in a few hours if it is properly performed. After watching this video, you should have a good understanding of how to photochemically grow iridium oxide on seeded rods.The methods used in this procedure can be extended towards the photochemical growth of other metal oxides as well. Don't forget that working with cadmium oxide and highly caustic solutions can be extremely hazardous, and precautions such as working in a glove box and wearing protective clothing should always be taken while performing this procedure.

photochemical-oxidative-growth-iridium-oxide-nanoparticles-on-cdsecds

Research

JoVE Journal

Chemistry

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging.  Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

Compact Quantum Dots for Single-molecule Imaging

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

Hydroquinone Based Synthesis of Gold Nanorods

Here, we prepare and characterize novel tree-like hierarchical ZnO/CdSSe nanostructures, where CdSSe branches are grown on vertically aligned ZnO nanowires. The resulting nanotrees are a potential material for solar energy conversion and other opto-electronic devices.

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we present a protocol for the synthesis and characterization of cerium oxide nanoparticles (nanoceria) for ROS (reactive oxygen species) scavenging in vivo, nanoceria imaging in plant tissues by confocal microscopy, and in vivo monitoring of nanoceria ROS scavenging by confocal microscopy.

Catalytic Scavenging of Plant Reactive Oxygen Species In Vivo by Anionic Cerium Oxide Nanoparticles

A protocol for anisotropic photodeposition of Pd onto aqueously-suspended Au nanorods via localized surface plasmon excitation is presented.

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation

A synthesis technique to prepare the visible-light-responsive ZnCoS/ZnCdS with twin crystal structure photocatalyst and the photoredox reaction testing technique of its photocatalytic activity and selectivity in H2 evolution and benzaldehyde production is presented.

Synthesis and Performance Evaluations of ZnCoS/ZnCdS with Twin Crystal Structure for Multifunctional Redox Photocatalysis in Energy Applications

Learn photochemical oxidative growth of iridium oxide nanoparticles on CdSe@CdS nanorods for enhanced hydrogen production. This method improves cadmium sulfide stability using photochemical oxidation techniques.

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

Explore More Videos