The authors acknowledge financial support from the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy.

1. Stripping Copper/Tin Wires
<ol>
	<li>Heat commercially obtained stripping solution.
	<ol>
		<li>Pour commercial industrial grade stripping solution into a stainless steel beaker (7.6 cm in diameter and 8.5 cm in height) to a depth of about 5 mm from the bottom. Place the beaker on to a hot plate. Begin heating a slow rate of about 5 &#176;C/min.</li>
		<li>Immerse a portable thermocouple into the solution to closely monitor the temperature ramp of the solution and adjust the heating rate of the hot plate to maintain at the required heating rate.</li>
	</ol>
	</li>
	<li>Setting up of the Cu/Sn wire on the jig for preparing reference wires.
	<ol>
		<li>Wind a thick copper wire in the form of a jig (4 cm wide and 7 cm long). Mount the commercial Cu/Sn (or pure Cu) wire (25.4 &#181;m in diameter), plated with a thin layer of Sn and electronically insulated with a polyurethane coating) onto the jig as shown in Figure 1a. 
		NOTE: These wires are extremely delicate and may break if handled rough.</li>
	</ol>
	</li>
	<li>Stripping the polymer
	<ol>
		<li>Once the temperature of the stripping solution reads about 85 &#176;C on the thermocouple, stop heating the solution and immerse the wire mounted jig into the solution.</li>
		<li>Leave the jig inside the solution for 15 s and then rinse the jig in DI water for another 15 s to wash excess stripping solution adsorbed onto the wire.</li>
		<li>Check the wire for exposed Sn (appears as silvery white color) and repeat step 1.3.2 until the polymer is completely stripped. 
		CAUTION: Long term exposure of the wire to the stripping solution can etch away Sn coating and expose a reddish-brown Cu wire underneath. If the wires are being prepared for impedance spectroscopy analysis, the presence of Sn plating is essential.</li>
		<li>Rinse the jig in DI water and dry in air at room temperature (25 &#176;C).</li>
		<li>Cut the wires in the middle of the stripped regions to obtain wires with both ends with exposed Sn (or Cu over excess stripped wires). The size of each wire is approximately 10 cm.</li>
	</ol>
	</li>
</ol>
2. Reference Wire Preparation
<ol>
	<li>To make the reference wire contacts, connect the wires to an electrical wire and solder the junction.
	<ol>
		<li>From a roll of electrical circuit wires, cut pieces of 10 cm and strip the insulation cover from both the ends to expose about 2 cm of metal.</li>
		<li>Mount one end of the polymer stripped wire on to the end of the exposed electrical wire and solder the junction to form an electrical contact between the wires.</li>
		<li>Measure the resistance between the exposed Sn (or Cu) wire and the exposed electrical wire. 
		NOTE: The typical resistance values are between 6-8 &#8486;.</li>
		<li>Transfer one wire each with Sn exposed and with Cu exposed into an Argon filled glovebox for assembly into a cell.</li>
	</ol>
	</li>
	<li>Mount a pressed and flattened Li metal foil to the Cu exposed reference wire
	<ol>
		<li>Cut a small piece of Li metal (not more than 5 mm x 5 mm) from a large Li foil inside the glovebox. 
		NOTE: Use dedicated equipment for contact with Li metal and store inside the glovebox to prevent cross contamination and subsequent electrical micro-short.</li>
		<li>Using a roller covered with a polymer tape (to prevent sticking of the Li metal onto the metallic roller surface), roll the Li metal piece on a Teflon platform under Ar.</li>
		<li>Continue rolling to achieve a foil thickness of approximately 25 &#181;m. Check the thickness using a screw gauge.</li>
		<li>Upon obtaining the desired thickness of the Li metal foil, bend the foil at the center to form a U- shape. Place the Cu exposed wire in between the bend such that Cu is in contact with the Li metal and press the fold to encapsulate Cu wire between the two Li layers. 
		NOTE: Maintain extreme caution while encapsulating Cu wire so as to ensure covering all of the exposed tip. Cu is for electronic conductance only and contact of Cu to the electrolyte will result in reading a mixed surface potential generating erroneous voltage values in the data.</li>
	</ol>
	</li>
</ol>
3. Cell Assembly and Data Acquisition
<ol>
	<li>Place both the Li metal reference and the Sn reference wires in between the Li-ion cell assembly.
	<ol>
		<li>Place the negative electrode in the fixture such that the center of the electrode is slightly shifted from the center of the fixture. Add 400 &#181;L of the electrolyte (1.2M LiPF6 in Fluoroethylene Carbonate (FEC):Ethyl Methyl Carbonate EMC (5:95 w/w)) to wet the entire electrode.</li>
		<li>Place one separator on top of the electrode and using a organophobic sweep, gently eliminate trapped air bubbles between the separator and the electrode. Adjust the placement of the separator to ensure concentricity with the fixture to completely insulate the base of the fixture from the positive electrode and avoid electric short inside the cell. 
		NOTE: Large electrodes tend to trap air pockets between the separator and the electrodes as they curl upon addition of the electrolyte. These air pockets need to be removed to ensure proper contact of the separator with the electrodes. The air bubbles increase the impedance of the cell and inhibit ion transfer.</li>
		<li>Add two drops (about 10 &#181;L) of electrolyte, one at 2 mm away from the cell sandwich and another one at the center of the electrode. Position the Sn exposed tip of the reference wire at the center of the electrode and the Li metal foil (encapsulated onto Cu wire) on the drop away from the electrode. The surface tension between the metals and the electrolyte drops hold the wires in position.</li>
		<li>Add one more drop (about 10 &#181;L) of electrolyte onto the Li metal after placing the wire in position.</li>
		<li>Remove additional air bubbles between the Li foil and the separator with the Teflon sweep. Add another 400 &#181;L of the electrolyte.</li>
		<li>Place a second separator aligned to the first separator such that both the reference wires are sandwiched between the two separators. Remove any additional air bubbles. 
		CAUTION: While placing the second separator, excessive tension can break the reference wires. Leave extra wire inside the cell to reduce tension in the wire.</li>
		<li>Wet the positive electrode with 400 &#181;L of the electrolyte. Place the electrode aligned with the negative electrode on top of the second separator.</li>
		<li>Place the stainless steel spacer onto the positive electrode carefully to not disturb the cell stack alignment. 
		NOTE: Misaligned electrodes result in inhomogeneous current distributions and reduced cell capacity due to reduced access of active cell area.</li>
		<li>Place two stainless steel wave springs on the puck to accommodate for cell volume changes and pressure build up which ensure proper electric contact between the electrodes and the fixture terminals. Close the fixture. Since the setup is not hermetically sealed, the tests are conducted inside the glove box in an inert atmosphere.</li>
	</ol>
	</li>
	<li>Record the data from the Li metal reference wire for individual electrode voltage profiles
	<ol>
		<li>Connect the auxiliary reference terminal of the cycler to the Li metal while the positive and negative electrode terminals of the cycler are connected to the respective electrodes. 
		NOTE: During the cycling of the cell, the cycler reads the potential difference between the positive terminal and the RE as Aux1 output and the negative electrode and the reference as Aux2. While the Li metal wire is connected, Aux1 and Aux2 are the potentials of individual electrodes with respect to Li metal.</li>
	</ol>
	</li>
	<li>Lithiate the Sn wire in situ to record electrochemical impedance spectroscopy (EIS).
	<ol>
		<li>Apply a constant current of 5 &#181;A for 6 h between the positive electrode and the Sn wire with an upper voltage cutoff of 4 V to electrochemically lithiate the Sn. The potential of Li/Sn alloy thus formed is close to that of the Li metal. Disconnect the terminals and allow the wire to equilibrate for 2 h. 
		NOTE: Ensure extremely low current (close to 0 A) in the circuit to confirm complete lithiation of the Sn wire.</li>
		<li>Alter cycler connections to Li metal to the auxiliary terminal of the cycler and Sn wire to the negative terminal of the cycler and ensure the reading of Aux2 close to 0 V. A lithiated phase of Sn is obtained, denoted as LixSn.</li>
		<li>Re-connect the positive and negative terminals of the cycler to the respective electrodes of the cell and the auxiliary terminal to LixSn wire.</li>
	</ol>
	</li>
	<li>Record EIS for (i) cathode vs.anode, (ii) cathode vs. lithiated Sn wire and (iii) anode vs. lithiated Sn wire. The impedance of (i) is the sum of the impedances obtained in (ii) and (iii). The potentiostat consists of two terminals to record the voltages and two for current outputs for each electrode.
	<ol>
		<li>To obtain the full cell spectra, connect voltage and current terminals to the respective positive and negative electrodes of the cell.</li>
		<li>For the positive electrode impedance, connect the voltage and current positive terminals (also known as working electrode, WE) to the positive electrode, and connect the negative terminals (also known as the counter electrode, CE) to the LixSn reference electrode.</li>
		<li>For the negative electrode impedance, connect the WE terminals to the negative electrode and connect the CE terminals to the LixSn reference electrode.</li>
		<li>To record the EIS, supply AC currents or varying frequencies to cycle the electrochemical couple between a small voltage amplitude (5 mV) and plot the impedance response as imaginary component vs. the real component.</li>
	</ol>
	</li>
</ol>

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I. Experimental investigation.</a> Journal of Power Sources. 196 (12), 5334-5341 (2011).</li><li>Li, S. E., Wang, B., Peng, H., Hu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+electrochemistry-based+impedance+model+for+lithium-ion+batteries.">An electrochemistry-based impedance model for lithium-ion batteries.</a> Journal of Power Sources. 258, 9-18 (2014).</li></ol>

The authors have nothing to disclose.

Figure 2a is the voltage profile of the full cell while Figure 2b and 2c show voltage profiles corresponding to the positive and the negative electrode vs Li/Li+ couple while the full cell is cycled between 3 and 4.4 V. It can be seen that as the full cell scans between 3 and 4.4 V, the positive electrode experiences voltages between 3.65 V and 4.45 V and the negative electrode between 0.65 V and 0.05 V vs. Li/Li+ ...

The demand for high energy densities from Li-ion batteries (LIBs) is driving research towards understanding fundamental factors that limit Li- ion cell performance1. High voltage operation of cells containing a new generation of layered transition metal oxide cathodes, graphite anodes and organic carbonate electrolytes is associated with several parasitic reactions2,3. Some of these reactions consume Li - ion inventory and often result in significant impedance rise of the cell4,5,6,7. Loss of Li- ion also results in a net shift of the surface potentials of electrodes. Monitoring of voltage changes on an individual electrode in a full cell versus a reference electrode (RE) can be performed in commercial 3-electrode cell designs8,9,10,11,12,13,14. Information pertaining to voltage profiles and the impedance changes on individual electrodes promotes a deeper understanding of the fundamental degradation mechanisms of a LIB. Conventional 3-electrode cells contain Li metal as a reference electrode, which facilitates a distinct understanding of the electrochemical processes at each electrode. Li-metal in contact with the organic electrolyte undergoes spontaneous surface modification and the contribution of this surface layer on Li cannot be quantified15. Several 3-electrode configurations such as (a) T-model, (b) a micro-RE positioned coaxial to both the working and the counter electrode, (c) a coin cell with an RE at the back of the counter electrode, etc. have been proposed earlier. Most of these cell configurations have the RE positioned away from the cell sandwich, generating significant drift in the impedance data due to low conductivity of the electrolyte. It has been proven that a RE with a stable potential throughout the measurement must be stationed in the center of the sandwich to ensure reliable impedance data.
In order to address these discrepancies, we have designed a cell setup involving a fourth RE16. An ultra-thin Sn plated Cu wire is sandwiched in between the electrodes of a battery that can be electrochemically lithiated in situ to form a LixSn alloy. As Sn undergoes lithiation, the voltage of the reference wire drops and a completely lithiated wire has a potential close to 0 V vs. Li+/Li17. The lithiated composition has a potential comparable to Li metal and the metastable alloys facilitate a stable potential during the time period of the measurement. A Li metal exposed to the electrolyte is prone to electrolyte decomposition products forming surface layers. An EIS measurement to probe the impedance of individual electrodes by collecting spectra between one of the electrodes and the Li metal reference as coupled have not been reliable due to the contribution of these layers on the impedance. Although electrolyte reduction is inevitable also on the Li-Sn surface, an in situ lithiated reference wire has the following advantages: (a) no constant electrolyte decomposition products as the voltage is always above the decomposition potential of the electrolyte unless lithiated ,implying no loss of Li inventory in the system to interfacial layers; (b) layers formed during lithiation of the Sn wire are over a very small area, providing negligible contribution to the EIS data; and (c) the formed products degrade as the Sn wire loses Li and the potential of the wire increases, resulting in lithiation of fresh Sn wire during every lithiation and thus formation of very thin interfacial layers every time instead of increased thickness of these layers. Spectra recorded with these alloys as reference provide more accurate and reliable data of the electrode impedance. We conducted tests with standard 2032-type coin cells and 4-electrode RE cells to validate our design. Results from these tests and our interpretation of the data will be used as a representative result to explain the efficacy of our protocol. The 3-4.4 V cycling followed a standard protocol, which included formation cycles, aging cycles, and periodic AC impedance measurements during the cycling. The coin cell measurements provide valuable information on the parameters such as cycle life, capacity retention, AC impedance changes, etc. RE cells enable monitoring voltage changes and impedance rise on individual electrodes. Our mechanistic understanding into the capacity fade and impedance rise can provide guidelines for the development of electrolyte systems and understand contributions for capacity loss from each electrode during high-voltage cell operation.
Our cells contained Li1.03 (Ni0.5Co0.2Mn0.3)0.97O2 (denoted here as NMC532)-based positive electrodes, graphite-based negative electrodes (denoted here as Gr) and a 1.2 M solution of LiPF6 in Fluoroethylene Carbonate (FEC):Ethyl Methyl Carbonate (EMC) (5:95 w/w) as the electrolyte. The electrodes used in this study are standard electrodes fabricated at the Cell Analysis, Modeling and Prototyping (CAMP) Facility at Argonne National Laboratory. The positive electrode consists of NMC532, conductive carbon additive (C-45) and polyvinylidene fluoride (PVdF) binder in a weight ratio of 90:5:5 on a 20 &#181;m thick Al current collector. The negative electrode consists of graphite, mixed with C-45, and PVdF binder in a weight ratio of 92:2:6 on a 10 &#181;m thick Cu current collector. Circular discs of 5.08 cm diameter were punched from the electrode laminates and the separators were punched with a 7.62 cm die for use in fixtures with 7.62 cm inner diameter. These electrodes were dried at 120 &#176;C and the separators at 75 &#176;C in a vacuum oven for at least 12 h prior to the cell assembly. A schematic representation of the fixture design is represented in Figure 1. Large fixtures and electrodes ensure minimum inhomogeneities in current distributions per unit area, thus, providing the least distortions in the impedance spectra. The 3-4.4 V cycling followed a standard protocol, which included two formation cycles at a C/20 rate, 100 ageing cycles at a C/3 rate and two diagnostic cycles at C/20. All battery tests were conducted at 30 &#176;C. Electrochemical cycling data was measured using a battery cycler and the electrochemical impedance spectroscopy (EIS) is performed using a potentiostat system.

<table border="0" cellpadding="0" cellspacing="0" width="645">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Insulstrip 220</td>
			<td style="width:143px;">Ambion Corporation</td>
			<td style="width:119px;">081607-1</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium Hydroxide (23 wt%)</td>
			<td style="width:143px;">Ambion Corporation</td>
			<td>1310-73-2</td>
			<td>Contents of Insulstrip 220</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Furfuryl Alcohol (10 wt%)</td>
			<td style="width:143px;">Ambion Corporation</td>
			<td style="width:119px;">98-00-0</td>
			<td>Contents of Insulstrip 220</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NCM523</td>
			<td>TODA America</td>
			<td style="width:119px;">NM4100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C-45&#160;</td>
			<td>Timcal Inc.</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">polyvinylidene fluoride (PVdF)</td>
			<td>Sigma Aldrich</td>
			<td style="width:119px;">427152</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sn over Cu wire</td>
			<td style="width:143px;">Kanthal</td>
			<td style="width:119px;">MELT # 24633</td>
			<td>Custom ordered</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Battery cycler</td>
			<td style="width:143px;">Maccor USA</td>
			<td style="width:119px;">Series 2300&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Potentiostat</td>
			<td style="width:143px;">Solartron Analytical</td>
			<td style="width:119px;">1470 E</td>
			<td></td>
		</tr>
	</tbody>
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in situ lithiated reference electrode: four electrode design for in-operando impedance spectroscopy

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

Figure 2 is a representative profile of the voltages of individual electrodes with 1.2M LiPF6 in (FEC):EMC (5:95 w/w) as the electrolyte during the first and second cycles of formation. Figure 3 shows the EIS spectra of the cell after three formation cycles and at the end of the cycle life ageing protocol. The ability to re-lithiate the RE to obtain EIS data aids in precise tracking of the impedance changes in individu...

Watch this Scientific Journal Video about In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy at JoVE.com

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate ...

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Chemistry

8.7K Views.  Argonne National Laboratory. The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

Video: In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended solvent window, low background currents, corrosion resistance, etc., arise from the catalytically inert nature of the surface. However, if during the growth process, non-diamond-carbon (NDC) becomes incorporated into the electrode matrix, the electrochemical properties will change as the surface becomes more catalytically active. As such it is important that the electrochemist is aware of the quality and resulting key electrochemical properties of the BDD electrode prior to use. This paper describes a series of characterization steps, including Raman microscopy, capacitance, solvent window and redox electrochemistry, to ascertain whether the BDD electrode contains negligible NDC i.e. negligible sp2 carbon. One application is highlighted which takes advantage of the catalytically inert and corrosion resistant nature of an NDC-free surface i.e. stable and quantifiable local proton and hydroxide production due to water electrolysis at a BDD electrode. An approach to measuring the local pH change induced by water electrolysis using iridium oxide coated BDD electrodes is also described in detail.

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

A protocol is described for the characterization of the key electrochemical parameters of a boron doped diamond (BDD) electrode and subsequent application for in situ pH generation experiments.

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended ...

X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies.
The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2&#8729;4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as &#34;glass induced metal corrosion&#34;.
For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2&#8729;6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment.
The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures.

Modern high resolution X-ray powder diffraction (XRPD) in the laboratory is used as an efficient tool to determine crystal structures of long-known corrosion products on historic objects.

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 &#181;m grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes in detail how to fabricate and operate microfluidic devices for X-ray diffraction data collection at room temperature. Additionally, it describes how to monitor protein crystallization by dynamic light scattering and how to process and analyze obtained diffraction data.

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The ...

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 ...

A Closed-Type Wireless Nanopore Electrode for Analyzing Single Nanoparticles

Measuring the intrinsic features of single nanoparticles by nanoelectrochemistry holds deep fundamental importance and has potential impacts in nanoscience. However, electrochemically analyzing single nanoparticles is challenging, as the sensing nanointerface is uncontrollable. To address this challenge, we describe here the fabrication and characterization of a closed-type wireless nanopore electrode (WNE) that exhibits a highly controllable morphology and outstanding reproducibility. The facile fabrication of WNE enables the preparation of well-defined nanoelectrodes in a general chemistry laboratory without the use of a clean room and expensive equipment. One application of a 30 nm closed-type WNE in analysis of single gold nanoparticles in the mixture is also highlighted, which shows a high current resolution of 0.6 pA and high temporal resolution of 0.01 ms. Accompanied by their excellent morphology and small diameters, more potential applications of closed-type WNEs can be expanded from nanoparticle characterization to single molecule/ion detection and single-cell probing.

Here, we present a protocol for fabrication of a closed-type wireless nanopore electrode and subsequent electrochemical measurement of single nanoparticle collisions.

Measuring the intrinsic features of single nanoparticles by nanoelectrochemistry holds deep fundamental importance and has potential impacts in ...

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. The versatility of the GSMLCs is demonstrated in the context of a study about etching and growth dynamics of gold nanostructures from a HAuCl4 precursor solution. GSMLCs combine the advantages of conventional silicon- and graphene-based liquid cells by offering reproducible well depths together with facile cell manufacturing and handling of the specimen under investigation. The GSMLCs are fabricated on a single silicon substrate which drastically reduces the complexity of the manufacturing process compared to two-wafer-based liquid cell designs. Here, no bonding or alignment process steps are required. Furthermore, the enclosed liquid volume can be tailored to the respective experimental requirements by simply adjusting the thickness of a silicon nitride layer. This enables a significant reduction of window bulging in the electron microscope vacuum. Finally, a state-of-the-art quantitative evaluation of single particle tracking and dendrite formation in liquid cell experiments using only open source software is presented.

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

A protocol for preparation of graphene-supported microwell liquid cells for in situ electron microscopy of gold nanocrystals from HAuCl4 precursor solution is presented. Furthermore, an analysis routine is presented to quantify observed etching and growth dynamics.

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. ...

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is &#34;blind&#34; with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites.
The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

The use of FTIR spectroscopy for investigation of the surface properties of polycrystalline solids is described. Preparation of sample pellets, activation procedures, characterization with probe molecules and model studies of CO2 adsorption are discussed.

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids ...

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

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Chapters in this video

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

A Closed-Type Wireless Nanopore Electrode for Analyzing Single Nanoparticles

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO₂ Adsorption in UiO-66 Metal-Organic Framework