Gamry Instruments Cell for Ring-Disk Electrodes

Limited Warranty

Gamry Instruments, Inc. warrants to the original user of this product that it shall be free of defects resulting from faulty manufacture of the product or its components for a period of one year from the original shipment date of your purchase.

Gamry Instruments, Inc. makes no warranties regarding either the satisfactory performance of this Cell Kit or the fitness of the product for any particular purpose. The remedy for breach of this Limited Warranty shall be limited solely to repair or by replacement, as determined by Gamry Instruments, Inc., and shall not include other damages.

Gamry Instruments, Inc. reserves the right to make revisions to the product at any time without incurring any obligation to install same on systems previously purchased. All product specifications are subject to change without notice.

There are no warranties which extend beyond the description herein. This warranty is in lieu of, and excludes any and all other warranties or representations, expressed, implied or statutory, including merchantability and fitness, as well as any and all other obligations or liabilities of Gamry Instruments, Inc.; including but not limited to, special or consequential damages.

This Limited Warranty gives you specific legal rights and you may have others which vary from state to state. Some states do not allow for the exclusion of incidental or consequential damages.

No person, firm or corporation is authorized to assume for Gamry Instruments, Inc., any additional obligation or liability not expressly provided herein except in writing duly executed by an officer of Gamry Instruments, Inc.

Contact and Support

For assistance or replacement parts, please visit the Gamry Instruments service and support page at www.gamry.com/service-support/. This page provides information on installation, software updates, and training, along with links to the latest documentation.

Alternatively, you can contact Gamry Instruments via email or by telephone:

• Internet: www.gamry.com/service-support/
• Telephone: (215) 682-9330 (9:00 AM–5:00 PM US Eastern Standard Time)
• Toll-free (US & Canada): (877) 367-4267

Contact your local Gamry sales representative for special requirements or accessories.

Disclaimer

The information in this manual has been carefully checked and is believed to be accurate as of the time of printing. However, Gamry Instruments, Inc. assumes no responsibility for errors that might appear.

Copyrights and Trademarks

RDE Cell Manual copyright © 2009–2021 Gamry Instruments, Inc.

Viton® and Kalrez® are registered trademarks of DuPont Dow Elastomers, LLC. Pyrex® is a registered trademark of Corning Incorporated. ACE-Thred™ is a trademark of Ace Glass, Inc.

No part of this document may be copied or reproduced in any form without the prior written consent of Gamry Instruments, Inc.

Introduction

Gamry Instruments designed the Cell kit for use with the RDE710 Rotating Electrode and Disk and Cylinder electrodes.

A reference electrode is not included in the cell kit. Gamry Instruments sells three types of reference electrodes (SCE, Ag|AgCl, and Hg|Hg2SO4) suitable for use with the EuroCell kit. Users should order their reference electrode separately.

The Cell utilizes five standard ports for its functions, allowing customization with Gamry's standard fittings or additional components.

Temperature control is crucial for electrochemical experiments, influencing reaction rates. Gamry offers a special jacketed version of the Cell body for use with a circulating water bath to achieve accurate temperature control.

Chemical Compatibility of the Cell

The Cell components are selected for chemical inertness. Materials in contact with the test solution include:

• Borosilicate glass (Pyrex® or equivalent)
• Unfired glass frit
• PTFE
• Polyethylene
• ACE Glass's FETFE O-ring material

Chemical resistance tables are available online. FETFE offers good chemical resistance. ACE-Thred™ fittings are typically nylon.

Caution: Nylon bushings and FETFE O-rings may not be suitable for all electrolytes, especially non-aqueous media. For enhanced chemical resistance, consider PTFE and Kalrez® fittings from ACE Glass (www.aceglass.com).

The Gamry Cell for Ring Disk Electrodes is not designed for electrolytes that dissolve glass, such as extremely basic solutions or HF-containing solutions.

Caution: Glass components and frits are not suitable for extremely basic solutions or solutions containing hydrofluoric acid. For such applications, an all-plastic cell is recommended.

Polyethylene stoppers can be adapted for gas venting. For aggressive solvents, glass or PTFE stoppers may be preferred.

Unpacking and Checking a Cell Kit

This section guides users on checking a newly received Cell Kit for shipping damage. Inspect glass components carefully for chips or cracks.

Warning: Do not use chipped or cracked glass parts, as they pose a significant safety hazard due to sharp edges.

If parts are broken, contact Gamry Instruments or your local representative. Retain original packaging for shipping claims.

Parts List

Verify kit contents against the packing list. Components are labeled with Gamry Instruments, Inc. part numbers.

Assembly of and Use of Your Cell Kit

Standard Cell Configuration

The standard configuration includes:

• A standard cell body for room temperature use.
• A rotating electrode in the central 24/40 standard taper port (sold separately).
• A three-way gas purge/blanket/vent adapter in one 14/20 standard taper port.
• A graphite-rod counter electrode in one #7 ACE-Thred™ port.
• A reference electrode (sold separately) and bridge tube in one #7 ACE-Thred™ port.
• One unused 14/20 standard-taper port (can be closed with a stopper).

Users can customize the cell configuration based on their needs.

Cell Assembly: General Information

It is recommended to assemble the cell dry first. The cell body should be clamped to a ring stand, as it is unstable on a flat surface and can roll off.

Caution: Always assume the cell body will roll if laid down. Use a cell stand kit (part # 990-00202) to prevent accidents.

Standard-taper ground-glass joints should not be greased.

Caution: Do not grease ground-glass joints on this Cell, as it is unnecessary and can cause problems.

Diagram Description (Figure 1): A diagram illustrating the standard configuration of an RDE Cell, showing the cell body with various adapters and electrodes connected to its ports, including a gas bubbler assembly and a reference electrode bridge tube.

Maintain cell cleanliness to ensure reproducible results. Avoid touching wetted surfaces after cleaning.

ACE-Thred™ connectors are designed for cylindrical objects and should be tightened finger-tight only.

Warning: Never use tools to tighten ACE-Thred™ fittings, as over-tightening can break the cell and cause injury.

A #7 ACE-Thred™ is specified for objects with a diameter between 6.5 mm and 7.5 mm.

Gas-flow Overview and Terminology

The Gas Bubbler Assembly is used for removing atmospheric oxygen (de-oxygenation) via gas purging or sparging (e.g., with nitrogen). Blanketing involves flowing inert gas over the solution surface after purging.

Bubbling gas can cause noise; blanketing can be used during data acquisition. Some Gamry systems offer automatic gas flow control.

Pre-saturation of the Purge Gas: Dry purge gas can cause electrolyte evaporation. Pre-saturating the gas using a gas washing bottle can prevent this error.

Cell Gas Bubbler Assembly: Consists of a Gas Flow Adapter, Gas Bubbler Tube, #7 ACE-Thred™ nut, and an ACE-Thred™-To-Hose adapter.

Diagram Description (Figure 2): A diagram of the Gas Bubbler Assembly, showing a glass tube with a side barb fitting, connected via an adapter to a source of gas. This assembly is used for purging, blanketing, or venting the cell.

Warning: Always provide a vent for gas to escape the cell. Failure to vent can cause cell damage, electrolyte loss, and personal injury.

The Gas Flow Adapter typically fits into a 14/20 ground-glass port, and the Gas Bubbler Tube into a #7 ACE-Thred™ port.

Attaching Gas Tubing to the Cell

The Gas Bubbler Tube's orifice should be positioned in the cell's electrolyte. The hose barb can serve as a vent or blanket gas inlet.

Warning: Ensure gas flow is controlled with a needle valve, turned off during connections. Excessive gas flow can damage the cell and cause electrolyte loss.

Connect the gas-flow system and add electrolyte before turning on the needle valve. Open slowly.

A three-way valve is useful for switching between purge and blanket modes.

• Connect purge gas to the ACE-Thred™-To-Hose adapter.
• Connect blanket gas to the hose barb.
• Use a spare port for a vent.

Manual mode switching involves adjusting the Gas Bubbler Tube position.

Counter Electrode Assembly

The counter electrode (or auxiliary electrode) provides or accepts electrons. It is typically an inert metal or carbon electrode.

A glass frit can be used as a diffusion barrier to isolate the counter electrode compartment.

High-Density Graphite Counter Electrodes

The kit includes a high-density graphite rod counter electrode (150 mm long × approx. 6.3 mm dia.) that fits a #7 ACE-Thred™ port. The part number for replacement graphite rods is 935-00014.

To install, slide the O-ring onto the graphite rod and insert it into the port, immersing the desired length in the electrolyte.

Graphite rods are spectroscopic grade and unlikely to cause contamination initially, but they can adsorb substances. Reuse may lead to contamination if test solutions vary significantly.

Cell Counter Electrode: Optional Isolated Assembly

For isolation from the bulk solution, Gamry Instruments offers an Isolated Counter Electrode kit (Part Number 990-00194).

This kit includes a fritted isolation tube and 150 mm of platinum wire.

Diagram Description (Figure 3): A diagram of the Counter Electrode Isolation Tube, showing a glass tube with a frit at one end and a platinum wire extending through it, designed to isolate the counter electrode.

The fritted tube is inserted into a #7 ACE-Thred™ port. The platinum wire is slid into the tube, ensuring its lower end contacts the electrolyte. A bend in the wire helps maintain contact.

Reference Electrode and Bridge Tube

Overview and Terminology

Electrochemical measurements typically use a three-electrode potentiostat, with potentials measured against a reference electrode.

Directly placing a reference electrode in the test electrolyte can be problematic due to size, contamination from filling solution, or temperature effects on potential.

The Cell uses a bridge tube to position the reference electrode above the cell. The bridge tube, filled with electrolyte, provides a conductive path. Its tip, terminating in a glass frit, is convenient and adds minimal resistance.

A bridge tube differs from a Luggin capillary, which aims to place the sensing point closer to the working electrode surface.

Bridge Tube and Reference Electrode Assembly

Diagram Description (Figure 4): A diagram of the Reference Electrode Bridge Tube, showing a glass tube with a frit at one end, designed to hold a reference electrode and provide a conductive path to the cell electrolyte.

Assembly involves placing O-rings and ACE-Thred™ fittings on the bridge tube and reference electrode. Electrolyte is poured into the bridge tube, and the reference electrode is inserted. The bridge tube is then placed into a cell port and adjusted for height.

Steps for Assembly:

1. Place an O-ring and #7 ACE-Thred™ fitting on the bridge tube.
2. Place an O-ring and #11 ACE-Thred™ fitting on the reference electrode.
3. Pour electrolyte into the larger end of the bridge tube, leaving 2.5 cm headspace.
4. Insert the reference electrode tip-first into the bridge tube and tighten the #11 ACE-Thred™ fitting.
5. Place the smaller end of the bridge tube into a cell port.
6. Adjust the bridge tube height so its tip is in the electrolyte near the working electrode.
7. Tighten the bridge tube's #7 ACE-Thred™ fitting.

Bridge Tube and Reference Electrode: Maintenance and Care

Caution: Do not allow glass frits on the reference electrode or bridge tube to dry out, as they may crack, increasing solution flow.

Replacement frits with heat-shrinkable PTFE sleeves are included. Store bridge tube tips in electrolyte or appropriate solvent.

Caution: Do not use a plastic sleeve to cover the Bridge Tube's glass-frit tip unless the other side is covered with solvent or electrolyte. Drying out can cause cracking and irreproducible results.

To replace a frit:

1. Ensure the bridge tube is clean and dry.
2. Cut off the old frit with a sharp blade.
3. Warning: Cut away from your body to prevent injury.
4. Place a PTFE sleeve over the tube end.
5. Insert the new glass frit into the sleeve and heat to shrink the sleeve.
6. Warning: Heat guns can cause burns; be careful.
7. Trim the sleeve flush with the frit.

The reference electrode fill hole serves for refilling and venting. Keep it slightly open during normal use and closed when storing.

Spare Port

The Cell includes a spare 14/20 port that can be capped with a stopper. A vent hole may be needed in the stopper if gas is flowing into the cell and no other vent is available.

This port can also be used for system customization, such as adding corrosive agents or a pH electrode.

Addition of corrosive agents

Reactants can be added via the spare port to record baseline curves and analyze specific electrochemistry.

Temperature Sensing and Control

Temperature significantly affects chemical reaction rates. Measure or control cell temperature as needed.

Thermometer adapters (e.g., Ace part number 5028-26) can be used for temperature measurement.

For temperature control:

1. Use the jacketed cell body (Gamry part number 930-00041) with a circulating temperature-transfer fluid.
2. Connect the jacket to a recirculating constant-temperature bath.
3. Place a sensor in the spare port if the bath offers remote sensing (may require an adapter).
4. Gamry software can control the temperature bath via an RS-232 port in some cases.

Addition of a pH electrode

A pH electrode can be added using the spare port with an appropriate adapter.

Getting a Stir Bar into the Cell

A stir bar can be added through the spare port if forgotten during initial assembly.

Moving the Pieces About

The standard cell configuration may need adjustment for larger electrodes. Ports can accommodate various electrodes or adapters, with the 24/40 port being the largest.

Electrode Connections

Connect the Cell to a Gamry Instruments potentiostat as follows:

• Reference Electrode: White pin jack on the cell cable.
• Working Electrode: Green and blue leads from the cell cable. Clip blue and green leads separately for high currents.
• Counter Electrode: Red lead on the cell cable.

Ensure the long black lead (shield) does not touch other connections. Connecting it to earth ground (e.g., a water pipe) can reduce noise.

For very small currents, a metal enclosure (Faraday cage) connected to earth ground can further reduce noise. Connect the black lead to the Faraday shield.

Gamry's VistaShield™ is a Faraday cage designed for use with the Cell kit.

Tip: Always double-check cell connections.

Troubleshooting

Common problems include:

• Lack of connection between a cell lead and the electrolyte.
• Gas bubbles blocking electrode access to the electrolyte (e.g., on the working electrode face, in the counter electrode isolation tube, or in the reference bridge tube).
• Two electrodes shorting together.

This guide applies to potentiostatic experiments; galvanostatic experiments may show different symptoms.

Very small current or no current (no overload indication)

• Working electrode lead not connected properly.
• Gas bubble blocking the working electrode face.

Very small current or no current (with control amplifier overload)

• Counter electrode lead not connected properly.
• Counter electrode partially pulled out.
• Counter electrode isolation tube not filled with electrolyte.

Full-scale current and voltage, many overloads

• Reference electrode lead not connected properly.
• Working sense (blue) lead not connected properly.
• Incorrect experimental settings.
• Electrodes shorted together.
• Gas bubble in the Luggin capillary.

Large currents may require resurfacing or replacing the working electrode.

Noisy Cell Current—overloads may be present

• De-oxygenation gas still bubbling.
• High impedance in the reference electrode path.
• Gas bubble in the Reference Bridge Tube.
• Picking up external noise (use a Faraday cage).

Excess back pressure required to bubble deoxygenation gas

• No vent available for gas to escape.

Poor Experimental Reproducibility

• Test solution leakage under the PTFE Compression Gasket.
• Contamination of cell, solution, or working electrode surface.
• Contaminants entering from the graphite counter electrode.
• Inherent irreproducibility of the electrochemical system (e.g., localized corrosion).

Specifications

Cell

• Volume: 175 mL maximum, 125 mL minimum
• Port Types: One 24/40 standard taper ground-glass joint, Two 14/20 standard taper ground-glass joints, Two #7 ACE-Thred™ ports

Reference Electrode

• Size: 9 to 11 mm diameter (using the standard bridge tube)

Working Electrode

• Diameter: 7 to 9 mm (using the adapter supplied with the cell)
• Length: 50 mm minimum (using large cell volumes)

Index

The index lists key terms and their corresponding page numbers for easy reference.

• ACE-Thred™: 4, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 25
• borosilicate glass: 8
• bridge tube: 11, 17, 18, 19, 20, 25
• Bridge Tube: 5, 9, 17, 18, 20, 24
• calomel reference electrode: 18
• chemical compatibility: 5, 8
• counter electrode: 9, 11, 15, 16, 23, 24
• earth ground: 22
• Faraday cage: 13, 22, 24
• FETFE: 8, 9
• Gas Bubbler Tube: 13, 14, 15
• glass frit: 8, 9, 15, 16, 17, 19, 23
• graphite rod: 15, 16
• ground glass joints: 11
• Isolated Counter Electrode kit: 16
• Luggin capillary: 17, 24
• nylon: 8, 9
• O-ring: 8, 9, 14, 16, 18
• O-rings: 9, 17
• pH electrode: 5, 21
• platinum wire: 16
• polyethylene: 8, 15
• port: 8, 11, 14, 15, 16, 20, 21
• PTFE: 8, 9, 19, 24
• Pyrex®: 4, 8
• reference electrode: 11, 17, 18, 19, 20, 21, 23, 24
• ring stand: 11
• shipping damage: 9
• specifications: 5, 25
• stir bar: 21
• thermometer adapters: 20
• three-way valve: 15
• troubleshooting: 5, 23
• vacuum grease: 11
• vent: 8, 11, 14, 15, 19, 20, 24
• Viton®: 4, 8
• working electrode: 15, 17, 18, 22, 23, 24