Contents 

What is Spectro-Electrochemistry?

Where is Spectro-Electrochemistry applied?

Application Note: Spectro-Electrochemistry of Methyl Viologen

How to Create a Spectro-Electrochemistry Solution Package: 

Item 1: Electrochemistry Part: The Potentiostat / Galvanostat  

          Electrochemistry Software for Spectroscopy Analysis: PSTrace from PalmSens

Item 2: A Spectro-Electrochemistry Cell Kit and Auxiliary Cable

Item 3: Spectrometer, Light-Source and Optical Bench Options

           Spectro-EC Kit for UV/Vis Analysis
           Spectro-EC Kit for UV/Vis - NIR Analysis
           Spectro-EC Kit for Flourescence Analysis
           Spectro-EC Kit for Raman Analysis

Spectro-Electrochemisty Resources

 What is Spectro-Electrochemistry?

Scientific methods can deliver detailed information about a molecule, solution, or reaction, however, a single method will only provide a limited amount of information based on a single interaction, for example, light absorption, oxidation at an electrode, change of mobility, or movement of mass in an electric field. For this reason, scientists try to create hyphenated techniques that allow observing the same system in real-time when efficiently combining analytical, chromatography based, electro-analytical or spectroscopic techniques. Another such hyphenated technique is spectro-electrochemistry, where electrochemical reactions or products are characterized by electrochemical techniques, e.g., cyclic voltammetry when synchronized in real time with spectroscopy methods, e.g., UV-VIS, VIS-NIR, Fluorescence and Raman. During the past two decades, the electrochemical and optical instruments become more compact and more economical. The information both techniques deliver is complementary as well. For example, while electrochemistry provides insights for the kinetics of a particular reaction, an unstable product (for example, a radical ion with limited half-life during redox reactions) of electrochemical oxidation can be detected by spectroscopy before it decays.

 Where is Spectro-Electrochemistry applied?

Historically, Spectro-electrochemistry has been used to study: Electrode surface phenomena, Reaction kinetics and mechanisms, Adsorbates, and products as a function of applied potential, Complex electrode reaction stoichiometries, and Diffusion coefficients of redox species. For example, UV-Vis Spectro-electrochemistry helps to characterize compounds and materials, determines concentrations and different parameters such as absorptivity coefficients, diffusion coefficients, formal potentials, or electron transfer rates. Whereas Infrared Spectro-electrochemistry has applications in the study of conducting polymers, redox-active organic molecules in solution, inorganic or organometallic complexes, as well as being often used in mechanistic studies and electrocatalysis. While there are numerous applications for this technique the main ones includes:

     - Bioelectrochemistry: Studying biological processes
     - Energy storage: Monitoring discharge and exchange cycles
     - Electrocatalysis: Characterizing catalysts
     - Environment: Identifying and quantifying pollutants, dyes, and pesticides
     - Redox polymer processes: Studying redox-active organic molecules in solution
     - Organometallic reactions: Studying inorganic or organometallic complexes

 Application Note: Spectro-Electrochemistry of Methyl Viologen

Methyl Viologen (MV) is also known as paraquat. It is used as an herbicide, but due to its toxicity for humans and scientific studies showing links between methyl viologen and Parkinson’s disease it has lost popularity. Methyl viologen’s toxicity is based on its redox chemistry.

This oxidation can be triggered electrochemically at a platinum electrode. As mentioned above MV2+ is colorless while MV+ is blue and accordingly is absorbing in the visual spectrum. Thus MV+ can be produced by electrochemical methods while being detected by UV/VIS spectroscopy. These spectro-electrochemical measurements could be applied to measure the kinetics of the oxidation. A typical chronoamperometry measurement at a constant voltage of (-0.85V) can trigger the oxidation mentioned above. The reduction of the colorless ion MV²⁺ leads to the blue radical ion MV⁺. Figure below shows the three spectra recorded combining spectroscopy and electrochemistry measurement in real-time. Thus, at -0.85V as the MV²⁺ is getting converted into MV²⁺ the decrease in concentration is represented by the decrease in characteristic UV-Vis absorbance at 200 nm along with the increase in absorbance round 390 and 600 nm representing the increasing MV⁺ concentration.

 How to Create a Spectro-Electrochemistry Solution Package 

 Item 1: Electrochemistry Part: The Potentiostat / Galvanostat

Spectro-Electrochemistry is usually a low current measurement. It requires electrochemistry techniques such as cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The important thing to be noted here is the capability of the potentiostat to trigger analog signals to the spectrometer and simultaneously plot the aquired spectroscopy signals from the spectrometer. BASi provides exactly the same with its PalmSens potentiostats such as  PalmSens 4, EmStat4X, and MultiPalmSens 4. Our ideal option here is EmStat4X LR equipped with auxiliary port, blue tooth connectivity (for glove-box measurements) and a specially added low current range of 1 nA to capture and plot extremely low currents (up to low pA) from side-reactions and radicals. The Potentiostat / Galvanostat also has a variety of optional features such as IR-compensation and EIS.

 Electrochemistry Software with Trigger & Plot Capability for Spectroscopy Analysis: PSTrace from PalmSens

The PSTrace software in our PalmSens Potentiostat has the capacity to provide external triggers at various stages of a measurement to an external device like Stirrer, pump, quartz crystal micro-balance or in this case to start and capture a scan on Avantes Spectrometer in real time. More information about our PSTrace is easily obtained here. Our YouTube video library to learn PSTrace summary is also a great educational resource for beginners.

 

 Item 2: A Spectro-Electrochemistry Cell Kit and Auxiliary Cable

Spectro-EC cell with Electrodes:

Cell Specifications：8 mm × 6.5 mm × 1 mm

Features: Shaped like a cuvette, surrounded by light. Made of full quartz melt with PTFE lid.

Application: Suitable for electrochemical testing in the process of in situ UV – visible spectroscopy, fluorescence spectroscopy and other spectral signal response.

Matching electrode: Platinum mesh electrode as the working electrode, the platinum wire electrode as Counter electrode, the silver/silver chloride electrode as the reference electrode.

Methyl Viologen solution turning blue at the platinum mash due to the -0.85V constant potential applied by the Potentiostat.

Other Spectro-EC Cell Options

Batch flow type Spectro-EC Cell options are available below. Each Spectro-EC cell kit includes a Pt / gold mini-grid, a thin layer quartz glass cell, a teflon lid with holes, a purging tube, and platinum counter electrode.

     - EF-1350: Spectro-EC cell kit with Pt mini-grid (1 mm path length)
     - EF-1362: Spectro-EC cell kit with Pt mini-grid (0.5 mm path length)
     - EF-1351: Spectro-EC cell kit with Au mini-grid (1 mm path length)
     - EF-1363: Spectro-EC cell kit with Au mini-grid (0.5 mm path length)

ADVANCED OPTIONS: More advanced flow-based Spectro-EC Cell kits are also available from the options below. Please contact us to add more customization options in advanced accessory option.

Connector Cable to Connect PalmSens Potentiostat to an Avantes Spectrometer: 

PALM-CBL-AUX-AVAN: BASi provides a direct plug-n-play connector cable that allows TTL or analog triggering between PalmSens potentiostats and Avantes Spectrometers (UV/Vis, Vis NIR or even Raman). The users can automatically trigger the spectrometer from the software without any manual intervention using either of these options to trigger the spectrometer for absorbance, transmission, reflectance or any other spectrosopic data as the EC measurements are taken in real-time.


 

 Item 3: Spectrometer, Light-Source and Optical Bench Options

 MF-SPEC-ECKIT: Spectro-EC Kit for UV/Vis Analysis

The MF-SPEC-ECKIT is a customized spectrometer kit for our customers wanting to expand their electrochemical research with UV-Vis Spectroscopy. This kit will allow users to conduct fully synchronous and in-situ analysis for electrochemistry along with UV-Vis Spectroscopy in the wavelength range of 200-1100 nm. The kit is fully detachaeble and also allows users to conduct “independent” measurements for electrochemistry and spectroscopy. The users can select the potentiostat / galvanostat as well as the Spectro-EC cells of their choice to complete the entire spectro-electrochemistry set-up. The PSTrace software from PalmSens will show the hybridized curve for both measurements. The kit is fully equipped with deuterium-halogen light source, optical bench, set of fiber optics cables, a cuvette holder (10 mm path) for dark-light subtraction, and more. More information is summarized in our Technical Specification Sheet.

 MF-SPEC-ECKIT-2: Spectro-EC Kit for UV/Vis - NIR Analysis

The MF-SPEC-ECKIT-2 is a customized Spectro-Electrochemistry Kit made for our customers wanting to expand their electrochemical research with Vis-NIR spectroscopy. This kit will allow users to conduct fully synchronous in-situ analysis for electrochemistry hybridized with UV-Vis + NIR Spectroscopy in the full wavelength range of 200-2500 nm. The PSTrace software from PalmSens can show one complete Spectro-EC curve combined for both UV-Vis and NIR in full range. Customizations options are available for flow cell type application using a platinum, gold and carbon as working electrodes. Batch cell type analysis is possible using a platinum or gold mesh electrode as a working electrode as listed in our section above for Spectro-EC cell options. More information is summarized in our Technical Specification Sheet.

 MF-SPEC-ECKIT-3: Spectro-EC Kit for Flourescence Analysis

The MF-SPEC-ECKIT-3 is a highly customized Spectro-EC kit for Fluorescence based applications. The kit is equipped with our newly launched AvaSpec-ULS2048x64TEC-EVO spectrometer which is an updated version with improved electronics and cooling. The back-thinned detector is equipped to provide an elevated level of sensitivity in the UV and IR regions. The kit is equipped with AvaLight-HPLED light source to produce continuous or pulsed spectral output at different wavelengths. It also has an SMA-905 connector to connect fiber optics and come with a 5V/1.6A power supply. A specially designed direct attach fluorescence cuvette holder is used in the kit where excitation and emission signals are oriented at perpendicular 90° angle to each other. The user is expected to provide information on the excitation wavelength that is needed for the measurement. More information is summarized in our Technical Specification Sheet.

 MF-SPEC-ECKIT-4: Spectro-EC Kit for Raman Analysis

The MF-SPEC-ECKIT-4 is a customized Spectro-Electrochemistry Kit made for our PalmSens customers wanting to expand their electrochemical research with Raman spectroscopy. This kit will allow users to conduct fully synchronous in-situ analysis for electrochemistry hybridized with Raman Spectroscopy using our new AvaSpec HERO Spectrometer (788-1020 nm) for detection. Such a high end cooled back-thinned detector with low-noise electronics, and an optical bench with high numerical aperture results in excellent signal to noise, dynamic range, and higher quantum efficiency in NIR region. Also included is our AvaLaser 785 (included: 785 nm laser safety goggles) and a high-end “Panorama Light Software” for spectroscopic data evaluation featuring 2D/3D data visualization, searching in libraries, archiving in spectral libraries, and more. The kit is also equipped with tight cuvette holder for use with Raman probe of AvaLaser785 with an adjustable gold coated mirror for signal collection. More information can be obtained on our Technical Specification Sheet.

 Spectro-Electrochemisty Resources: 

PalmSens 4 Series
EmStat4X Series
PSTrace Software
Spectro-Electrochemistry Cell Options
Advanced flow-based Spectro-Electrochemistry Cell Options
Spectro-electrochemistry Kits and Packages

EC Applications Applications Support 

Posted August 16, 2024