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selective and sensitive detection, rapid quantification of a huge variety of analytes, diagnostic tool, development of new methodologies and sensors, etc. [3].
The combination of two well-known analytical techniques, electrochemistry and spectroscopy, gives rise to spectroelectrochemistry (SEC) – an established scientific methodology. This hybrid technology offers researchers the best of both worlds by being able to record both an optical and an electrochemical signal at the same time to obtain new data [1]. This article begins with a spectroelectrochemistry definition and showcases its advantages in research, followed by new systems and solutions that make it easier to work on a multitude of spectroelectrochemistry applications.
What is spectroelectrochemistry?
Spectroelectrochemical methods are multi-response methods. They study the process of electrochemical reactions with simultaneous optical monitoring. Spectroelectrochemistry provides two individual signals from a single experiment, which is a very powerful feature to obtain critical information about the studied system. Moreover, the autovalidated character of spectroelectrochemistry confirms the results obtained by two different routes.
Find out more about this topic in our Application Note.
The spectroelectrochemistry principle is based on analyzing the interaction between a beam of electromagnetic radiation and the compounds involved in the electrochemical reactions. Variations in the optical and electrochemical signals provide insights into the progression of the electrode processes.
This analytical technique was developed in the 1960’s when Professor Theodore Kuwana worked with transparent electrodes to study a simultaneous process—measuring the charge and absorbance (concurrently) when a beam of light passes through the electrode [2]. These so-called «optically transparent electrodes» (OTEs) were developed to carry out the combined optical and electrochemical experiments. However, not all spectroelectrochemical configurations require transparent electrodes.
Since the first published paper on spectroelectrochemistry in 1964 [2], the number of works and investigations based on this technique has grown steadily (Figure 1).
Figure 1.
Spectroelectrochemistry publications have increased significantly since the technique’s discovery in the 1960’s (results of searching «Spectroelectrochem*» as a term in Scopus as of January 2025).
Spectroelectrochemistry allows researchers to collect molecular, kinetic, and thermodynamic information from the reactants, intermediates, and/or products involved in electron transfer processes. Thus, it is possible to perform spectroelectrochemical studies on a broad range of molecules and different processes including biological complexes, polymerization reactions, nanomaterial characterization, analyte detection, corrosion mechanisms, electrocatalysis, environmental processes, characterization of memory devices, and much more.
An array of spectroelectrochemical techniques to choose from: types of SEC
Different kinds of information are obtained depending on the spectral range used. The following graphic (Figure 2) is classified according to the combination of different electrochemical and spectroscopic methods. The general classification is based on the spectroscopic technique: ultraviolet (UV), visible (Vis), photoluminescence (PL), infrared (IR), Raman, X-ray, nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR).
Figure 2.
Spectroelectrochemistry (SEC) is the combination of spectroscopy and electrochemistry, shown here as the overlap between these two techniques.
For instance, UV/VIS spectroscopy provides molecular information related to the electronic levels of the molecules, the NIR region provides data associated with the vibrational levels, and the Raman spectrum provides very specific information about the structure and composition of the sample due to the fingerprinting characteristics of this technique (Figure 3).
Figure 3.
Diagram of the electromagnetic spectrum.
The main advantages of spectroelectrochemical techniques are summarized below:
- they simultaneously provide information obtained by two different techniques (electrochemistry and spectroscopy) in a single experiment
- qualitative studies and quantitative analyses can be performed
- high selectivity and sensitivity
- spectroelectrochemistry is used in several different fields due to its versatility
- new configurations facilitate the performance of spectroelectrochemical experiments, saving time, samples, costs, etc.
Significant advances have occurred in recent years regarding the design, development, and possibilities offered by instruments for working with spectroelectrochemical techniques. Also, the assemblies and the connections between products and accessories that facilitate the use of this equipment have improved, contributing to make research and experiments in this field easier and more affordable.
The evolution of spectroelectrochemical instrumentation
Traditionally, the configuration for spectroelectrochemical analysis consists of two instruments: one spectroscopic instrument and the other for electrochemical analysis (Figure 4). Both instruments are connected independently to the same spectroelectrochemical cell and are usually not synchronized. In addition, each instrument is controlled by a different (and specific) software, so two programs are needed to interpret each signal as well as yet another external software for processing and analyzing the data obtained by the first two programs. Finally, it must be considered that synchronization is not guaranteed, making the performance of experiments and tests with this configuration slow, complex, and costly.
Figure 4.
This detached spectroelectrochemical setup displays the complexity of the software and programs used, showing that different systems are not able to obtain actual synchronized electrochemical measurements and data.
Metrohm DropSens took this opportunity to create something that did not exist before—revolutionizing state-of-the-art spectroelectrochemistry: the SPELEC line of instruments (Figure 5). These are fully integrated, synchronized solutions that offer researchers much more versatility. The devices include all of the components needed to work with spectroelectrochemical techniques in a simple way and in a single system with a (bi)potentiostat/galvanostat, the light source, and the spectrometer (depending on the selected spectral range).
Figure 5.
The SPELEC systems from Metrohm DropSens consist of one device and one software—a fully integrated, easy-to-use, practical SEC setup for researchers.
These designs and configurations simplify the work, processes, and spectroelectrochemical measurements as well because only a single system and a single software are needed. In the case of the SPELEC solution, its advanced dedicated software (DropView SPELEC) is a specific program that controls the instrument, obtains the electrochemical and spectroscopic signals simultaneously, and also allows users to process and analyze the data together in a single step. It’s really that simple!
The future of spectroelectrochemistry: SPELEC systems and software
One instrument and one software: Metrohm DropSens SPELEC has everything you need for your spectroelectrochemical experiments while saving valuable time and laboratory space. SPELEC instruments offer the combinations of electrochemistry and UV-Vis, Vis-NIR, or even Raman spectroscopy in a single measurement with several different instrument options available (see below). Everything is integrated which allows more tests in less time, multiple spectra, a full range of accessories, and research flexibility with the different configurations offered.
Multiple options are available depending on the spectral range needed:
SPELEC: 200–900 nm (UV-VIS)
SPELEC 1050: 350–1050 nm (VIS-NIR)
SPELEC NIR: 900–2200 nm (NIR)
SPELEC RAMAN: 785 nm, 638 nm, or 532 nm laser
DropView SPELEC is a dedicated and intuitive software that facilitates measurement, data handling, and processing. With this program, you can display electrochemical curves and spectra in real time and follow your experiments in counts, counts minus dark, absorbance, transmittance, reflectance, or Raman shift. As far as data processing is concerned, DropView SPELEC offers a wide array of functions including graph overlay, peak integration and measurement, 3D plotting, spectral movie, and more.
Testimonial from the University of Burgos on the integrated SPELEC system from Metrohm DropSens.
SPELEC instruments are very versatile, and although they are dedicated spectroelectrochemical instruments, they can also be used for electrochemical and spectroscopic experiments. They can be used with any type of electrodes (e.g., screen-printed electrodes, conventional electrodes, etc.) and with different spectroelectrochemical cells. Optical and electrochemical information is obtained in real time/operando/dynamic configuration.
Find out more in our blog post.
Simplifying spectroelectrochemistry setups with intuitive and user-friendly cells
Multiple spectroelectrochemistry applications
The characteristics of spectroelectrochemistry allow constant development of new applications in several different fields. Read on below to discover the capabilities of this technique (click to expand each section).
study of the properties and structure of different compounds, analysis of kinetic reactions, determination of electron transfer capacity, etc. [4].
evaluation of protective films as corrosion inhibitors, determination of electrode stability and reversibility, monitoring of layer and sublattice generation, improvement of protective properties of coating materials, etc.
monitoring of exchange and discharge cycles, determination of oxidation/reduction levels, characterization of new electrolytes for batteries, understanding of doping and splitting processes in solar cells, etc.
characterization and comparison of the electrocatalytic activity of different catalysts, identification of intermediate species and their structural changes, elucidation of the reaction mechanism, etc. [5].
study of biological processes, characterization of molecules used in biotechnology, biochemistry or medicine, determination of antioxidant activity, etc.
identification and quantification of pesticides, dyes, and pollutants, monitoring of degradation and filtration processes, etc. [6].
characterization of new materials for memory devices, comparison of minerals, identification of pigments, oils, and pastes, etc.
Learn even more about spectroelectrochemistry application possibilities by downloading our free Application Book.
Your knowledge take-aways
Catalog: SPELEC line portfolio
Blog post: Simplifying spectroelectrochemistry setups with intuitive and user-friendly cells
Spectroelectrochemistry Application Book
On-demand webinar: Spectroelectrochemistry in action: Live experiments
References
[1] Kaim, W.; Fiedler, J. Spectroelectrochemistry: The Best of Two Worlds. Chem. Soc. Rev. 2009, 38 (12), 3373. DOI:10.1039/b504286k
[2] Kuwana, T.; Darlington, R. K.; Leedy, D. W. Electrochemical Studies Using Conducting Glass Indicator Electrodes. Anal. Chem. 1964, 36 (10), 2023–2025. DOI:10.1021/ac60216a003
[3] Martín-Yerga, D.; Pérez-Junquera, A.; González-García, M. B.; et al. Quantitative Raman Spectroelectrochemistry Using Silver Screen-Printed Electrodes. Electrochimica Acta 2018, 264, 183–190. DOI:10.1016/j.electacta.2018.01.060
[4] Perez-Estebanez, M.; Cheuquepan, W.; Cuevas-Vicario, J. V.; et al. Double Fingerprint Characterization of Uracil and 5-Fluorouracil. Electrochimica Acta 2021, 388, 138615. DOI:10.1016/j.electacta.2021.138615
[5] Rivera-Gavidia, L. M.; Luis-Sunga, M.; Bousa, M.; et al. S- and N-Doped Graphene-Based Catalysts for the Oxygen Evolution Reaction. Electrochimica Acta 2020, 340, 135975. DOI:10.1016/j.electacta.2020.135975
[6] Ibáñez, D.; González-García, M. B.; Hernández-Santos, D.; Fanjul-Bolado, P. Detection of Dithiocarbamate, Chloronicotinyl and Organophosphate Pesticides by Electrochemical Activation of SERS Features of Screen-Printed Electrodes. Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 2021, 248, 119174. DOI:10.1016/j.saa.2020.119174
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