Researchers have developed an innovative technique known as in situ electrochemical surface-enhanced Raman spectroscopy (EC-SERS), which significantly enhances the ability to detect interfacial species during electrocatalytic reactions. This breakthrough, detailed in a comprehensive review published in the journal eScience, reveals intricate reaction mechanisms that were previously obscured.
The review, released in 2025, outlines how EC-SERS amplifies Raman signals through plasmonic nanostructures, enabling real-time observation of dynamic interfacial species under operational conditions. By identifying key vibrational signals of trace and transient species, the technique elucidates the relationship between electrocatalyst properties and interfacial environments, which are critical for reactions related to fuel cells, water electrolysis, and carbon dioxide reduction.
Localized surface plasmon resonance (LSPR) effects on gold, silver, and copper nanostructures generate intense electromagnetic “hotspots,” which enhance Raman signals by several orders of magnitude. This enables the detection of species at the monolayer level, offering unprecedented insights into the molecular interactions that govern electrocatalytic performance.
The authors of the review emphasize that EC-SERS provides a molecular-level clarity that was previously unattainable in operando electrocatalysis. They note that subtle shifts in vibrational modes can track the reorganization of electrocatalytic surfaces, the emergence or disappearance of reaction intermediates, and how interfacial water and cations influence electron-proton transfer.
EC-SERS has been effectively employed to differentiate between associative and dissociative pathways in oxygen reduction on platinum single crystals. Additionally, it has revealed valence-state-dependent hydrogen-evolution kinetics on ruthenium surfaces, as well as bifunctional interactions in platinum-based alloys that drive alkaline hydrogen-oxidation activity. These case studies illustrate the technique’s capability to provide detailed insights into the structural evolution of interfacial water, including its hydrogen-bond network and orientation.
The review also integrates EC-SERS with density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. This combination correlates vibrational frequencies with adsorption energies, reaction barriers, and the structure of the electric double layer, linking electronic properties to electrocatalytic performance across major clean-energy reactions.
The authors assert that this methodology opens strong avenues for rational design in electrocatalysts and electric double layers, particularly for hydrogen production and CO2 utilization. By revealing how binding energies and interfacial solvation influence critical steps, researchers can fine-tune electrocatalyst composition, morphology, and active-site configuration.
Future advancements in EC-SERS may further enhance its capabilities, including broadening potential windows, integrating multimodal spectroscopy, improving spatial resolution, and employing machine learning for spectral interpretation. Such developments could establish EC-SERS as a standard diagnostic tool for operando catalysis, thereby accelerating the development of efficient and durable energy-conversion systems necessary for a low-carbon future.
This work was supported by the National Natural Science Foundation of China and other institutions, reflecting a collaborative effort in advancing research in energy technologies. The findings from this study are set to contribute significantly to the field of electrochemistry and beyond, encouraging further exploration and innovation in sustainable energy solutions.
