Insights into electrocatalysis through in situ electrochemical surface-enhanced Raman spectroscopy

Electrocatalysis plays an essential role in sustainable energy conversion technologies such as fuel cells, water electrolysis, and the carbon dioxide reduction reaction that occurs at solid–liquid interfaces. However, due to the complexity of the respective electrochemical interfaces and trace amounts of interfacial species, researchers’ knowledge of these reaction mechanisms remains incomplete, limiting our ability to improve electrocatalytic performance. In situ electrochemical surface-enhanced Raman spectroscopy (EC-SERS) has proven to have appealing potential for the study of electrocatalytic reaction mechanisms because it can provide exceptionally sensitive fingerprint vibrational spectroscopic information about interfacial species and their interactions. This review offers insights into electrocatalysis through in situ EC-SERS. We begin with an introduction to the basic principles, substrate engineering, and the implementation of in situ EC-SERS for electrocatalysis, with an emphasis on capturing trace interfacial species and determining the capability of this technique. We then discuss fundamentals, still-debated mechanistic issues, as well as advanced applications of EC-SERS for mechanism studies of the fundamentally and practically important reactions in sustainable energy conversion technologies, to gain insights into electrocatalysis. Finally, we propose directions for the future development of in situ EC-SERS in catalysis. Through this review paper, we aim to attract greater attention to the use of in situ EC-SERS in catalysis studies and introduce versatile methodologies and techniques for catalytic studies that will result in superior performance. • In situ electrochemical surface-enhanced Raman spectroscopy (EC-SERS) can probe finger–printer spectroscopic information of interfacial species and their interactions to elucidate reaction mechanisms and reveal structure–performance relationships at the molecular or atomic level. • Elucidation of the reaction mechanisms and structure–performance relationships can guide the design of electrocatalysts and the manipulation of electric double layers to enhance electrocatalytic performance.