In-situ/operando Raman techniques for in-depth understanding on electrocatalysis

Recently, the electrocatalysis has attracted increasing attention for the sustainable development of society, which has been applied for energy harvesting/storage and pollution control. Therefore, various electrocatalysts have emerged over the past two decades to improve the efficiency and reduce the cost for commercialization. How-ever, a deep understanding of dynamical processes in the electrochemical reactions remains deficient, leading to the waste of effort in the design of electrocatalysts. As the reaction occurs on the surface of electrocatalyst, surface-sensitive technologies are essential to give an in-situ characterization for the dynamical process and guidance on the design of novel catalysts. Fortunately, in-situ/operando Raman technique can provide molecular -level fingerprint information on the surface of material, intermediates, and solvents under working conditions. This review elaborately summarizes recent advances of in-situ/operando Raman studies in probing different electrocatalytic systems. We systematically discuss the development, advantages, and configurations now available for applying these Raman techniques firstly. Then, the focus moves to their applications in five types of electrocatalytic reactions to gain a comprehensive understanding on the mechanisms. Finally, the challenges and perspectives on the future developments of in-situ/operando Raman techniques for electrocatalysis are presented.