Unraveling electrocatalyst reaction mechanisms in water electrolysis: <i>In situ</i> Raman spectra

Electrocatalysis is crucial for sustainable energy solutions, focusing on energy harvesting, storage, and pollution control. Despite the development of various electrocatalysts, understanding the dynamic processes in electrochemical reactions is still limited, hindering effective catalyst design. In situ Raman spectra have emerged as a critical tool, providing molecular-level insights into surface processes under operational conditions and discussing their development, advantages, and configurations. This review emphasizes new findings at the catalyst–electrolyte interface, especially interface water molecule state, during the hydrogen evolution reaction and oxygen evolution reaction in recent years. Finally, the challenges and future directions for in situ Raman techniques in electrocatalysis are discussed, emphasizing their importance in advancing understanding and guiding novel catalyst design.