Unraveling the mechanism of hydrogen evolution reactions in alkaline media: recent advances in in situ Raman spectroscopy

Electrocatalytic water splitting for hydrogen production stands out among various hydrogen generation technologies due to its environmental friendliness and high efficiency. In alkaline media, the electrocatalytic hydrogen evolution reaction (HER) is a key step in the water splitting process. Developing high-performance electrocatalysts is crucial to reducing the energy consumption of water splitting. The HER process involves the decomposition of water molecules and the adsorption of reactive intermediates on the catalyst surface, and the in-depth study of this process requires the use of advanced characterization techniques. However, it is difficult to capture the real-time dynamic information of the catalytic process by traditional characterization techniques. Here, in situ Raman spectroscopy is an ideal tool to investigate the HER mechanism, which can monitor the dynamic changes in the catalytic process in real time. In this review, we first introduce the basic principles and research progress of in situ Raman spectroscopy. Then, we explore the role of this technique in exploring the interfacial water structure of catalysts and extend it to noble metal and transition metal-based catalysts to analyze the HER mechanism in depth. Finally, we prospect the future development of in situ Raman spectroscopy, emphasizing its important role in guiding the development of highly efficient catalysts as well as promoting the development of green hydrogen generation technologies.