Recent advances in hydrogen spillover and reverse hydrogen spillover for the two-dimensional materials

The efficient hydrogen evolution reaction (HER) is crucial for clean hydrogen energy production. Two-dimensional (2D) materials, as promising non-noble metal HER catalysts, often suffer from limitations such as insufficient active sites and low electron transport efficiency. This review focuses on the phenomena of hydrogen spillover and reverse hydrogen spillover within 2D material systems, systematically examining recent research progress on how these phenomena enhance HER performance. We discuss the fundamental principles and catalytic mechanisms by which hydrogen spillover and reverse hydrogen spillover optimize hydrogen adsorption/desorption kinetics. Interface engineering strategies, including the construction of heterointerfaces, tuning of work function difference, and strengthening of metal-support interactions are summarized as effective approaches to promote (reverse) hydrogen spillover effects, thereby enhancing catalytic activity and stability. Finally, we outline key verification methods, including electrochemical measurements, in situ spectroscopies, and density functional theory (DFT) calculations. This review aims to provide a theoretical foundation and directional guidance for the design and development of efficient and stable 2D HER electrocatalysts leveraging spillover effects, contributing to the advancement of the green hydrogen economy.