Single-atom catalysts (SACs) have exhibited outstanding performance in electrocatalytic water splitting due to their maximal atomic utilization and excellent reaction kinetics. However, their loading is typically limited to below 2 wt% and tends to be non-uniform, which constrains further enhancement of catalytic performance and impedes detailed mechanistic investigations. In contrast, atomically thin materials (ATMs)—limited to one or a few atomic layers—feature layered structures and high specific surface areas that effectively prevent metal atom aggregation, thereby increasing loading capacity. Furthermore, ATMs possess abundant surface defects, accessible active sites, and uniform electronic and geometric structures, making them ideal supports for probing active sites and surface reaction pathways. Nevertheless, current research often centers on the metal atoms themselves, frequently neglecting the crucial role of the support materials in SAC systems.
This review underscores the importance of metal–support interactions in SACs@ATMs and proposes a design framework for developing high-performance electrocatalysts for water splitting. We first systematically summarize synthetic strategies for SACs@ATMs, with particular attention to methods enabling high metal loadings and industrial scalability. A comprehensive discussion of characterization techniques is also provided, which is vital for elucidating the coordination environments of catalytic active sites. Subsequently, we examine the applications and underlying mechanisms of SACs in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Finally, we discuss future directions and opportunities for SACs@ATMs in water electrolysis.
This review highlights that the interactions between metal atoms and their supports are critical determinants of the catalytic behavior of SACs@ATMs. Therefore, achieving a deep understanding and precise regulation of these interactions is essential for the rational design and optimization of next-generation electrocatalysts for water splitting.

The work titled “Single-Atom Catalysts Supported on Atomically Thin Materials for Water Splitting”, was published in Advanced Powder Materials (Available online on 24 July 2025).

DOI:https://doi.org/10.1016/j.apmate.2025.10033