Supported and coordinated single metal site electrocatalysts

The ever-increasing global environmental and energy crisis issues necessitate technological innovation, especially in the development of renewable energy-related devices, such as electrochemical energy conversion and storage technologies, including fuel cells, water electrolyzers, and CO₂ electrolyzers. Reliable and sustainable energy conversion devices are highly dependent on engineering of electrocatalysts. State-of-the-art electrocatalysts for these electrochemical conversion systems are usually platinum group metal (PGM)-based nanoparticles with high cost, which has sparked intensive research on atomically dispersed single metal site electrocatalysts for decreasing metal loadings and boosting catalytic efficiencies by taking advantage of their inherent electronic effects, quantum size effects, and metal-support interactions. In this review, we first introduce the concept of atomically dispersed single metal site electrocatalysts, including highlighting their key properties and synthesis strategies, followed by a discussion of the mutual metal-support interactions, and most importantly, how these factors correlate with catalytic properties. Next, the advances in synthetic strategies and characterization techniques for single metal site electrocatalysts are highlighted. Recent advances in single metal site electrocatalysts designs for applications in electrochemical conversion reactions are also presented. Finally, remaining challenges and a forward-looking perspective on this field of research are provided.