Challenges and Perspectives of Single-Atom-Based Catalysts for Electrochemical Reactions

Abstract

Single-atom catalysts (SACs) are emerging as the most promising catalysts for various electrochemical reactions. The isolated dispersion of metal atoms enables high density of active sites, and the simplified structure makes them ideal model systems to study the structure–performance relationships. However, the activity of SACs is still insufficient, and the stability of SACs is usually inferior but has received little attention, hindering their practical applications in real devices. Moreover, the catalytic mechanism on a single metal site is unclear, leading the development of SACs to rely on trial-and-error experiments. How can one break the current bottleneck of active sites density? How can one further increase the activity/stability of metal sites? In this Perspective, we discuss the underlying reasons for the current challenges and identify precisely controlled synthesis involving designed precursors and innovative heat-treatment techniques as the key for the development of high-performance SACs. In addition, advanced operando characterizations and theoretical simulations are essential for uncovering the true structure and electrocatalytic mechanism of an active site. Finally, future directions that may arise breakthroughs are discussed.

Heck Migratory Insertion Catalyzed by a Single Pt Atom Site

“…Poor dispersion and high interfacial tension of solid supports in the solvent limit the uniform distribution of the metal precursors. This increases the likelihood of the sintering of metals to a varied population of nanostructures, including atomic species, clusters, and nanoparticles. − Toward this end, we demonstrated the scCO 2 -assisted method to highly disperse Pt atoms on nitrogen-doped porous carbon (denoted as Pt 1 /NPC). The fabrication process is illustrated in Figure a.…”

Nanostructured single-atom catalysts derived from natural building blocks

“…98,103 Specifically, XANES can reveal details about the electron and oxidation states, while EXAFS offers more information on the chemical bonding, interatomic distance, and coordination number of the target element by combining wavelet transform (WT) and Fourier transform (FT)-EXAFS analysis. 89,104 Different XANES adsorption curves often show the central atoms with different coordination numbers or ligands, making it easy to identify SACs. Alternatively, XAFS can also be used in situ / operando to provide significant insights into the structural evolution of SACs under real catalytic conditions.…”

Understanding the Synergy between Fe and Mo Sites in the Nitrate Reduction Reaction on a Bio‐Inspired Bimetallic MXene Electrocatalyst

“…[19] In particular, the electronic structure and catalytic properties of MXenes are tunable by metal substitution in the lattice of the parent carbide, allowing for the generation of active sites tailored to a specific application, such as Co-substituted Mo-based MXene, Mo 2 CT x : Co (T x = O, OH, F surface terminations) for the hydrogen evolution reaction (HER). [20] An alternative synthetic approach to MXene-based single-atom catalysts (SACs) [21] is to rely on the use of MXenes as supports to confine atomicallydispersed late transition metals (Pt, Ru) to surface defects (metal vacancies) in the host MXene phases. [22] However, precise control over the speciation (SACs, dimers, trimers, clusters, etc.)…”