Engineering Single Atom Catalysts to Tune Properties for Electrochemical Reduction and Evolution Reactions

Abstract

Electrocatalysis is important to the conversion and storage of renewable energy resources, including fuel cells, water electrolysers, and batteries. Engineering metal‐based nano‐architectures and their atomic‐scale surfaces is a promising approach for designing electrocatalysts. Single metal atom interactions with substrates and reaction environments crucially modulate the surface electronic properties of active metal centers, yielding controllable scaling relationships and transitions between different reaction mechanisms that improve catalytic activity. Single‐atom catalysts (SACs) allow activity and selectivity tuning while maintaining relatively consistent morphologies. SACs have well‐defined configurations and active centers within homogeneous single‐atom dispersions, producing exceptional selectivities, activities, and stabilities. Furthermore, SACs with high per‐atom utilization efficiencies, well‐controlled substrate compositions, and engineered surface structures develop single atom active sites for molecular reactions, enhancing mass activities. Recent developments in different metal‐based SAC nanostructures are discussed to explain their remarkable bi‐functional electrocatalytic activities and high mechanical flexibility, especially in the oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, hydrogen evolution reaction, and in battery applications. Existing barriers to and future insights into improving SAC performance are addressed. This study develops practical and fundamental insights on single atom electrocatalysts directed towards tuning their electrocatalytic activities and enhancing their stabilities.

Uneven Oxidation and Surface Reconstructions on Stepped Cu(100) and Cu(110)

“…Surface steps are commonly observed, significant defects on realistic surfaces. Given the atoms comprising step edges are undercoordinated, surface steps are considered active sites for heterogeneous catalysts due to their enhanced binding with reactant molecules, − improved bond-breaking activity, , capability to stabilize single atom catalysts , and change the stability of catalytically active phases . Besides catalytic applications, surface steps are also important sites for crystal growth and erosion, serving as sources and sinks for diffusing atoms and controlling atomic diffusion .…”

Insights into Heterogeneous Catalysts under Reaction Conditions by In Situ/Operando Electron Microscopy

“…This aspect is important considering the nanoscale-enhanced atomic diffusion, surface mobility, and surface interaction energies that contribute significantly to the low-temperature surface-mediated sintering of the nanoparticles or dispersion into clusters or single atoms. [282][283][284][285] Future development of the in situ/operando TEM and combined techniques will continue to play an increasingly important role not only in controlling or improving the existing catalysts for the various catalytic reactions, but also in designing or preparing new catalysts for advancing the cutting-edge areas of sustainable energy research and applications.…”

Altering Local Chemistry of Single‐Atom Coordination Boosts Bidirectional Polysulfide Conversion of Li–S Batteries

“…Single-atom catalysts (SACs) have recently emerged as a new frontier in the field of catalysis due to their remarkable catalytic capability and maximized atom utilization. [21][22][23][24] Distinct from those conventional heterogeneous catalysts in bulk or nanoparticle forms, SACs feature atomically dispersed metal centers immobilized on the supporting substrate, offering ideal platforms to establish relationship between active sites and catalytic mechanisms. Considering these advances, SACs have been widely explored in Li-S realm to date.…”