Single-Atom Catalysts across the Periodic Table

Abstract

Isolated atoms featuring unique reactivity are at the heart of enzymatic and homogeneous catalysts. In contrast, although the concept has long existed, single-atom heterogeneous catalysts (SACs) have only recently gained prominence. Host materials have similar functions to ligands in homogeneous catalysts, determining the stability, local environment, and electronic properties of isolated atoms and thus providing a platform for tailoring heterogeneous catalysts for targeted applications. Within just a decade, we have witnessed many examples of SACs both disrupting diverse fields of heterogeneous catalysis with their distinctive reactivity and substantially enriching our understanding of molecular processes on surfaces. To date, the term SAC mostly refers to late transition metal-based systems, but numerous examples exist in which isolated atoms of other elements play key catalytic roles. This review provides a compositional encyclopedia of SACs, celebrating the 10th anniversary of the introduction of this term. By defining single-atom catalysis in the broadest sense, we explore the full elemental diversity, joining different areas across the whole periodic table, and discussing historical milestones and recent developments. In particular, we examine the coordination structures and associated properties accessed through distinct single-atom−host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis, revealing trends in element-specific evolution, host design, and uses. Finally, we highlight frontiers in the field, including multimetallic SACs, atom proximity control, and possible applications for multistep and cascade reactions, identifying challenges, and propose directions for future development in this flourishing field.

Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

“…67 This type of study would cultivate a better understanding of OER catalysis from a comprehensive perspective, and furthermore would eventually bridge the gap between heterogeneous and homogeneous catalysis. [83][84][85] As described above, recent in situ and operando characterization studies captured the oxidation state of the active site and surface intermediate during the OER. The experimental evidence in Fig.…”

Single‐Atom Catalysts: A Sustainable Pathway for the Advanced Catalytic Applications

“…This process has gained enormous advancement by the advent of nanoscience and nanotechnology, more recently has found a revolutionary approach in the development of single‐atom catalysts (SACs). [ 15 ] In 2003, Saltsburg and Flytzani‐Stephanopoulos investigated Au and Pt in an ionic forms which were strongly associated with the surface of ceria and responsible for the water‐gas shift reaction. They reported that Pt or Au nanoparticles on the surface of ceria did not participate in the catalysis, the ionic form of Au or Pt on the surface of ceria has functioned as SACs.…”

Ligand-Metal Charge Transfer Induced via Adjustment of Textural Properties Controls the Performance of Single-Atom Catalysts During Photocatalytic Degradation

“…Single-atom catalysts (SACs) have recently emerged as a new class of materials bridging the gap between the homogeneous and heterogeneous catalysis worlds. [1][2][3] These materials represent the utmost utilization of precious metals, while offering more facile preparation, handling, and recovery compared to traditional catalytic systems. 4,5 Due to the unsaturated coordination of the active center as well as quantum and support effects, over the past few years SACs were improved to show extraordinary catalytic activity and selectivity toward specific products in important transformations such as hydrogenation, oxidation, carbon-carbon coupling, water-gas-shift, and electrosynthesis.…”