Defect‐Based Single‐Atom Electrocatalysts

Abstract

Single‐atom catalysts (SACs) have attracted great attention owing to their maximum atomic utilization and high catalytic performance in electrochemical reactions. But the synthesis of SACs is not easy due to large surface energies of single atomic metal sites which often lead to their aggregation. The defects on supports can serve as anchor sites to stabilize single metal atoms and prevent them from aggregation, which has become an effective method to fabricate SACs. This review summarizes the meaningful findings about the defects on supports stabilizing single metal atoms, and their applications in electrocatalytic reaction. Various defects, including the intrinsic defects or heteroatom doping of carbon‐based materials, cation or anion vacancies of metal compound supports, and other defects (step edges, lattice defects, and caves), are comprehensively summarized, and the effects of defects on designing SACs are discussed. Although there are still many challenges to fully explore the SACs, it is believed that the newly established defect sites stabilized single atoms mechanism will be helpful for designing and fabricating highly powerful single atomic electrocatalysts for practical applications.

Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion

“…Influencing the local atomic environment through factors including the location (edge or in‐plane), surrounding heteroatoms, grafting additional ligands onto the center, and creating dual‐metal sites have been demonstrated to be effective methods to enhance the activity of SACs for many energy‐related electrocatalytic reactions. Although some excellent review articles have focused on the importance of metal–support interactions or defects for the rational design of SACs, the effect of the local coordination environment on the electrochemical performance of carbon‐based heteroatom coordinated SACs has not been systematically summarized.…”

Fe atoms anchored on defective nitrogen doped hollow carbon spheres as efficient electrocatalysts for oxygen reduction reaction

“…Strategies to improve the performance of single-atom catalysts are widely investigated such as increasing the density of active sites, enhancing the intrinsic activity of catalyst by the construction of bi-metal or tri-metal active sites or regulation of coordination environment of active sites [6,[14][15][16][17]. Introduction of intrinsic defects is identified as effective method to tune the coordination structure of single active site [18][19][20][21]. Recently, Yao and co-workers demonstrate that defective graphene or carbon capsules with amounts of structural defects provide unique coordination environment for metallic species that exhibits more excellent electrocatalytic activity than that of M-N/C catalysts due to the high spin and charge densities [22][23][24][25][26].…”

Recent Advances in Phosphorus‐Coordinated Transition Metal Single‐Atom Catalysts for Oxygen Reduction Reaction

“…However, limited by high cost and scarce resources, large‐scale application of Pt is unrealistic. In recent years, single‐atom catalysts (SACs) have attracted considerable attention due to their maximum atomic efficiency and high catalytic activity [6–7] . Nitrogen‐coordinated transition metal sites (M−N x , M=Fe, Co, Ni, Mn, etc.)…”