Strategic Defect Engineering of Metal–Organic Frameworks for Optimizing the Fabrication of Single‐Atom Catalysts

Abstract

Single-atom catalysts (SACs) have garnered enormous interest due to their remarkable catalysis activity. However, the exploitation of universal synthesis strategy and regulation of coordination environment of SACs remain a great challenge. Herein, a versatile synthetic strategy is demonstrated to generate a series of transition metal SACs (M SAs/NC, M = Co, Cu, Mn; NC represents the nitrogen-doped carbon) through defect engineering of metalorganic frameworks (MOFs). The interatomic distance between metal sites can be increased by deliberately introducing structural defects within the MOF framework, which inhibits metal aggregation and consequently results in an approximately 70% increase in single metal atom yield. Additionally, the coordination structures of metal sites can also be facilely tuned. The optimized Co SAs/NC-800 exhibits superior activity and excellent reusability for the selective hydrogenation of nitroarenes, surpassing several state-of-art non-noble-metal catalysts. This study provides a new avenue for the universal fabrication of transition metal SACs.

Homogeneity of Supported Single‐Atom Active Sites Boosting the Selective Catalytic Transformations

“…[215] Co SAs/NC-800 (the pyrolysis temperature of 800 °C) is also studied for the selective hydrogenation of nitroarenes, which exhibits superior activity and reusability. [194] Co SAs/NC-800 achieve a high yield of aniline (99.8%) in aqueous solution under 5 bar H 2 , with a TOF of 18.2 h −1 . But Co NPs/NC-800 only account for a yield of 44.7% under the same condition (Figure 11i).…”

“…h) EXAFS fitting and i) catalytic results of Co SAs. Reproduced with permission [194]. Copyright 2021, Wiley-VCH.…”

Atomically-dispersed NiN4–Cl active sites with axial Ni–Cl coordination for accelerating electrocatalytic hydrogen evolution

“…[16][17][18] At present, the strategies to regulate the SAC coordination environment mainly include changing the coordination atom species, increasing or decreasing the coordination number of the active center, heteroatom interaction within the support, and introducing the synergetic interaction between neighboring metal monomers. [19][20][21] However, most of the reported regulation of SACs is mainly carried out in the plane and the study of axial coordination is rarely proposed. 22,23 Chen et al 24 achieved coordination at the Fe site by chelating the Fe precursor with an O-doped carbonaceous carrier, preparing atom-dispersed FeN 4 -O active sites with axial Fe-O coordination.…”

Single-Atom Nanozymes: Fabrication, Characterization, Surface Modification and Applications of ROS Scavenging and Antibacterial

“…After years of development, SACs are defined as a novel catalyst in which catalytically active isolated metal atoms are immobilized on supports [ 25 ]. They combine the advantages of homogeneous catalysis and heterogeneous catalysis [ 26 ], and SACs possess the maximized atom utilization, unsaturated coordination of active sites, and adjustable electronic properties, which make them a hot research direction in the field of catalysis [ 27 , 28 , 29 ]. Meanwhile, the high atom utilization rate can also reduce the production cost of SACs [ 30 ] and the potential toxic and side effects of metal ions [ 31 , 32 ].…”