Structural design of metal catalysts based on ZIFs: From nanoscale to atomic level

Abstract

Abstract Ultrasmall metal nanoparticles (MNPs) and atomically dispersed metal sites (ADMSs) exhibit excellent catalytic activity and selectivity. However, they tend to aggregate into large particles during synthesis and catalysis due to high surface free energy. Aiming to break out of this dilemma, zeolite imidazolate frameworks (ZIFs) have proved to be ideal substrates for stabilizing the ultrafine metal nanostructures. The stabilizing mode includes confining MNPs inside their pore structures and converting intrinsic metal nodes into coordinately unsaturated metal sites (i.e., ZIF‐confined metal catalysts). Furthermore, various MNPs and ADMSs can also be immobilized into ZIF‐derived porous carbon through high‐temperature pyrolysis (i.e., ZIF‐derived carbon‐supported metal catalysts). In brief, ZIFs and their derivatives have gradually emerged as good platforms for designing metal catalysts at nanoscale and even atomic level. In this review, recent progress in the structural analysis and synthetic strategies of metal catalysts supported by ZIFs and their derivatives is presented. Besides, current challenges and future directions of atomically dispersed metal catalysts are discussed. This article will provide valuable insights into rational design of metal catalysts with exquisite nanostructure and high catalytic performance to meet further material requirements in the catalytic field.

Keywords

• single‐atom catalysts
• synthetic strategy
• ultrasmall metal nanoparticles
• zeolite imidazolate frameworks
• ZIF‐derived carbon