As one of the most important families of porous materials,metal–organic frameworks(MOFs)have well-defined atomic structures.This provides ideal models for investigating and understanding the relationships between str...As one of the most important families of porous materials,metal–organic frameworks(MOFs)have well-defined atomic structures.This provides ideal models for investigating and understanding the relationships between structures and catalytic activities at the molecular level.However,the active sites on the edges of two-dimensional(2D)MOFs have rarely been studied,as they are less exposed to the surfaces.Here,for the first time,we synthesized and observed that the 2D layers could align perpendicular to the surface of a 2D zeolitic imidazolate framework L(ZIF-L)with a leaf-like morphology.Owing to this unique orientation,the active sites on the edges of the 2D crystal structure could mostly be exposed to the surfaces.Interestingly,when another layer of ZIF-L-Co was grown heteroepitaxially onto ZIF-L-Zn(ZIF-L-Zn@ZIF-L-Co),the two layers shared a common b axis but rotated by 90°in the ac plane.This demonstrated that we could control exposed facets of the 2D MOFs.The ZIF-L-Co with more exposed edge active sites exhibited high electrocatalytic activity for oxygen reduction reaction.This work provides a new concept of designing unique oriented layers in 2D MOFs to expose more edge-active sites for efficient electrocatalysis.展开更多
基金the support from the National Natural Science Foundation of China(grant nos.21975148,21875149,21835002,21875140,and 21773146)the Fundamental Research Funds for the Central Universities+3 种基金the Research Funds of Shaanxi Normal University,Shanghai Natural Science Fund(no.17ZR1418600)ChEM,SPST of ShanghaiTech University(no.EM02161943)the Swedish Research Council Formas(no.2020-00831,Z.H.)the University of Calgary’s Canada First Research Excellence Fund Program,the Global Research Initiative in Sustainable Low Carbon Unconventional Resources.
文摘As one of the most important families of porous materials,metal–organic frameworks(MOFs)have well-defined atomic structures.This provides ideal models for investigating and understanding the relationships between structures and catalytic activities at the molecular level.However,the active sites on the edges of two-dimensional(2D)MOFs have rarely been studied,as they are less exposed to the surfaces.Here,for the first time,we synthesized and observed that the 2D layers could align perpendicular to the surface of a 2D zeolitic imidazolate framework L(ZIF-L)with a leaf-like morphology.Owing to this unique orientation,the active sites on the edges of the 2D crystal structure could mostly be exposed to the surfaces.Interestingly,when another layer of ZIF-L-Co was grown heteroepitaxially onto ZIF-L-Zn(ZIF-L-Zn@ZIF-L-Co),the two layers shared a common b axis but rotated by 90°in the ac plane.This demonstrated that we could control exposed facets of the 2D MOFs.The ZIF-L-Co with more exposed edge active sites exhibited high electrocatalytic activity for oxygen reduction reaction.This work provides a new concept of designing unique oriented layers in 2D MOFs to expose more edge-active sites for efficient electrocatalysis.
