Hollow Cobalt/nc Catalyst Derived From Zinc/cobalt Bimetallic Organic Framework For Catalytic Applications

Due to the porosity,large specific surface area,and variability of metal nodes and organic ligands,metal-organic frameworks(MOFs)are ideal precursors for the preparation of porous carbon-supported catalysts.Among them,metal/NC catalysts derived from zeolitic imidazolate framework(ZIF)materials have received extensive attention.However,currently,most of the metal/NC catalysts are derived from solid ZIFs,which have limited exposed active sites and large diffusion resistance,resulting in the catalytic efficiency.To solve this problem,we aim to design and synthesize the hollow metal/NC catalysts to improveits catalytic performance.The main research contents are as follows:1.Providing a synthesis method of single-atom site Co/NC catalysts with hollow structure derived from Zn/Co bimetal-organic framework(BZIF).We obtained the hollow Zn/Co bimetallic ZIF by tannic acid etching method with Zn/Co bimetallic ZIF as precursor.Then we pyrolyzed the hollow Zn/Co bimetallic ZIF and successfully prepared the hollow structure single-atom site Co/NC catalysts.This method is applied to synthesize other kinds of single-atom site metal/NC catalysts with hollow structure(such as Cu/NC,Mn/NC,etc.).Using the oxidative coupling reaction of anilines as a probe reaction,we investigated the catalytic performance of the single-atom site Co/NC with hollow structure.The single-atom site Co/NC catalysts with hollow structure have a higher conversion than the corresponding solid bulk structure.At the same time,after several cycles,its conversion and selectivity did not decrease significantly,which proved its good stability.2.Developing a method for synthesis and morphology control of hollow Co/NC catalysts.Through the regulation of reaction parameters,the morphology of Zn/Co BZIF was controlled,and a series of different morphologies of Zn/Co BZIF,such as spines ball,flower-like and truncated rhombohedral dodecahedron,were obtained.And explore the influencing factors of morphology.Hollow Co/NC catalysts with different morphologies such as spines ball,flower-like and truncated rhombohedral dodecahedrons were successfully prepared by etching and pyrolysis.Compared with ordinary hollow Co/NC,the "spines ball" hollow Co/NC catalyst exposed more active sites and increased the contact area with the substrate,thus effectively promoting its ORR catalytic activity.