Chiral Metal Organic Hybrid Materials And Electrocatalytic Properties

In the past few decades,metal-organic frameworks（MOFs）have gradually become attractive materials in various fields.Compared with other traditional catalysts,MOFs have advantages of higher specific surface area,adjustable porosity,controllable structure,open metal sites and easy modification of functional groups.By interacting with MOFs（especially non-noble metal MOFs）ligands,functional micromolecules and nanomaterials can diffuse into the pores of MOFs,or be derived by covalent bonds and coordination bonds during mineralization of MOFs.It is hybrid materials of MOFs,which has a wide range of applications in the fields of catalysis,energy storage,adsorption and separation.However,related research on chiral metal-organic hybrid materials（CMOHMs）is relatively poor.This article is devoted to the construction of CMOHMs and the research of electrocatalytic performance.The research content is mainly divided into the following three parts:1.Chiral carbon quantum dots（CCQDs）doped with nitrogen-rich MOF nanosheet array catalyst was used for electrochemical recognition of tyrosine（Tyr）isomers.The CCQD were synthesized by microwave pyrolysis using D-sorbitol,and a simple one-step electrodeposition method was first developed to introduce CCQD into Cu-TDPAT on nickel foil（MOF@CCQD/Ni F）.Achiral Cu-TDPAT was used as the supporting framework of CCQD to construct acceptor units,where CCQD not only acts as a chiral selector,but also promotes the transfer of electrons.Characterizations such as solid-state circular dichroism specta（CD）,ultraviolet visible spectroscopy（UV-vis）and fluorescence emission spectroscopy proved that CCQDs were successfully dispersed in the voids of MOF.This kind of integrated electrode with uniform and dense membrane not only shows high selectivity,sensitivity and quantitative analysis for Tyr,but also has the ability to measure L-Tyr%enantiomer mixture.This shows that the chiral sensor can be used for qualitative and quantitative analysis of Tyr’s actual related recognition field.2.β-Cyclodextrin（β-CD）functionalized chiral MOF composite material recognizes both tryptophan and penicillamine enantiomers.In order to improve the ability and work efficiency of electrochemical chiral recognition,a sensorβ-CD/Ca-sacc/GCE with multiple chiral sites（chiral cavity forβ-CD and chiral skeleton for Ca-sacc）was constructed.This sensor combined the advantage ofβ-CD and Ca-sacc to identify Trp and Pen enantiomers simultaneously for the first time.By optimizing the experimental conditions of electrically oxidizing time withβ-CD on Ca-sacc/GCE,electrolyte PH and reaction temperature,the experiment results show a successful recognition of Trp and Pen enantiomers within the narrow electrochemical window and wide linear range,low detection limits（DLs）,high reproducibility and stability atβ-CD/Ca-sacc/GCE.The strategy for integration is crucial to promote electrochemical enantioselective recognition of chiral compounds。3.Highly efficient urea-anodizing promotes the electrochemical nitrogen reduction process.Herein,we developed a functionally integrated strategy that replaces water with much readily oxidized urea to promote the electrochemical N₂ fixation.With high BET surfaces and rich 3D-interconnected porous structures,MOFs are superb self-sacrificing templates toward the fabrication of durable carbon and doping with heteroatom-based noble-free catalysts,serve as both cathode and anode for N₂ reduction and urea oxidation.In this text,Cu O,Cu₂O nanoparticles,and carbon dots（CDs）embedded in a C,N-codopednanoarray supported on nickel foam（Ni F）derived from Cu-MOF@CDs/Ni F was synthesized,which is marked as Cu O/Cu₂O@CDs-CN/Ni F.The present Cu-MOF used nitrogen-rich{2,4,6-tris（3,5-dicarboxylphenylamino）1,3,5-triazine}as organic linkers and Cu（II）as metal nodes.The oxidation-pyrolysis of Cu-MOF leads to the in situ generation of Cu O and Cu₂O nanoparticles anchored on a periodically-ordered C,N-codoped nanoarray.It is significant that an NH₃ yield of 102.2μg h^-1 cm^-2 and faradaic efficiency（FE）of 23.91%at 0.40 V were obtained in 1.0 M Na₂SO₄ with 0.5 M urea,which is 33.82μg h^-1 cm^-2and 8.02%more than those of the urea-free counterpart with long-term electrochemical durability.