The Enhancement Mechanism And Electrochemical Sensing Applications Of M-BTC (M=Ni,Co,Zn) Frameworks

Metal-organic frameworks（MOFs）,a kind of hotspot materials,have been widely used in many fields,such as adsorption separation,catalysis and biomedicine.However,the study of the application in the field of electrochemical sensing is actively exploring,and the influence of the choose of different metal centers on their morphology and electrochemical performance is still lack of systematic studies.Based on this,a series of isostructural M-BTC（M=Ni,Co,and Zn）frameworks were synthesized using H₃BTC as the organic ligand,and the effects of the metal centers on their morphology and electrochemical performance were further studied and discussed.The content is as follows:（1）Using H₃BTC as organic ligand,changing the source of the central metals M（NO₃）₂·6H₂O（M=Ni,Co,and Zn）,three M-BTC（M=Ni,Co,and Zn）frameworks were prepared via the mixing method at room temperature.Under the help of the characterization of X-ray diffraction（XRD）,Fourier transform infrared（FT-IR）,scanning electron microscopy（SEM）,cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）,the formation of isostructural MOFs was confirmed,and the effect of different metal centers on their morphology and electrochemical performance were studied.Choosing ponceau 4R as the object,the electrochemical activity of the three M-BTCs was further studied.It was found that they showed different signal enhancement effects for the oxidation of ponceau 4R.The enhancement mechanism was explored by Chronocoulometry,the three M-BTCs showed different adsorption capacities for ponceau 4R,resulting in differences in the oxidation signal.Then,Ni-BTC owned the most significant signal-enhancement was selected as the sensing materials to construct a novel method for the electrochemical detection of ponceau 4R,with a linear range of 0.5-150 nM,detection limit of 0.08 nM.Finally,this method was used for the detection of ponceau 4R in beverage samples,compared with high-performance liquid chromatography（HPLC）,relative errors less than 6%.（2）The oxidation behavior of adrenaline on Ni-BTC modified carbon paste electrode（Ni-BTC/CPE）was investigated.Compared with bare CPE,the oxidation signal of adrenaline on Ni-BTC/CPE was greatly enhanced.The Chronocoulometry was used to study the mechanism of sensitization.It was found that Ni-BTC significantly improved the accumulation ability of adrenaline on the electrode surface.The mechanism of the oxidation of adrenaline was studied and the results showed that the oxidation involves the transfer of two protons and two electrons.Measurement conditions such as mass content,accumulation potential and accumulation time were optimized for higher sensitivity.Based on the significant signal amplification effect of Ni-BTC,a sensitive adrenaline-electrochemical sensing platform was constructed,with a linear range of 7.0-2000 nM,a detection limit of 0.64 nM.Finally,it was used for the determination of adrenaline in adrenaline hydrochloride injection sample with satisfactory results.