The Fabrication And Application Of Modified Electrode Based On HKUST-1 And Its Composite

In recent years,the copper-based metal-organic framework(HKUST-1)and its composite have the advantages of large surface area,excellent heat endurance and outstanding chemical stability,which make them have a good performance on electrochemical sensing application.The copper-based metal-organic framework has a larger void volume and is easy to composite with other materials.On this purpose three modified electrodes were fabricated and their electrochemical characters were studied.The HKUST-1 modified glassy carbon electrode(GCE)as a highly sensitive and selective electrochemical sensor(HKUST-1/GCE)for the determination of dopamine(DA)has been developed.The HKUST-1 was prepared by hydrothermal,and the morphology and crystal phase of the MOFs were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD),respectively.Meanwhile,the electrochemical performances were investigated using the cyclic voltammetry(CV),differential pulse voltammetry(DPV)and electrochemical impedance spectroscopy(EIS).Compared with the bare GCE,the HKUST-1 modified electrode showed a strong enrichment to DA,which made the HKUST-1 exhibit excellent electrochemical performance in the detection of DA.The linear response range was from 5.0 × 10-7 to 1.0 × 10-4 M and the detection limit was as low as 1.5 × 10-7 M.Moreover,the HKUST-1/GCE had preeminent electrocatalytic activity and high selectivity toward DA in the presence of ascorbic acid(AA)with a satisfactory result.An electrochemical sensor was presented for the simultaneous determination of hydroquinone(HQ)and catechol(CT)based on HKUST-1-graphene composites modified glassy carbon electrode(HKUST-1-GN/GCE).The modification procedure was carried out through casting HKUST-1 and graphene oxide(GO)composites(HKUST-1-GO)on the bare GCE and followed by the transformation of HKUST-1-GO to HKUST-1-GN by an electrochemical reduction.The electrochemical behaviors of hydroquinone(HQ)and catechol(CT)at HKUST-1-GN/GCE were investigated by CV,DPV and EIS.The HKUST-1-GN/GCE had outstanding electroanalytical performance and high selectivity toward HQ and CT.The electrochemical sensor exhibited a linear response in the same range of 1.0 × 10-6 to 1.0 × 10-3 M with the detection limits of 5.9 × 10-7 M for HQ and 3.3 × 10-7 M for CT(S/N = 3).Four samples of tap water spiked with different concentrations of HQ and CT were considered.The method has been applied to the analysis of these isomers in spiked tap water with recoveries from 99.0-102.9 % and relative standard deviations(RSDs)for 5 successive measurements less than 5 % were also acceptable.Moreover,this sensor was applied to detect HQ and CT in the real samples with satisfying results.The HKUST-1–gold composites(Au-HKUST-1)are successfully synthesized through a coordination replication strategy at room temperature.In this work,we applied Au-HKUST-1 composites for non-enzymatic glucose sensing in alkaline media.The structure and properties of the as-prepared Au,HKUST-1 and Au-HKUST-1 were characterized by a set of techniques,including transmission electron microscope(TEM)and XRD.Meanwhile,the electrochemical behavior of glucose at Au-HKUST-1/GCE was investigated by CV,EIS and current-time response curves.At the optimal detection potential of 0.60 V,the glucose electrochemical sensor exhibited two linear ranges of 0.5-20 ?M(R2 = 0.9991)and 20-1400 ?M(R2 = 0.9995)with a detection limit of 0.1 ?M(S/N = 3).The current-time of response reached 95 % of steady-state current within 5 seconds.The interference study was made using coexisting substances including DA,UA,AA and KCl with outstanding selectivity and rapid detection for glucose.