Fabrication Of Modified Carbon Paper Electrodes Based On Mn-MIL-100 Materials For Enhancing Phenolic Compounds Degradation

For the problem of low electrochemical degradation rate for phenolic pollutants,it had been carried out that modifying carbon paper electrodes based on metal organic framework（MOFs）materials to improve the electrochemical efficiency and the degradation rate of organic pollutants in this paper.The Mn-MIL-100 material was prepared by hydrothermal method and mixed with carbon black（C）according to a certain proportion.Carbon paper（CP）electrode was modified with the mixture and the Nafion adhesive.The successful loading of Mn-MOF/C onto CP surface was proved by scanning electron microscopy（SEM）and the X-ray diffraction（XRD）.By means of cyclic voltammetry（CV）,impedance spectroscopy（EIS）,chronopotentiometry（CA）,etc,it was found that the electrochemical activity and stability of the Mn-MOF/C modified CP electrode were significantly improved,compared to the Mn-MOF modified CP electrode and bare CP electrode,due to the synergistic effect between Mn-MIL-100 and C where the doping of C enhanced the conductivity and stability of the system.The application of Mn-MOF/C modified CP electrode as cathode showed that its excellent reduction degradation efficiency on 4-nitrophenol and formation rate of p-Aminophenol were as high as94%and 66%respectively at p H=2.The effects of metal ions in MIL-100 series on the electrochemical degradation efficiency to 4-nitrophenol were preliminarily investigated with the method of CV,showing that the unique mixed valence metal cluster of Mn³⁺/Mn²⁺in the topological structure of Mn-MIL-100 could provide more catalytic active sites for facilitating the electrochemical reduction of PNP.Under different pyrolytic temperature of 300°C/400°C/500°C,Mn-MIL-100-derived carbon-based materials was obtained.Fabrication of Mn-MIL-100-derived carbon-based materials onto the surface of CP electrodes with the Nafion adhesive were characterized by SEM and the X-ray diffraction XRD.Compared with the low current response of Mn-MOF modified CP and Mn300 modified CP electrode（Mn300@CP）in CV test,Mn400 modified CP（Mn400@CP）and Mn500 modified CP（Mn500@CP）possessed the higher specific capacitance and significant electrocatalytic activity towards phenol,due to increased proportion of Mn³⁺and growed oxygen vacancy with the increasing pyrolytic temperature.Mn400@CP and Mn500@CP had better electrochemical stability due to the completed carbonization process of the organic ligand which improved the conductivity and stability of system.For the obvious agglomeration phenomenon of Mn500 reducing the effective active area,the values of transfer resistance(R_ct)and diffusion resistance for Mn400@CP ware lower than that of Mn500@CP,indicating the better electrochemical performance of Mn400@CP.The application of Mn400@CP electrode as anode showed that its excellent oxidation degradation efficiency on phenol reached 96%at p H=4.