Preparation of a ZIF-67 Derived Thin Film Electrode via Electrophoretic Deposition for Efficient Electrocatalytic Oxidation of Vanillin.

The electrophoretic deposition method is employed to deposit uniform metal organic framework thin films. ZIF-67 particles dispersed in isopropanol move to a cathode as an electric field is applied on two conducting glass electrodes, the uniform ZIF-67 thin film can be formed on the conducting glass substrate. As the deposition time is fixed at 1 min, the prepared film thickness can be adjusted from 1.0 to 7.0 μm by applying different electric fields from 20 to 60 V·cm-1. The deposited ZIF-67 thin film is further converted into porous Co9S8 thin films by the vulcanization with S powder. The porous thin films vulcanized at different temperatures are characterized by the measurements of scanning electron microscope, X-ray photoelectron spectroscopy, X-ray powder diffraction, high resolution transmission electron microscopy, and Fourier transform infrared spectra. The prepared porous Co9S8 thin films are used as the thin film electrode to catalyze the degradation of vanillin. The Co9S8 thin film vulcanized at 500 °C shows better catalytic performance than the bare glassy carbon electrode and the electrodes vulcanized at other temperatures. The electrocatalytic degradation enhancement mechanism is analyzed by the measurements of Tafel curves and electrochemical impedance spectroscopies. It can be developed as a feasible method for the electrocatalytic detection of vanillin.