Preparation And Properties Of MOF-Based Oxide Gas Sensitive Electrode

Nitrogen oxide sensors have been the focus of researchers who are committed to synthesizing sensitive materials with excellent performance to construct highly sensitive sensors.The metail oxides based on MOFs has the advantages of uniform particles and good dispersion.In this study,the metal oxides of CuO,Co₃V₂O₈ and Au-Co₃V₂O₈ were prepared by Cu-MOF and Co-V-MOF as precursor,and assembled to NO₂ sensors.The composition and microstructure of the sensor were characterized by XRD,XPS and SEM.The gas sensing properties and response mechanism of the sensor were studied by electrochemical impedance spectroscopy and potentiostatic testing.The specific research contents were as follows:CuO was prepared by calcined Cu-MOF at 550℃,and it was assembled to an impedance spectrum type NO₂ sensor.The sensor was tested for sensitivity in the range of650-800℃ with the phase angle as the sensing signal.The results showed that the response value of the sensor had a good linear relationship with the logarithm of 50-700 ppm NO₂.The sensor possessed the highest sensitivity of 8.163 at the frequency of 10 Hz at 700℃.In addition,the sensor showed good stability and immunity to CH₄,CO₂,NH₃ and O₂.Co₃V₂O₈ sensitive material was obtained by calcined Co-V-MOF at 500℃.A mixed-position NO₂ sensor with Co₃V₂O₈ as the sensitive electrode and LSAO as the double-layer solid electrolyte was prepared by screen printing technology.Sensing performance tests showed that the sensor response potential value had a good linear relationship with the logarithm of NO₂ concentration in the range of 550-650℃.At 575℃,the sensor had the highest sensitivity of 78.2 mV/decade.In addition,the sensor with MOF based Co₃V₂O₈ had higher sensitivity and selectivity than those of Co₃V₂O₈ obtained by traditional high temperature solid phase method.Co-V-MOF was further modified by impregnation method to prepare Au-Co₃V₂O₈.The results showed that the modification of Au could significantly improve the sensing performance of the sensor.The detection range is expanded from 10-50 ppm to 5-700 ppm.