Abstract:

The layered cobalt-iron layered bimetallic hydroxide （CoFe-LDH） was prepared by hydrothermal method with cobalt and iron as the active sites. The optimized powder catalyst is obtained with the element ratio n（Co）∶n（Fe）=3∶1 at 120 ℃ 18 h， and the hydrothermal time significantly affects the catalytic performance. Insufficient hydrothermal time， temperature or urea dosage is unconducive to crystal growth. However， excessive increase of reaction conditions will change the crystal shape and make the lamella thicker. Furthermore， the optimized CoFe-LDH is loaded on the copper foam （CuF） surface， obtaining the recyclable terpolymer CoFe-LDH/CuF （CFHC） sheet catalyst. Due to reduced Cu elements' participation， the molar percentage of oxygen vacancy on the catalyst surface is increased by 45.90%. The catalysis performance of CFHC is evaluated by characterizing the diuron （DUR） elimination efficiency， a harmful phenyl urea group herbicide， in the DBDP system， and the DUR degradation rate in the DBDP/CFHC system is 3.18 times as high as that in the DBDP system. The structure and composition of CFHC are characterized systematically， and the intrinsic relationship between the microstructure， elemental composition， and catalytic performance is studied. The introduction of CuF increases the conductivity of the catalyst and the reducible copper increases the oxygen vacancy molar percentage content. Thus， the fundamental reason for the high catalytic activity is the electron transfer in cobalt， iron， copper， and oxygen vacancy in the degradation process. CFHC re-adjusts the dominant active species in the DBDP system. ·{\mathrm{O}}_{\mathrm{2}}^{-} and ¹O₂ replaced ·OH as the main active substances for the degradation of DUR. The work would positively affect the DBDP catalysis development， the functional structure design， and the selection of active species.

Key words: Layered bimetallic hydroxide, Dielectric barrier discharge plasma, Iron and cobalt, Diuron, Copper foam