Research On The Photoelectrocatalytic Activity Of The CoZnAl Hydrotalcite Modified Electrodes

The layered double hydroxide?LDH?is also called anionic-clay or hydrotalcite-like compounds,which is a kind of anion-type layered material.Its body sheet possesses positive metal ions,and negative anions locate between layers.The cations and anions combined with each other via chemical bond?covalent bond?.The LDH has special properties,such as the composition of metal cations on layer sheet can be adjusted,the interlayer anion can be exchanged,the layer structure can be reconstructed,a appropriate porous structure,a simple synthesis process,environmental friendly property,and so on.Thus,hydrotalcite has a bright application prospect in environmental protection,catalytic reaction,photoelectrochemical,pharmaceutical preparation and other fields.The layered structure of LDHs has synergistic effect on charge transfer which can effectively prevent the recombination of electron-hole pairs and avoid the agglomeration of the nanoparticles.As the electrode material,when the layered double hydroxide was modified on the surface of the electrode,it can promote the electron transfer in the electrochemical reactions,resulting in its broad application prospection in the field of photoelectric chemistry.In this paper,Co Zn Al LDHs with different amounts of cobalt were prepared by coprecipitation method using Co?NO₃?₂,Zn?NO₃?₂,Al?NO₃?₃ as raw materials.The resulted samples were characterized by XRD and UV-Vis to confirm the crystal structures and the absorption properties under visible light.The Co Zn Al LDH modified electrodes were prepared by the coating method and the photo-generated current and electrochemical performances of the film electrodes were tested by three electrode system.The effects of the catalytic process,pH,type of electrolyte solution,concentration of electrolyte solution,orange were tested.The results showed that the single hydrotalcite phase was obtained in different amount of doped Co.The Co Zn Al-LDHs had absorption ability in the ultraviolet and visible light zone,and the Co Zn Al-LDHs modified film electrodes had excellent electrochemical performance and ability of photoelectric corresponding.It was found that the most photo-generated current was generated on the Co Zn Al-LDHs with the ratio Co:Zn:Al=0.2:2:1modified film electrodes.When the Co Zn Al-LDHs modified film electrodes were used as work electrode,the decolorization percentage of methyl orange reached90%after irradiation under visible light for 240 min at the following conditions:the concentration of methyl orange solution was 5 mg/L,1 mol/L of Na NO₃ was used as electrolyte,and solution pH was 5.