Synthesis And Photocatalytic Properties Of Ni Co-LDH Semiconductor Composite Materials

In recent years,various layered bimetallic hydroxides have been synthesized by technology workers using methods such as co-precipitation,hydrothermal synthesis,template synthesis,and calcination reduction.Among them,layered bimetallic hydroxides stand out in the field of semiconductor photocatalysis due to their advantages of simple preparation,controllable morphology,and eco-friendliness.However,their limited active interface and low charge separation efficiency have always hindered the improvement of their photocatalytic performance.Therefore,inhibiting their photo-generated charge separation efficiency and enhancing their active surface sites are currently the key problems that need to be addressed.In this study,to increase the interlayer spacing between layered bimetallic hydroxides and expand their active sites,an improved hydrothermal method was adopted to replace the solvent with anhydrous ethanol and control the cation ratio(1:1)to prepare flower-like nickel-cobalt layered bimetallic hydroxides(Ni Co-LDH)with larger interlayer spacing.The photocatalytic performance of the composite material was evaluated by degrading methylene blue dye.Finally,by preparing cadmium sulfide(CdS)nanoparticles and silver chloride(Ag Cl)nanoparticles for compounding,the core-shell structure and convex contact structure were respectively constructed to enhance the photocatalytic performance.The main research plan is as follows:(1)CdS nanoparticles were prepared by co-precipitation,and different ratios of composite material CdS/Ni Co-LDH(CdS/NCL)were prepared under stirring at room temperature using anhydrous ethanol as the solvent.The flower-like Ni Co-LDH with large volume and large layer spacing was used as the core,and the outer layer was coated with a CdS nanoparticle shell with a good band gap width to form a core-shell structure.The optimal composite ratio was found to be 60% CdS/NCL,which achieved a degradation efficiency of 99.1% for 5 mg/L methylene blue pollutant within 60 min,which was 11.4 and 2.7 times higher than that of single Ni CoLDH and CdS,respectively.And through the combination of experiments and theoretical calculations,it was further proved that the separation efficiency of the photogenerated charge of the composite material was improved,and the degradation mechanism of the p-n heterojunction CdS/NCL semiconductor material was analyzed.(2)An improved method was used to grow Ag Cl nanoparticles on the surface of flowerlike Ni Co-LDH using ethylene glycol as the solvent.The Ag Cl nanoparticles with high light absorption ability and fluorescence emission characteristics are uniformly anchored on the surface of large-volume flower-like Ni Co-LDH particles to form active convex contacts to prepare composite materials Ag Cl/Ni Co-LDH(AC/NCL).By degrading 10 mg/L of methylene blue solution with 0.7 g/L AC/NCL,the results showed that the best composite ratio was 35%AC/NCL,and the degradation rate of methylene blue pollutants can reach 98.3% within 12 min.Compared with the degradation efficiency of single Ni Co-LDH and Ag Cl,it was improved by30.54 and 3.67 times,respectively.And according to the combination of experiment and theoretical calculation,it was further proved that the separation efficiency of photogenerated charge of AC/NCL composite material was improved,and the degradation mechanism of n-n heterojunction AC/NCL semiconductor material was analyzed.