Preparation And Properties Of Nano-NiO And NiO-CdS Composites

In this dissertation,nickel compounds were used as the main raw materials to prepare three kinds of adsorption materials nickel oxides with different morphologies,good adsorptivity,and recyclable environment-friendly.Different images of nickel oxides were synthesized with cadmium sulfide at different conditions to form NiO-CdS composites by microwave method.The morphologies and properties of the NiO-CdS composites were characterized by FESEM,SEM,TEM,HRTEM and XRD.The growth mechanism and adsorption-photocatalytic properties were further discusse d.(1)NiO and NiO-CdS composites with good dispersity were successfully synthesized by green microwave-assisted chemical synthesis,water bath and subsequent calcination.The synthesized products were characterized by XRD,FESEM,SEM and TEM.And it is used for adsorption-photocatalytic degradation of dye CR.The experimental results show that the maximum adsorption performance of rod-shaped NiO for CR is 99.95 mg g-1 according to the Langmuir isotherm equation,and the degradation rate of CR(50 mg/L)is 98.28%for NiO-CdS composite.NiO and NiO-CdS complexes have good adsorption-photocatalytic activity for dyes with CR.(2)Single crystal two-dimensional(2D)porous nano-NiO sheets with diameters of 100-210 nm and thickness of 10-20 nm were prepared by low-cost water bath and calcining method.Porous nano-NiO and CdS were synthesized under microwave conditions to obtain NiO-CdS complexes with the same morphology.The synthesized products were characterized by XRD,FESEM,TEM,HRTEM,SAED and N2 adsorption/desorption isotherms.The formation mechanism of single crystal porous nano-NiO and NiO-CdS composites is briefly discussed.As an adsorbent,the prepared single-crystal porous NiO showed excellent performance in removing Congo red(CR)from water rapidly.The results show that the adsorption isotherm conforms to the Langmuir adsorption model and the calculated maximum adsorption capacity is 193.2 mg-g-1 which is higher than that of other reported 2D NiO structures.The removal rate of CR(80mg/L)is 98.12%by NiO-CdS complex.Only 37.9%and 26.9%of CR molecules were removed on NiO and CdS,The results clearly show that the NiO-CdS nanocomposite has the highest photocatalytic capability among the three samples.(3)The flower spherical NiO and NiO-CdS composites were prepared by simple,mild water bath method and microwave method without organic templating agent.The crystal structure,composition and morphology were characterized by XRD,FESEM and TEM.The pore structure was clearly observed by FESEM and TEM,and it was clearly observed in the FESEM image that the CdS particles were uniformly dispersed on the surface of NiO.The spheroidal NiO exhibited excellent adsorption capacity for CR,and the maximum adsorption capacity was 490.15 mg·g-1.After four cycles of use,NiO still maintained a high removal rate,indicating that it can be used as an effcient and recyclable adsorbent for removing organic dyes from water.In the photocatalytic degradation of CR(90mg/L)solution,the degradation rates of NiO and CdS were only 64%and 31%,respectively,while the degradation rate of the composite was the highest,reaching 98.01%.It shows superior performance over a single substance,which leads it to a preferred material for photocatalytic degradation of dye CR.