Microwave Irradiation Synthesis Of Nanostructured Ni（OH）₂,CuO/CNTs And Their Performance Study

Dye wastewater caused environmental problems and energy crisis all together threat thesustainable development of human beings. Typically, nanostructured materials, especially3D hierarchical architectures, offer potential advantages in dye removal applications andenergy storage due to their large surface-exposure area and a large fraction of atomsavailable for physical adsorption or chemical reaction. Because Ni（OH）₂has layeredstructures, they tend to be thin flakes or platelets in natural/normal formation environments,we choose it as the adsorbent and/or photocatalysis for the dye wastewater treatment.Because of low cost, abundant resources, non-toxicity, Stability of the electrochemicalproperties, CuO can be the electrode materials for the supercapacitor. We combine the CuOand CNTs together, due to the synergistic effect, the composite structure shows the bestelectrochemical performance. The main contents and conclusions are summarized asfollows:（1） Through changing the reaction temperature and the amount of urea,3D flowerlikeNi（OH）₂architectures including α-and β-Ni（OH）₂phases, respectively, have beensuccessfully synthesized via a facile microwave-assisted hydrothermal method.（2） α-Ni（OH）₂has highly selective adsorption of anionic dye due to its surface positivecharged and has good photocatalytic activity. Flowerlike β-Ni（OH）₂nanostructuressynthesized from microwave-assisted process with positively charged and hydrophobicsurface can adsorb both cationic dyes and anionic dyes from aqueous solutions. Studiesfound that the electrostatic interaction plays a dominate role in the adsorption of the anionicdyes, whereas the cationic dyes was bound through the hydrophobic interaction. In addition,（3） Adsorption Kinetic and Equilibrium for the β-Ni（OH）₂nanostructures adsorption ofanionic dye （AF） and cationic dye （MB） were evaluated, indicating that the sorption systemsfollowed the pseudo-second-order model with the correlation coefficients higher than0.998and the equilibrium data were best described by the Freundlich isotherm model.（4） CuO-CNTs composite structure with spindle-shaped morphology has been synthesizedthrough a simple hydrothermal method. Comparing the CV, charge-discharge, and cyclingperformance with CuO, pure CNTs, the CuO-CNTs composite structure has higher specificcapacitance and excellent cycling stability.