Paper Title
EFFECT OF CA DOPING ON THE CATALYTIC ACTIVITY OF CuO NANOPLATELETS SYNTHESIZED VIA HYDROTHERMAL ROUTE

Abstract
Abstract - Crystal structure, morphology and chemical composition are the main parameters responsible on material properties. For nanomaterials the properties due to the size and surface effects become predominant. Also materials properties can be modified by the incorporation of doping elements in the initial structure.The aim of this work is to highlight the effect of Ca-doping on the structuralproperties of CuO nanoparticles (NPs) and to evaluate their catalytic activity on the degradation of the widely used organic pollutant methylene blue (MB) dye.To carry out our study, catalyst samples of CuO and Ca-doped CuO NPs were synthesized with different concentrations (0, 2, 4, 6 and 8 wt%) of Ca. The catalyst particles were synthesizedusing hydrothermal method, which has the ability to produce NPs of different sizes and morphologiesthatare often involved in the catalytic activity of materials.This featureis an alternative pathway to remove contaminants from water.In the synthesis procedure, reagents CuSO4.5H2O and NaOH were dissolved in distilled water under stirring and CaCl2.6H2O was added for doping. After the hydrothermal treatment the obtained precipitates were separated by centrifugation, washed with distilled water and ethanol and finally dried in an oven.The characterization by XRD demonstrated that particles without Ca doping have the monoclinic structure of CuOwith space group C2/c andthe crystallite sizes were found of nanometric scale. For Ca-doped CuO particles, supplementary XRD peakswere observed and were attributed to the effect of Ca. For the high Caconcentrations, the intensity of the new peaks increases indicating the formation of a new phase that was identified as CaSO4x0.66H2O which has a monoclinic structure with the space groupI2.The limited solubility of Ca into CuO lattice is probably due to the large difference between the cation sizesof Cu2+(72 pm) and Ca2+(99 pm).This fact has led to the formation of particles of Cu/CaSO4x0.66H2O nanocomposite.The FT-IR spectra have confirmed the formation of both CuO and CaSO4oxides.The SEM micrographs show pureCuONPs with regular rectangularplatelet-like morphology, while theCu/CaSO4x0.66H2O nanocompositeshave a degraded rectangular form. The specific surface area of particles from BET measurement is in the range 9-15 m2/g.The efficiency of catalytic activity of the synthesized samples was checked on the degradation of the MB dye. The results demonstrated a large catalytic activity due to the platelet-like morphology, the important specific surface area and the use of H2O2hydrogen peroxide solution. The degradation rate has reached 93%and 100% of the initial concentration,in a relatively short time of 20 min, for pure CuOand CaSO4x0.66H2O NPsrespectively. Keywords - Hydrothermal synthesis, catalytic activity, CuO and CuO/CaSO4x0.66H2Onanoparticles.