Dual doping effect of Ag+ & Al3+ on the structural, optical, photocatalytic properties of ZnO nanoparticles

ZnO nanoparticles with the size ∼ 20 nm to 40 nm were prepared by dual doping of Ag+ and Al3+ ions using a microwave-assisted chemical synthesis technique. The composition of Ag is fixed as 2 at.% and Al is varied from 0 to 6 at.%. The prepared ZnO nanoparticles were characterized using XRD, HRTEM, FESEM, EDS, XPS, FT-IR, Raman spectra, UV- visible spectra and photocatalytic studies. XRD results confirmed the crystallinity and hexagonal wurtzite structure of Ag+ and Al3+-doped ZnO nanoparticles. It is observed that the increase of the Al dopant ratio reduced the crystallite size. EDS and FT-IR data supported the purity of samples. The optical band gap values showed a blue shift (3.54 eV to 3.89 eV) as the Al doping ratio increased. The blue shift is discussed in terms of the doping process and induced some transitions on inter bands. The photocatalytic activity of synthesized samples was monitored using Methylene Blue dye. The low absorbance and high degradation efficiency were obtained for the high-doping concentration of Al on all irradiation times. The leaching study shows no catalyst leaching into the reaction medium