PHOTOLUMINESCENCE AND PHOTOCATALYTIC ACTIVITY OF Mn-DOPED ZnO NANOPARTICLES

Nanocrystalline ZnO particles doped with Mn(II) ions were prepared by a forced hydrolysis method of zinc acetate dihydrate and manganese acetate tetrahydrate, under reflux, in buthanol. The precipitate obtained was separated by centrifugation at 9.000 rpm and purified by refluxing in water. The dopant percentage was 1, 2.5 and 5%. The qualitative composition of the nanopowder has been evidenced in the elemental EDS maps. Optical investigation shows that the Mn doping in ZnO lattice leads to a decrease in the near band edge position due to the introduction of new unoccupied states by Mn 3d electrons. The luminescence of ZnO is quenched by increasing the dopant ions percentage. At doping rate of 1% Mn in the ZnO lattice a tenfold decrease in intensity of luminescence was observed, along with modification of the luminescence pattern. Further increases of dopant percent from 1% to 5% had as result a decrease of only 30% in the luminescence intensity. The photocatalytic activity was investigated against methylene blue. The increase of Mn percentage leads to a better photocatalytic activity.