Auto combustion synthesis and characterization of Co doped ZnO nanoparticles with boosted photocatalytic performance

Abstract

In this report, pure ZnO and Co doped ZnO (1, 2.5, 5, 7.5 wt% of Co) nanoparticles were synthesized by using one-pot flash combustion synthesis technique. Structural, morphological, optical and photocatalytic properties of the prepared samples were analyzed by using different characterization techniques. The X-ray diffraction results shows the pure ZnO and Co:ZnO samples exhibits hexagonal wurtzite structure having preferential growth along the (101) plane without the presence of secondary phase impurities. The crystalline size of the 7.5% Co:ZnO sample was found to be higher with a value of 27.14 nm with low dislocation density and strain values of 1.36 × 10−3 and 4.38 × 10−3, respectively compared to the other prepared samples. The morphology of the prepared samples were obtained using FESEM analysis which revealed a non-uniform spherical shaped nanoparticles for pure ZnO and the morphology becomes uniform with the incorporation of the Co dopants. The e-mapping and the EDX results confirms the presence of Zn, O and Co elements. UV–Vis. absorption spectrum revealed that the inclusion of Co dopants in ZnO incorporation leads to higher absorption and decrease in band gap. The band gap values of ZnO are noticed to be reduced from 3.27 eV 2.81 eV with Co doping from 0 to 7.5 wt%. Photocatalytic performance of the prepared samples was evaluated in the decolourization reaction of methyl green aqueous solution under the illumination. The prepared Co doped ZnO samples exhibited several times higher photocatalytic activity than bare ZnO. The kinetic model was proposed and the rate constant for the decolourization reactions was calculated. The best performed sample was 5 wt% Co, in which the rate constant was 2.6 times higher than that of bare ZnO.