Characterization of undoped and Co doped ZnO nanoparticles synthesized by DC thermal plasma method

ZnO nanopowders doped with 5 and 10 at% cobalt were synthesized and their antibacterial activity was studied. Cobalt doped ZnO powders were prepared using dc thermal plasma method. Crystal structure and grain size of the particles were characterized by X-ray diffractometry and optical properties were studied using UV–vis spectroscopy. The particle size and morphology was observed by SEM and HRTEM, revealing rod like morphology. The antibacterial activity of undoped ZnO and cobalt doped ZnO nanoparticles against a Gram-negative bacterium Escherichia coli and a Gram-positive bacterium Bacillus atrophaeus was investigated. Undoped ZnO and cobalt doped ZnO exhibited antibacterial activity against both E. coli and Staphylococcus aureus but it was considerably more effective in the cobalt doped ZnO.

Research highlights
► In this study we have used a novel dc thermal plasma method for the synthesis of Co doped ZnO.
► In this present work we have used air as a reacting gas.
► The influence of Co dopant on the antibacterial activity of ZnO nanoparticles.