Characterizations and photocatalytic activity of zinc oxide nanoparticles by arc discharge

Abstract

ZnO nanoparticles were successfully synthesized by arc discharge using two difference electrodes, i.e., a zinc anode and a graphite cathode, which were submerged in de-ionized water. Gas mixture of oxygen and nitrogen was continuously supplied through holes in the cathode, while the arc was initiated by applying electrical current between the electrodes. Consequently, zinc anode was vaporized and reacted with oxygen to form ZnO nanoparticles. The effects of synthesis parameters, which are anode speed, arc current, water temperature and oxygen concentration in the gas mixtures on characteristics of ZnO nanoparticles were investigated and reported. Electron microscopy showed that the products are semispherical and ellipsoid particles with the average size of 20-50 nm. Optical characterizations indicated blue photoluminescence emission which corresponds to Zn interstitial defects of ZnO and leads to reduction in the band gap of the products. The photocatalytic activity of the as-prepared ZnO nanoparticles was evaluated via methylene blue (MB) degradation. The results showed that not only the particle size and surface area affects photocatalytic activity of the synthesized ZnO but also the intrinsic defect on the surface.