Optical and Structural Properties of ZnO Nanoparticles Synthesized by CO2 Microwave Plasma at Atmospheric Pressure

The results of carbon-doped zinc oxide nanoparticles synthesized by CO2 microwave plasma at atmospheric pressure are presented. The 2.45-GHz microwave plasma torch and feeder for injecting Zn granules are used in the synthesis of zinc oxide nanoparticles. The Zn granules (13.5 g/min) were introduced into the microwave plasma by CO2 (5 l/min) swirl gas. The microwave power delivered to the CO2 microwave plasma was 1 kW. The synthesis of carbon-doped zinc oxide nanoparticles was carried out in accordance with CO2 + Zn → carbon-doped ZnO + CO. The synthesized carbon-doped zinc oxide nanoparticles have a high purity hexagonal phase. The absorption edge of carbon-doped zinc oxide nanoparticles exhibited a red shift from a high-energy wavelength to lower in the UV-visible spectrum, due to band gap narrowing. A UV-NIR spectrometer, X-ray diffraction, emission scanning electron-microscopy, energy dispersive X-ray microanalysis, Fourier transform infrared spectroscopy, and a UV-Vis-NIR spectrophotometer were used for the characterization of the as-produced products.