The influence of oxygen concentration on the formation of CuO and Cu2O crystalline phases during the synthesis in the plasma of low pressure arc discharge

•We are studied the features of the formation of crystalline phase in copper oxide nanoparticles.•We used the method of condensation from the vapor deposition for the synthesis of Cu2O.•We are studied the photocatalytic activity of the produced Cu2O nanoparticles.

This paper describes the synthesis of copper oxide nanoparticles with different percentages of CuO and Cu2O phases. It was achieved by the control of the percentage of oxygen in the gas mixture (N2 + O2) in a plasma-chemical process of evaporation-condensation by means of low-pressure arc discharge. In all the experiments, the pressure in the plasma-chemical reactor remained constant at 60 Pa. By means of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) it was found that the average particle size was 6 nm, and Cu2O phase content decreases with increasing oxygen content in the gas mixture. High photocatalytic properties of Cu2O powder were shown by the example of the reaction of the methyl orange dye decomposition in water solution. The problems, associated with the performance of this method and the formation of crystalline phases, are discussed.