Tunable atmospheric microplasma synthesis of nitrogen-doped zinc oxide and titanium dioxide nanostructures

Abstract

In this work, a parameter tunable microplasma synthesis method operating under atmospheric conditions is presented. By adjustment of the liquid electrode composition and/or applied power to the microplasma, either titanium dioxide nanostructures (nanoparticles and nanowires) or nitrogen-doped zinc oxide hexagonal sheets with nanometer thicknesses can be formed after annealing at 400 °C. Morphological and composition control of the nanostructures occurs through adjustments of the liquid electrode composition, pH and the applied power of the microplasma during the synthesis. XRD patterns confirmed the presence of the wurtzite phase in the nitrogen-doped zinc oxide samples, but also show a difference in the peak ratios and peak broadening when compared to zinc oxide standards. XPS analysis indicates the presence of nitrogen in the wurtzite zinc oxide structure as both α-N and β-N, indicating nitrogen doping through substitution and interstitial chemical doping mechanisms. The binding energy for the Zn 3d peak shows a common shift to 10.8 eV that is indicative of nitrogen doping of zinc oxide structures. Atmospheric microplasmas with liquid electrodes provide the opportunity for the creation of complex structures consisting of nitrogen-doped zinc oxide.