Effect of Fe2+/Fe3+ ratio on photocatalytic activities of Zn1-xFexO nanoparticles fabricated by the auto combustion method

Zn1-xFexO nanoparticles with Fe doping content from 0 % to 6 % were fabricated by a facile auto combustion method. SEM, XRD, PL and XPS were carried out to characterize the morphologies, structures, optical properties and surface chemical states of the samples. The photocatalytic properties were also investigated toward Methyl Orange (MO) degradation. It was found that the maximum photocatalytic activity was obtained by 4 % Fe-doped ZnO nanoparticles, which was ascribed to the highest ratio of Fe2+/Fe3+. The experimental results and DFT calculations indicated that Fe could effectively affect the photocatalytic activity of ZnO nanoparticles, dependent on Fe2+/Fe3+ ratio and doping contents. Furthermore, a conceivable mechanism of band gap structure and carrier transfer of Fe2+/Fe3+ co-existed Zn1-xFexO was proposed according to experimental analyses and theory calculations.