Quantitative Relationship Between the Ratio of Fe2+/Fe3+ in Fe3O4 and its Energy Gap in Photocatalytic Process

The energy gap of photocatalyst is important for photocatalytic processes. As a common substrate, the iron-based photocatalyst has attracted much attention due to its high catalytic activity. While, the basic functional relationship between the mole ratio of Fe2+/Fe3+ in Fe3O4 nanoparticles (NPs) and the energy gap (Eg) is still unknown. this quantitative relationship was built by equations in this study. A series of experiments are carried out and the functional relationship is summarized by UV-Vis diffuse reflectance spectra (DRS) based on Kubelka-Munk theory. Meanwhile, its application for removing the organic dye Congo Red (CR) is examined. Optimum reaction conditions are obtained by orthogonal experiments. This study supplies a basic quantitative relationship between the ratio of Fe2+/Fe3+ in Fe3O4 NPs and its energy gap. It is essential for designing all kinds of novel iron-based photocatalysts.