5. Conclusion

Figure 25. Mott-Schottky plots of the hematite electrode (a), the polyaniline-glassy carbon electrode (b) and the polyaniline-hematite electrode (c) in 0.1 M aqueous HClO4 solution. Hematite was prepared from thermal oxidation of

iron at 600C for 3 h in air.

172 Iron Ores and Iron Oxide Materials

As a preparation method of hematite film, the process for electrochemical deposition of iron oxide and its heat treatment in air was mentioned in relation to the equilibrium potential of iron oxide in aqueous solution. The current and potential pulse electrolysis may be useful in deposition of homogeneous iron oxide film. The hematite from the heat treatment of iron oxide at 500 C or higher temperature in air showed a clear photocurrent response and brought the photo-oxidation of chemical species such as citric acid, Pb2+ ion and aniline under visible light irradiation. On the hematite electrode in aqueous solution containing organic materials under visible light irradiation, photo-oxidation processing of organic materials with suppression of water photo-oxidation may be possible. This will lead to application of photo functionality of hematite to a new method for organic synthesis.
