**Advanced Applications**

**Chapter 8**

Provisional chapter

**Photoelectrochemistry of Hematite**

Photoelectrochemistry of Hematite

Additional information is available at the end of the chapter

It was possible to prepare a hematite film by electrochemical deposition of iron oxide in aqueous solution and its heat treatment at 500C or higher temperature in air. The deposition process of iron oxide film from current and potential pulse methods was mentioned in relation to the equilibrium potential for iron oxide. The hematite in aqueous solution showed a clear photoanodic current due to visible light irradiation. The photo-oxidation response of hematite electrode to organic and inorganic materials in aqueous solution was

DOI: 10.5772/intechopen.73228

Keywords: iron oxide, electrochemical deposition, hematite, photoelectrochemistry,

Hematite (α-Fe2O3), one of iron oxides, has merits of abundance, harmlessness and stability. Hematite is expected to be utilized as a photo-functional material for the purpose of conversion of visible light energy to chemical and electric energy because it is an n-type semiconductor with band gap energy of about 2.0 eV. There are several reports concerning photoelectrochemical characteristics [1–7], photo-oxidation of water [8–15] and photocatalytic water purification [16–21] by using hematite. It is known that oxygen evolution due to photo-oxidation of water could occur on the hematite irradiated with visible light. This may be an interesting and important process from the viewpoint of artificial photosynthesis. Hematite is also one of the candidates for photocatalyst acting under visible light irradiation. Titanium dioxide with band gap energy of about 3.0 eV shows strong photocatalytic performance for environmental purification such as air purification, anti-soiling, self-cleaning, deodorizing, water purification and anti-bacterial [22–23], but it has disadvantage for utilization of visible light energy. In order to use hematite for photocatalysis and photosynthesis effectively, it is necessary to make clear its

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

summarized through the examples of citric acid, Pb2+ and aniline.

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73228

Yasuhisa Maeda

Yasuhisa Maeda

Abstract

visible light

1. Introduction

#### **Photoelectrochemistry of Hematite** Photoelectrochemistry of Hematite

#### Yasuhisa Maeda Yasuhisa Maeda

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73228

#### Abstract

It was possible to prepare a hematite film by electrochemical deposition of iron oxide in aqueous solution and its heat treatment at 500C or higher temperature in air. The deposition process of iron oxide film from current and potential pulse methods was mentioned in relation to the equilibrium potential for iron oxide. The hematite in aqueous solution showed a clear photoanodic current due to visible light irradiation. The photo-oxidation response of hematite electrode to organic and inorganic materials in aqueous solution was summarized through the examples of citric acid, Pb2+ and aniline.

DOI: 10.5772/intechopen.73228

Keywords: iron oxide, electrochemical deposition, hematite, photoelectrochemistry, visible light
