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254 Iron Ores and Iron Oxide Materials

10.1016/j.lfs.2016.09.017

ijms161023482

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73227

#### **Abstract**

Epitaxial films of Rh-substituted α-Fe<sup>2</sup> O3 were fabricated by a pulsed laser deposition technique, and their photoelectrochemical characteristics were investigated for the development of visible light-responsive photoanodes for water splitting. The photocurrent in the films upon irradiation in the visible region was significantly enhanced after Rh substitution. Moreover, a near-infrared photocurrent was clearly observed for Rh:Fe<sup>2</sup> O3 photoanodes, whereas no photoresponse could be detected for the α-Fe<sup>2</sup> O3 films. These improved photoelectrochemical properties are attributed to the increased light absorption due to the hybridization of Rh-4*d* states and O-2*p* states at the valence band maximum. Moreover, Rh substitution also strongly influences the photocarrier transport properties of the films. The electrical conductivity of Rh:Fe<sup>2</sup> O3 is higher than that for α-Fe<sup>2</sup> O3 by two orders of magnitude, which is possibly due to the extended 4*d* orbitals of the Rh3+ ions. Thus, the improved electrical properties may lead to an increased photocurrent by lowering the recombination rate of photogenerated carriers.

**Keywords:** solar water splitting, pulsed laser deposition, photoelectrochemical cell, iron oxides, bandgap engineering
