Photoelectrochemical water splitting has been considered as an attractive way to transform solar into chemical energy, since photoelectrochemistry of TiO2 was reported in 1972. Hematite (Fe2O3) is a promising material to achieve a higher efficiency because of a smaller band gap, and because it is stable, non-toxic and cheap. However, because (1) low mobility of carriers (∼0.1 cm2 V-1s-1), (2) short hole diffusion lengths, (3) low rate of water oxidation (poor catalysis), (4) high electron-hole recombination rates and (5) inhibited hydrogen evolution due to the conduction band energetics, the reported efficiencies of Fe2O3 are notoriously lower than the theoretically limiting value. Many strategies to address these problems have been developed. Nanostructuring, doping, heterojunctions and surface modification have been used to lower the onset potential, improve the light absorption, charge transport and reduce recombination.
Herein is described the synthesis of two kinds of morphology of Fe2O3 by hydrothermal methods. Doping, homojunctions,and surface modification were attempted to enhance the efficiency of Fe2O3 for photoelectrochemial water oxidation. The impact of these modifications has been analysed by structural, spectroscopic and photoelectrochemical methods. Specifically, a new layered Co-doped Fe2O3/Sn-doped Fe2O3/FTO substrate (Co/Sn/Fe2O3) n-n homojunction photoanode was synthesized, CdS and Cu2O nanoparticles were loaded on the surface of Fe2O3 nanorods by a chemical bath method and amorphous CoOx as water oxidation catalyst was loaded on the surface of Fe2O3 nanorod arrays.
