Metastable-phase β-Fe2O3 photoanodes for solar water splitting with durability exceeding 100 h

Planar films of pure and Ti4+-doped β-Fe2O3 were prepared by a spray pyrolysis method. X-ray diffraction patterns and Raman spectra of the metastable β-Fe2O3 film showed that its thermal stability was significantly improved because of covalent bonds in the interfaces between the film and substrate, while only weak Van der Waals bonds existed at the interfaces within the particle-assembled β-Fe2O3 film prepared by electrophoretic deposition. The as-prepared planar films were thus able to withstand higher annealing temperature and stronger laser irradiation power in comparison with the β-Fe2O3 particle-assembly. Ti4+ doping was used to increase the concentration of carriers in the metastable β-Fe2O3 film. Compared with pure β-Fe2O3 photoanodes, the highest saturated photocurrent for water splitting over the Ti4+-doped β-Fe2O3 photoanode was increased by a factor of approximately three. The β-Fe2O3 photoanode exhibited photochemical stability for water splitting for a duration exceeding 100 h, which indicates its important potential application in solar energy conversion.