Paving the road toward the use of β-Fe2O3 in solar water splitting: Raman identification, phase transformation and strategies for phase stabilization

Although β-Fe2O3 has a high theoretical solar-to-hydrogen efficiency because of its narrow band gap, the study of β-Fe2O3 photoanodes for water splitting is elusive as a result of their metastable nature. Raman identification of β-Fe2O3 is theoretically and experimentally investigated in this study for the first time, thus clarifying the debate about its Raman spectrum in the literature. Phase transformation of β-Fe2O3 to α-Fe2O3 was found to potentially take place under laser and electron irradiation as well as annealing. Herein, phase transformation of β-Fe2O3 to α-Fe2O3 was inhibited by introduction of Zr doping, and β-Fe2O3 was found to withstand a higher annealing temperature without any phase transformation. The solar water splitting photocurrent of the Zr-doped β-Fe2O3 photoanode was increased by 500% compared to that of the pure β-Fe2O3 photoanode. Additionally, Zr-doped β-Fe2O3 exhibited very good stability during the process of solar water splitting. These results indicate that by improving its thermal stability, metastable β-Fe2O3 film is a promising photoanode for solar water splitting.

Enhanced photocatalytic water splitting of a SILAR deposited α-Fe2O3 film on TiO2 nanoparticles

Optimization of photoelectrochemical water splitting by a composite of SILAR-deposited α-Fe2O3 thin film on a substrate of TiO2 nanoparticles.

C2H5OH and LPG sensing properties of -Fe2O3 microflowers prepared by hydrothermal route

The flower-like micron-structure of α-Fe2O3 was synthesized via hydrothermal treatment at 140 C for 24 h using Fe(NO3)3.9H2O and Na2SO4 as the precursors. A thin film constructed by the as-prepared material was created by spin coating technique. The structure, morphology, and composition of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). The α-Fe2O3 microflowers (MFs) with average diameter of several micrometers are assembled of nanorods which possess average diameter and length of 40 nm and hundred nm, respectively. The gas sensing properties of α-Fe2O3 film were tested with ethanol (C2H5OH) and liquefied petroleum gas (LPG) at the operating temperatures of 225–400 °C. The sensor response of the α-Fe2O3 film reached highest sensitivity to C2H5OH and LPG at 275 C and 350 °C, respectively. The thin film exhibited higher sensitivity and lower working temperature to C2H5OH than those to LPG. The film can detect minimum concentration of 250 ppm C2H5OH. The response time of the film to C2H5OH is approximately 30 s.