Hematite (α-Fe2O3) is one of the more promising oxide material as anode in photoelectrochemical (PEC) water splitting tandem cells[1]. This material emerge among others since it is cheap, abundant, stable and has a theoretical favourable band gap (2 eV) for solar absorption. However the PEC activity of bare hematite is strongly limited by its low light penetration depth, small hole diffusion length and poor charge transport. Several strategies were reported in order to tune and improve its optical and electronic properties. A key strategy to improve the α-Fe2O3 activity is the optimization of its scale features by nanostructuring or the use of doping elements such as Ti, Pt, Si, Zn and Mg. Both the approaches allow to minimizing the recombination of the photogenerated carries and increasing the plateau current and to tune the optical properties [2-5]. This study explore the synthesis of nanostrucured crystal hematite doped/modified with silicon. The synthetic pathway follow two steps: the solvothermal iron oxide synthesis and the crystal refining by thermal treatment. The first involve the reaction of iron(III) acetate/ethanol and tetramethoxysilane as silicon source. The resulting iron oxide is a goethite α-FeO(OH) enriched phase turned into hematite by a thermal treatment at 550°C. The bare hematite obtained shows an interesting smooth and nanoporous structure, quite different from the original as-sinthesized goethite (fig.1). Moreover, the silicon 10-20% modified hematite show in turn a general elongated structure (fig.2) A systematic analysis of several Si doping loadings were performed. A combination of TEM/STEM, EDX/STEM, Raman spectroscopy and XRD analysis were performed in order to elucidate the local morphology, the crystal defects and the silicon doping grade. Particular attention has been paid to the preferential orientation grow and to the local lattice distortions. These Si-modified hematite nanocrystals are promising materials as photoanode for PEC water splitting.

Si-MODIFIED SOLVOTHERMAL SYTHESIS OF α-Fe2O3 FOR PHOTOELECTROCHEMICAL APPLICATIONS

Santangelo Saveria;Triolo Claudia;
2015-01-01

Abstract

Hematite (α-Fe2O3) is one of the more promising oxide material as anode in photoelectrochemical (PEC) water splitting tandem cells[1]. This material emerge among others since it is cheap, abundant, stable and has a theoretical favourable band gap (2 eV) for solar absorption. However the PEC activity of bare hematite is strongly limited by its low light penetration depth, small hole diffusion length and poor charge transport. Several strategies were reported in order to tune and improve its optical and electronic properties. A key strategy to improve the α-Fe2O3 activity is the optimization of its scale features by nanostructuring or the use of doping elements such as Ti, Pt, Si, Zn and Mg. Both the approaches allow to minimizing the recombination of the photogenerated carries and increasing the plateau current and to tune the optical properties [2-5]. This study explore the synthesis of nanostrucured crystal hematite doped/modified with silicon. The synthetic pathway follow two steps: the solvothermal iron oxide synthesis and the crystal refining by thermal treatment. The first involve the reaction of iron(III) acetate/ethanol and tetramethoxysilane as silicon source. The resulting iron oxide is a goethite α-FeO(OH) enriched phase turned into hematite by a thermal treatment at 550°C. The bare hematite obtained shows an interesting smooth and nanoporous structure, quite different from the original as-sinthesized goethite (fig.1). Moreover, the silicon 10-20% modified hematite show in turn a general elongated structure (fig.2) A systematic analysis of several Si doping loadings were performed. A combination of TEM/STEM, EDX/STEM, Raman spectroscopy and XRD analysis were performed in order to elucidate the local morphology, the crystal defects and the silicon doping grade. Particular attention has been paid to the preferential orientation grow and to the local lattice distortions. These Si-modified hematite nanocrystals are promising materials as photoanode for PEC water splitting.
2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12318/47459
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