Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe(2)O(3)) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostructuring approaches have been shown to increase the performance of hematite, but the ideal nanostructure giving high efficiencies for all absorbed light wavelengths remains elusive. Here, we report for the first time mesoporous hematite photoelectodes prepared by a solution-based colloidal method which yield water-splitting photocurrents of 0.56 mA cm(-2) under standard conditions (AM 1.5G 100 mW cm(-2), 1.23 V vs reversible hydrogen electrode, RHE) and over 1.0 mA cm(-2) before the dark current onset (1.55 V vs RHE). The sintering temperature is found to increase the average particle size, and have a drastic effect on the photoactivity. X-ray photoelectron spectroscopy and magnetic measurements using a SQUID magnetometer link this effect to the diffusion and incorporation of dopant atoms from the transparent conducting substrate. In addition, examining the optical properties of the films reveals a considerable change in the absorption coefficient and onset properties, critical aspects for hematite as a solar energy converter, as a function of the sintering temperature. A detailed investigation into hematite's crystal structure using powder X-ray diffraction with Rietveld refinement to account for these effects correlates an increase in a C(3v)-type crystal lattice distortion to the improved optical properties.

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A new design of the universal Mössbauer spectrometer is presented. Hardware solution is based on commercial-available data acquisition devices working on the USB, PCI or PXI platform controlled by the main application running on the personal computer. Final application allows, in addition to Mössbauer spectra accumulation, the detailed analysis of the acquired detector signal in energy and time domains, and also to tune the velocity driving system separately. The experimental results show a high flexibility in various detectors and velocity transducers usage. It is easy to change the way of operation according to the different experimental requirements. This concept can be used with all common spectrometric benches with different velocity transducers, radioactive sources and gamma-ray detectors. This is a new approach in the Mössbauer spectrometer construction.

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