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In this study, a novel approach was used for the preparation of α-Fe2O3 films via electrodeposition followed by hydrothermal treatment for different time periods. The impacts of the time taken for hydrothermal treatment on the structure and morphology of the electrodeposited films were investigated. According to the X-ray diffraction and Raman spectroscopy results, the alpha structure type showed a unique pure phase. The α-Fe2O3 possessing two phases was revealed for the nanoparticles coated with nanorods by scanning electron microscopy. The energy dispersive X-ray microscopy displayed a remarkable decrease in the intensity of the Tin element due to the formation of nanorods on the nanoparticles. The results showed that the ascending increase in the time for hydrothermal treatment led to significant changes in film morphology and chemical composition with a direct consequence on the photocatalytic performance. The α-Fe2O3 films exhibited high efficiency towards the degradation of methylene blue, which was attributed to its structure. [ABSTRACT FROM AUTHOR]

In this study, the flocculation properties of FucoPol, a bacterial extracellular polysaccharide, were investigated. FucoPol is a high molecular weight polymer and negatively charged due to the presence of glucuronic acid and the acyl groups succinyl and pyruvyl. High flocculation rate values (>70%) were achieved with a low bioflocculant dosage of 1 mg/L, for pH values in the range 3–5 and temperature within 15–20°C. The bioflocculant was also shown to be stable after freezing/thawing and heating up to 100°C. Given the polymer's anionic character, the size of flocs formed and their surface profile, bridging seems to be the main flocculation mechanism of FucoPol. This study demonstrated that FucoPol is a promising natural, biodegradable and biocompatible alternative to the currently used synthetic or inorganic hazardous products, with potential to be used as a novel flocculation agent in several applications, such as water treatment, food or mining. Further studies will involve evaluating the reduction of cation dosage on flocculation efficiency, as well as testing the applicability of FucoPol to flocculate different types of suspended solids, such as, for example, activated carbons, soil solids or yeast cells. [ABSTRACT FROM AUTHOR]

We report the effect of a disperse carbon interlayer between the n-a-Si:H layer and an aluminium zinc oxide (AZO) back contact on the performance of amorphous silicon solar cells. Carbon was incorporated to the AZO film as revealed by x-ray photoelectron spectroscopy and energy-dispersive x-ray analysis. Solar cells fabricated on glass substrates using AZO in the back contact performed better when a disperse carbon interlayer was present in their structure. They exhibited an initial efficiency of 11%, open-circuit voltage Voc = 1.6 V, short-circuit current JSC = 11 mA cm−2 and a filling factor of 63%, that is, a 10% increase in the JSC and 20% increase in the efficiency compared to a standard solar cell. [ABSTRACT FROM AUTHOR]

We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (&#876420 nm) films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times) owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film. [ABSTRACT FROM AUTHOR]

We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (&#876420 nm) films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times) owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film. [ABSTRACT FROM AUTHOR]