The surface characteristics of different carbon materials: activated carbon, carbon felt, glassy carbon and a porous carbon monolith were investigated. The specific surface area was examined by the BET method with N 2 adsorption, the amount and the type of surface oxygen groups by Boehm titration as well as by temperature-programmed desorption (TPD). By comparing the results obtained using BET analysis with those of TPD and the Boehm method, it was found that the number of surface groups was not proportional to the specific surface area. The total amount of oxygen groups, obtained by TPD, is higher than the amount obtained by Boehm's method for porous samples. The inconsistencies between these results originate from the fact that the Boehm method is limited to the determination of acidic and basic groups, whereas TPD provides information on the total number of all surface oxygen groups. In addition, the presence of porosity could reduce the solvent-accessible surface in the Boehm method. The TPD profiles of CO evolution showed the presence of a low temperature maximum, below 650 K, which originates from CO 2 reduction on the carbon material surface.
The effect of microstructural changes caused by mechanical modification on adsorption properties of diatomite samples were investigated. The microstructure has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) while the degree of metal adsorption was evaluated by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP AES). The results show that metal sorption capacity of diatomite is considerably improved after mechanical modification and it can be attributed to amorphysation of the material. Immobilization efficiency increased from 22% for untreated to 81% for the treated sample after 5h at BPR 4.This qualifies natural diatomite as a material for wastewater remediation
Electrochemical characteristics, composition and surface morphology of vinyltriethoxysilane (VTES) coatings on aluminum were investigated. The silane coatings were deposited chemically, by immersion in 2 and 5% VTES, and then cured at 100 • C during 10 or 30 min. Surface morphology of VTES films was analyzed by scanning electron microscopy, while the composition was investigated by X-ray photoelectron spectroscopy. The corrosion stability of silane coatings was determined by electrochemical impedance spectroscopy in 0.03% NaCl. The results obtained were compared with the standardized analysis in the salt spray chamber. The percentage of the corroded area was determined by optical microscopy coupled with image analysis. The influence of VTES concentration and curing time on the corrosion stability of silane films on aluminum was shown. The highest corrosion stability was obtained for silane films deposited from 5% VTES solution with 30 min curing, while the lowest stability was determined for silane films deposited from 2% VTES solution with 10 min curing. Surface analysis suggests that the coatings with the highest corrosion stability are related to the intensive siloxane bonding (Si-O-Si), which is favored by deposition from more concentrated VTES solution.
X-Ant-Em instrument operated at 300 kV. The temperature dependent resistivities were measured with a van der Pauw geometry on a Quantum Design physical property measurement system. The XAS experiments were performed on the XTreme beamline at Swiss Light Source. [45]
Functional oxides on silicon have been the subject of in-depth research for more than 20 years. Much of this research has been focused on the quality of the integration of materials due to their intrinsic thermodynamic incompatibility, which has hindered the flourishing of the field of research. Nevertheless, growth of epitaxial transition metal oxides on silicon with a sharp interface has been achieved by elaborated kinetically controlled sequential deposition while the crystalline quality of different functional oxides has been considerably improved. In this Research Update, we focus on three applications in which epitaxial ferroelectric oxides on silicon are at the forefront, and in each of these applications, other aspects of the integration of materials play an important role. These are the fields of piezoelectric microelectromechanical system devices, electro-optical components, and catalysis. The overview is supported by a brief analysis of the synthesis processes that enable epitaxial growth of oxides on silicon. This Research Update concludes with a theoretical description of the interfaces and the possibility of manipulating their electronic structure to achieve the desired coupling between (ferroelectric) oxides and semiconductors, which opens up a remarkable perspective for many advanced applications.
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