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41.
Highly Conformal Deposition of an Ultrathin FeOOH Layer on a Hematite Nanostructure for Efficient Solar Water Splitting 下载免费PDF全文
Dr. Jae Young Kim Dr. Duck Hyun Youn Kyoungwoong Kang Prof. Jae Sung Lee 《Angewandte Chemie (International ed. in English)》2016,55(36):10854-10858
An ultrathin (ca. 2 nm) amorphous FeOOH overlayer was deposited conformally on a hematite nanostructure by a simple solution‐based precipitation method, to generate an oxygen evolution cocatalyst for efficient solar water splitting. This uniform and highly conformal coating of the ultrathin metal oxyhydroxide is rare and is distinguished from the layers prepared by other conventional methods. With the FeOOH overlayer as the cocatalyst, the water oxidation photocurrent of hematite increased by a factor of approximately two and the onset potential shifted in the cathodic direction by 0.12 V under 1 sun illumination. The enhanced performance was attributed to the improved water oxidation kinetics and the passivation of the surface states of the hematite. 相似文献
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The adsorption measurements of hydrolyzed polyacrylamide (HPAM) onto hematite suspension are carried out to study the dynamics of the polymer adsorption onto the suspension particles and to investigate the mode of the polymer adsorption. The polymer is found to show much affinity for the adsorption because of the opposite charges possessed by the polymeric flocculant and the suspension particles. Various adsorption parameters such as adsorption coefficient, the rate constants for the adsorption and desorption, are evaluated with the help of a recently proposed kinetic scheme. It is found that the extent of adsorption and the adsorption rate are adequately affected by increasing the pH of the suspension while, unexpectedly, the adsorption is found to show only a marginal increase on addition of Na2SO4. Both the amount of the adsorbed polymer and the adsorption rate are also found to increase with the degree of hydrolysis of the polyelectrolyte. 相似文献
44.
Joseína Moutinho Tavares de Souza Maria do Carmo Rangel 《Reaction Kinetics and Catalysis Letters》2002,77(1):29-34
The replacement of chromium by aluminium in high temperature shift catalysts was investigated. It was found that aluminium-doped hematite is a convenient candidate as an environmental friendly catalyst. 相似文献
45.
Kazuhiko Kandori Akemi Yasukawa Tatsuo Ishikawa 《Journal of colloid and interface science》1996,180(2):446
The structure and properties of hematite particles obtained by hydrolysis of ferric chloride solution doped with various kinds of amines were examined by TEM, XRD, TG-DTA, N2and H2O adsorption, and zeta potential measurements. The shape of precipitates was concentration dependent; they changed from large spheres (diameter: ca. 820 nm) to cubes (edge length: ca. 400 nm) via double-spheres (long axis length: ca. 600 nm) with increasing monoamine concentrations. This effect was enhanced by increasing their pKavalues. Much pronounced effects of di- and triamines on the particle formation were observed; cubic and double-spherical particles were obtained at a much lower concentration of di- and triamines and small spherical (diameter: ca. 100 nm) and diamond-like (long axis length: ca. 100 nm) particles were further produced at higher concentration. It was suggested that the acceleration of the rate of phase transformation from β-FeOOH to hematite induced by amines plays an important role for producing fairly uniform hematite particles with different shape and size. The hematite particles produced with amines contained small amounts of OH−ions in the lattice but were confirmed to be nearly single crystal. 相似文献
46.
Precipitation phenomena in aqueous solutions containing FeCl3 and NaH2PO2 in varying concentrations have been studied at 245 °C. The composition and the morphology of the resulting particles depended strongly on the concentration ratios of the reacting ions. In the presence of small amounts of NaH2PO2 only hematite formed of different particle shapes. An increased addition of hypophosphite ions had two effects: first, anions of phosphorus were incorporated in the solids and, second, ferric ions were reduced to ferrous ions giving a variety of products.Supported by the Electric Power Research Institute, Contract RP-966-2.On leave from Yokohama City University, Japan. 相似文献
47.
Kazuya Okada 《Molecular physics》2017,115(6):683-701
We have investigated the aggregate structure of a suspension composed of magnetic particles with a cubic geometry by means of Monte Carlo simulations. From the viewpoint of application to the technology of surface modification, we have considered a quasi-two-dimensional suspension in thermodynamic equilibrium. As the magnetic interaction strength is increased, the effects of the thermal energy are reduced and the particles tend to aggregate together. These aggregates of cubic particles are not chain-like, but are designated as closely packed clusters. An applied magnetic field tends to enhance the formation of clusters along the field direction but does not significantly regularise the internal structure of the cluster. This is mainly due to the preference of a face-to-face contact configuration for the alignment of particles with cubic geometry. The regime of the internal structure of aggregates has a significant effect on the characteristics of the alignment of the magnetic moments with regard to the external magnetic field direction. Our simulations indicate that larger closely packed clusters are formed with increasing volumetric fraction, whereas the internal structure of the closely packed clusters is not found to be significantly influenced by the change in the volumetric fraction. 相似文献
48.
Hematite has been widely studied for catalytic water splitting, but the role of the interactions between catalytic sites is unknown. In this paper, we calculate the oxygen evolution reaction free energies and the surface adsorption distribution using a combination of density functional theory and Monte Carlo simulations to “cover the waterfront,” or cover a wide range of properties with a simulation of the hematite surface under working conditions. First, we show that modeling noninteracting catalytic sites provides a poor explanation of hematite's slow reaction kinetics. The interactions between the catalytic site may hinder catalysis through the strong interactions of *OH2 and *OOH intermediates, which cause the reaction to revert back to the *O intermediate. Hence, neighboring interactions may be a possible reason for the abundant, experimentally observed *O intermediate on the surface. This study demonstrates how neighboring sites impact the energy required for catalytic steps, thus providing new avenues to improve catalysis by controlling neighboring site interactions. 相似文献
49.
Mohamad Mohsen Momeni Akbar Hallaj Yousef Ghayeb Robabeh Bagheri Zhenlun Song Hossein Farrokhpour 《应用有机金属化学》2019,33(9)
Palladium particles were deposited on hematite nanotube surfaces via a facile photodeposition method. Anodization method was then used for direct vertical growth of hematite nanotube arrays (HNTs) on a pretreated iron substrate. Field emission scanning electron microscopy, X‐ray diffraction, diffraction reflection spectroscopy and X‐ray photoelectron spectroscopy analyses were then used to carry out morphological and structural investigations. Compared with the bare HNTs, Pd‐decorated hematite films (Pd/HNTs) exhibit intense visible light absorption and show a red shift of the band edge. Pd/HNTs are more photoelectrochemically active than the non‐decorated films, according to chronoamperometry measurements. Thus, a promising methodology has been developed for the design of a simple and effective photoelectrode for application in photoelectrochemical water splitting systems. 相似文献
50.
Riham Michelle Morcos Alexandra Navrotsky 《Journal of Thermal Analysis and Calorimetry》2009,96(2):353-361
Differential scanning and high temperature reaction calorimetry have been used to characterize a series of natural iron ore
and flux samples commonly used during iron ore sintering. Most iron ore samples were shown to contain measurable quantities
of goethite, with a characteristic dehydration peak in DSC and TG between 200 and 400°C. At higher temperatures, all samples
decomposed to produce magnetite with an accompanying mass loss in the TG profile due to the evolution of oxygen.
High temperature reaction calorimetry has been used to measure the heat of solution of the ore in the melt formed during iron
ore sintering. The dehydration and calcination of iron ore and flux samples was also examined using high-temperature reaction
calorimetry. The results support the DSC/TG findings. 相似文献