Hybrids of bimetallic NiFex crystalline nanoparticles homogeneously embedded in ordered mesoporous carbon (OMC) for electrochemical hydrogen storage applications were fabricated through wet impregnation and H2 reduction techniques. The size and distribution of NiFex nanoparticles of NiFex/OMC hybrids can be tuned by controlling the molar ratio of Ni : Fe, with the smallest diameter of 4.7 nm for the NiFe2 alloy nanoparticles. The effects of NiFex nanoparticle incorporation into the OMC matrix on the surface area, pore volume, pore size and electrochemical hydrogen storage performances were comparatively investigated using adsorption isotherms of nitrogen, electrochemical impedance spectroscopy, potentiodynamic polarization, cyclic voltammetry and galvanostatic charge–discharge techniques. With the molar ratio of Ni : Fe decreasing, the discharge capacity and the cycle performance of the NiFex/OMC hybrids display a notable improvement due to the homogenous dispersion of NiFex nanoparticles, higher surface area, larger mesopore volume, lower defect ration, and smaller charge-transfer resistance. The NiFe2/OMC samples display greatly improved electrochemical hydrogen storage discharge capacity of 418 mA h g−1, which is about four times as high as that of the pure OMC electrode.
Toxic mercury emissions from various industrial sources, especially coal combustion, have become an increasing concern in recent years, and effective methods of removing these emissions from coal combustion flue gases are being sought. In this study, fly-ash-modified bamboo-shell carbon blacks were prepared, and the properties and mercury removal abilities of the prepared carbon blacks were evaluated. The fly ash acted as a support for the carbon structure during the carbon black preparation, and demonstrated the ability to fix a portion of the carbon contained in volatile compounds during carbonization, resulting in a higher carbon yield of the carbon black containing fly ash; it had a higher BET surface area and a higher mercury removal ability than carbon black without fly ash. Strong pore structure, in the range of 1000–10000 nm, appeared after the addition of fly ash, which became stronger with higher fly-ash content. Additionally, the mercury compounds generated through the catalytic effect of fly ash (around 200 °C) had lower thermal stabilities than those generated on carbon (280 °C), according to the TPDD experiments, indicating that the addition of fly ash was favorable for the recycling of the mercury compounds and the regeneration of used carbon black.
By controllable heteroatomic interface engineering, a MOF-derived gradient N,P-doped C@N-C@N,P-C heterostructure with built-in electric field was acquired.
Limited by the relatively low specific surface area and small quantity of active sites of semiconductor photocatalysts, the photocatalytic nitrogen fixation performance remains very low, as expected. Herein, rutile titanium dioxide (TiO2) nanoparticles with large specific surface area and abundant oxygen vacancy were designed for photocatalytic nitrogen fixation. The TiO2 photocatalysts exhibit high photocatalytic performance for nitrogen fixation in the presence of methanol as the hole scavenger, with the highest ammonia generation rate of 116 μmol·g–1·h–1, exceeding 6.5 times that of P25. This study provides a simple and facile method to prepare highly reactive TiO2 photocatalysts for enhanced photocatalytic nitrogen fixation performance.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
FeWO4 (FWO) nanocrystals were prepared at 180 °C by a simple hydrothermal method, and carbon-coated FWO (FWO/C) was obtained at 550 °C using pyrrole as a carbon source. The FWO/C obtained from the product hydrothermally treated for 5 h exhibits reversible capacities of 771.6, 743.8, 670.6, 532.6, 342.2, and 184.0 mAh g–1 at the current densities of 100, 200, 400, 800, 1600, and 3200 mA g–1, respectively, whereas that from the product treated for 0.5 h achieves a reversible capacity of 205.9 mAh g–1 after cycling 200 times at a current density of 800 mA g–1. The excellent electrochemical performance of the FWO/C results from the combination of the nanocrystals with good electron transport performance and the nitrogen-doped carbon coating.
ABSTRACT In this study, high-quality SrMnO 3 (001) film was grown on a SrTiO 3 (001) substrate using a 4 N purity target by 90° off-axis RF magnetron sputtering. In this study, the influence of the plasma center and surrounding positions on the growth of the SrMnO 3 film was investigated under different sputtering temperatures and working pressure conditions. The results revealed that the SrMnO 3 film exhibited the best crystallinity at the sputtering center under a high working pressure (135 mTorr), high substrate temperature (750 °C), and Ar to O ratio of 1:1. After investigating the relationship between the growth rate and the working pressure through the Alpha step, the film was grown at a lower sputtering rate of 2 nm/min. X-ray diffraction confirmed that the SrMnO 3 film was epitaxially grown on the SrTiO 3 substrate with an orientation relationship of SrMnO 3 (001)//SrTiO 3 (001). The growth state of SrMnO 3 on the crystal SrTiO 3 substrate was investigated by scanning electron microscopy (SEM); the results revealed that the surface was smooth and compact. In addition, the atomic force microscopy results were consistent with the SEM result; the results revealed that the surface of the film was atomically flat, and the atomic level flatness was 0.906 nm. Furthermore, the contact angle measurement results revealed that the film and substrate surface energy were almost similar and exhibited similar adhesion and internal stress. In addition, energy-dispersive X-ray spectroscopy analysis revealed that the atomic composition ratio in the high-temperature sputtered SrMnO 3 film was consistent with the stoichiometric ratio of SrMnO 3 . The scope and results of this study will lay a foundation on the further research of the performance of SrMnO 3 film.
In recent years, the optical behavior of complex oxides are being increasingly used in light-harvesting applications. Perovskites are promising candidates for photovoltaic, photocatalytic, and optoelectric applications because of tunable band gaps and other unique properties such as fer-roelectricity To study the optical behavior of ferromagnetic-ferroelectric oxides, SrMnO 3 (SMO 3 ) targets intended for use in magnetron sputtering were prepared using SrCO 3 (99.99%) and Mn 2 O 3 (99.99%) powders by a two-step solid reaction method. Experiments were performed at various temperatures to determine the optimum calcination temperature of the SMO 3 powder (1000 °C) and optimum sintering temperature of the prepared target (1300 °C), in an effort to optimize the preparation process of the target at the laboratory scale and reduce the cost of the target by more than 20-fold. Samples of the ground powder were calcined at 800, 1000, 1200, and 1300 °C for 10 h, and the resultant targets were pressed into 1 -in molds after grinding and subsequently sintered at the same temperatures at which the corresponding powders were calcined, i.e., at 800, 1000, 1200, and 1300 °Cfor 48 h. The microcrystalline state of the powders was observed by scanning electron microscopy. The prepared targets were analyzed by X-ray diffraction, and the results were compared with the powder diffraction file card of hexagonal SMO 3 to determine the optimum calcination temperature and sintering temperature of the powder formulation. Finally, the Vickers hardness values of the targets were measured, and the optimum target preparation process was determined.
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