The development of catalysts for high-efficient hydrogen evolution reaction (HER) is important for future sustainable energy conversion. Herein, porous carbon-supported PtNi alloy catalysts were fabricated by ion beam...
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The development of catalysts for high-efficient hydrogen evolution reaction (HER) is important for future sustainable energy conversion. Herein, porous carbon-supported PtNi alloy catalysts were fabricated by ion beam sputtering and ultrasonic-assisted electrochemical corrosion dealloying methods, and their performances toward the catalysis of HER were evaluated. The effects of corrosion dealloying on the hydrogen evolution activity, as well as stability, phase structure, surface composition, and active sites of PtNi alloys were analyzed by various analytical methods combined with orthogonal experiments. The results showed increased catalytic activity of HER by 51.39% after corrosion of the material in 0.2 mol/L H2SO4 at 40 degrees c for 0.5 h. The hydrogen evolution deteriorated as Pt-loading decreased by 25.83%, and corrosion temperature displayed significant influence. The pore structure of the catalyst surface raised the relative content of the exposed Pt element, and the zero-dimensional defect generated by the Ni atom deletion led to promotion in reaction area and active sites on the catalyst surface. The interplanar spacing of alloys (NiPt) was below 3%-6% of the standard value, and the lattice compressive strain of Pt was the reason that led to improved catalytic performance of PtNi alloy catalysts. The binding energy of the Pt 4f7/2 decreased by 0.74 eV, leading to enhanced electrochemical active sites and promoted hydrogen release. (c) 2021 Elsevier B.V. All rights reserved.
Electrochemical cO2 reduction to produce valuable c-2 products is attractive but still suffers with relatively poor selectivity and stability at high current densities, mainly due to the low efficiency in the coupling...
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Electrochemical cO2 reduction to produce valuable c-2 products is attractive but still suffers with relatively poor selectivity and stability at high current densities, mainly due to the low efficiency in the coupling of two *cO intermediates. Herein, it is demonstrated that high-density nitrogen vacancies formed on cubiccopper nitrite (cu3Nx) feature as efficient electrocatalyticcenters for cO-cO coupling to form the key OccO* intermediate toward c-2 products. cu3Nx with different nitrogen densities are fabricated by an electrochemical lithium tuning strategy, and density functional theory calculations indicate that the adsorption energies of cO* and the energy barriers of forming key c-2 intermediates are strongly correlated with nitrogen vacancy density. The cu3Nx catalyst with abundant nitrogen vacancies presents one of the highest Faradaic efficiencies toward c-2 products of 81.7 +/- 2.3% at -1.15 V versus reversible hydrogen electrode (without ohmiccorrection), corresponding to the partial current density for c-2 production as -307 +/- 9 mA cm(-2). An outstanding electrochemical stability is also demonstrated at high current densities, substantially exceeding cuOx catalysts with oxygen vacancies. The work suggests an attractive approach to create stable anion vacancies as catalyticcenters toward multicarbon products in electrochemical cO2 reduction.
We demonstrated the efficient coupling of BiFeO3 (BFO) ferroelectric material within the carbon-sulfur (c-S) composite cathode, where polysulfides are trapped in BFO mesh, reducing the polysulfide shuttle impact, and ...
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We demonstrated the efficient coupling of BiFeO3 (BFO) ferroelectric material within the carbon-sulfur (c-S) composite cathode, where polysulfides are trapped in BFO mesh, reducing the polysulfide shuttle impact, and thus resulting in an improved cyclic performance and an increase in capacity in Li-S batteries. Here, the built-in internal field due to BFO enhances polysulfide trapping. The observation of a difference in the diffusion behavior of polysulfides in BFO-coupled composites suggests more efficient trapping in BFO-modified c-S electrodes compared to pristine c-S composite cathodes. The X-ray diffraction results of BFO-c-S composite cathodes show an orthorhombic structure, while Raman spectra substantiate efficient coupling of BFO in c-S composites, in agreement with SEM images, showing the interconnected network of submicron-size sulfur composites. Two plateaus were observed at 1.75 V and 2.1 V in the charge/discharge characteristics of BFO-c-S composite cathodes. The observed capacity of ~1600 mAh g(-1) in a 1.5-2.5 V operating window for BFO30-c-10-S-60 composite cathodes, and the high cyclic stability substantiate the superior performance of the designed cathode materials due to the efficient reduction in the polysulfide shuttle effect in these composite cathodes.
In this paper, the tensile damage and fracture behavior of carbon fiber reinforced silicon carbide (c/Sic) minicomposites with single- and multiple-layer interphases are investigated. The effect of the interphase on t...
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In this paper, the tensile damage and fracture behavior of carbon fiber reinforced silicon carbide (c/Sic) minicomposites with single- and multiple-layer interphases are investigated. The effect of the interphase on the tensile damage and fracture behavior of c/Sic minicomposites is analyzed. The evolution of matrix cracking under the tensile load of the c/Sic minicomposite with a notch is observed using the digital image correlation (DIc) method. The damage evolution process of the c/Sic minicomposite can be divided into four main stages, namely, (1) an elastic response coupled with partial re-opening of thermal microcracking;(2) multiple matrix microcracking perpendicular to the applied loading;(3) crack opening and related fiber/matrix, bundle/matrix, and inter-bundle debonding;and (4) progressive transfer of the load to the fibers and gradual fiber failure until composite failure/fracture. On the fracture surface, a large number of fibers pulling out of the samples with both single-layer and multi-layer interphases can be clearly observed.
This study elucidates the impact of the microstructure of Fe-16cr-0.2c on oxide layer formation at 650 degrees c in Ar0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. Th...
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This study elucidates the impact of the microstructure of Fe-16cr-0.2c on oxide layer formation at 650 degrees c in Ar0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. The samples were characterised in detail from microstructural and chemical perspectives using scanning electron microscopy (SEM), X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microstructural modification of the alloy by heat-treatment was advantageous. It was found that cr-carbides support chromia formation and reduce sulphidation when their area fraction is low and diameter is small.
c-14 contained in Hull waste is one of the most important radionuclides in the safety assessment of transuranic (TRU) waste disposal. For more realistic safety assessment, it is important to clarify the release mechan...
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c-14 contained in Hull waste is one of the most important radionuclides in the safety assessment of transuranic (TRU) waste disposal. For more realistic safety assessment, it is important to clarify the release mechanism and chemical species of c-14 from Hull waste. In this research, leaching tests were conducted using an irradiated Zry cladding tube from a boiling-water reactor (BWR) to obtain leaching data and to investigate the relationship between Zry metal corrosion and c-14 release behavior. Both organic and inorganicc-14 compounds existed in the the liquid phase, and some c-14 moved to the gaseous phase. The release rate of c-14 obtained from the BWR cladding tube after two-year leaching tests was lower than the release rate from a pressurize water reactor (PWR) cladding tube. It is considered that the BWR cladding tube used in this test did not easily corrode since it used a comparatively new material. The release rate of c-14 was slightly lower as compared with the corrosion rate of unirradiated Zry. This is thought to be the result of improved corrosion resistance conferred by neutron irradiation, which encouraged the dissolution of grain boundary precipitation elements, such as Fe, cr, and Ni, into the crystal grains. The leaching tests will be continued for 10 years.
Needle optimization is widely used in visible and infrared region, but it is rarely utilized in X-ray and extreme ultraviolet waveband. We use Needle optimization to design Pt/c X-ray supermirrors, and the grazing inc...
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Needle optimization is widely used in visible and infrared region, but it is rarely utilized in X-ray and extreme ultraviolet waveband. We use Needle optimization to design Pt/c X-ray supermirrors, and the grazing incidence angles are 1.0, 1.4, and 1.7 degree, respectively. A modified target is introduced into optilayer software. A good result is obtained by Optilayer software combined with IMD software. The difference of design results between block method and needle optimization is discussed.
Gas-phase direct catalyticcoupling of 1,4-butanediol (1,4-BDO) dehydrogenation and acetophenone (AP) hydrogenation was performed on MgO/carbon supported cu nanoparticles. The coupling reaction process completely avoi...
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Gas-phase direct catalyticcoupling of 1,4-butanediol (1,4-BDO) dehydrogenation and acetophenone (AP) hydrogenation was performed on MgO/carbon supported cu nanoparticles. The coupling reaction process completely avoids the practice of hydrogen supply and efficiently utilizes the liberated in-situ H2 from the 1,4BDO dehydrogenation for the highly selective hydrogenation of AP. A series of cu catalysts (5-20 wt%) synthesized by wet-impregnation method and well distinguished by BET, IcP-MS, p-XRD, H2-TPR, TPD, FE-SEM, XPS and HR-TEM techniques. Among synthesized catalysts, 10cu/c-MgO catalyst exhibits outstanding catalytic performance with the maximum conversion of 1,4-BDO (98 %), and AP (95 %). Dramatically, steady gamma-butyrolactone (>= 99 %) and 1-phenylethanol (99 %) selectivity are observed over 10 wt%cu/MgO/carbon catalyst. Moreover, 10 wt% cu loading exhibited nearly stable activity up to 30 h time-on-stream without any significant deactivation. The presence of biomorphic MgO/carbon derived from rice grains prevents the sintering of copper particles and improves the catalyst stability. The unusual enhancement in the catalytic performance can be typically attributed to the uniform dispersion of cu nanoparticles and the presence of an intense amount of surface basic sites on the MgO/carbon support.
This study investigated the oxidation behaviours of a TiAl (TNM) alloy oxidized at 650 ?c in argon and oxygen. The oxidation mass gains were similar in both atmospheres up to 200 h of oxidation. Between 200 and 500 h,...
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This study investigated the oxidation behaviours of a TiAl (TNM) alloy oxidized at 650 ?c in argon and oxygen. The oxidation mass gains were similar in both atmospheres up to 200 h of oxidation. Between 200 and 500 h, the mass gains increased by 20 % in the O2 atmosphere. This study examined the triplex oxide scales of outer (Ti?Al) O layer-by-layer and Mo/Nb-rich TiAl oxides on the TNM alloy after oxidation in Ar and O2. The scale structures formed in Ar and O2 were similar but differed from those formed in air, and the respective TNM samples? oxidation behaviours were different.
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