The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Zaoxiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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toward the design of interstitial Nonmetals co doping for mg based hydrides as hydrogen storage material
Journal of Materials Research, 2018Co-Authors: Luying Zhu, Fusheng Yang, Serge Nyallang Nyamsi, Ekambaram Porpatham, Zaoxiao ZhangAbstract:The strong interactions between Mg and Ni/NiH4 are attributed to harsh operating conditions and difficulties for H2 release, restricting the practical applications of the Mg-based hydrides. In this study, a new method of interstitial Nonmetals co-doping was proposed to reduce the strong interactions. The calculation results showed that the method of interstitial Nonmetals co-doping causes a more significant reduction in the thermal stability of Mg-based hydrides, as compared with the methods of either single transition metal or Nonmetal doping. To determine the influence mechanism, a theoretical study was conducted based on the first-principles calculations. The computations demonstrated that the criss-cross action between B–Ni and N–Mg bonds weakens the bonding effects between Mg and Ni/NiH4. Besides, the mutual interactions between Nonmetals and H atoms could weaken Ni–H bonding effects and stimulate the breaking of stable NiH4 clusters, thereby facilitating the release of H2 from the hydride.
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insight into destabilization mechanism of mg based hydrides interstitially co doped with Nonmetals a dft study
European Physical Journal B, 2018Co-Authors: Luying Zhu, Fusheng Yang, Zaoxiao Zhang, Serge Nyallang NyamsiAbstract:Mg-based metal hydride is one of the most promising materials for hydrogen energy storage. However, the high thermal stability due to strong bonding effects between the atoms limits its practical application. In order to reduce the thermal stability, a method of doping double Nonmetals into Mg-based system was proposed in this study. The density functional theory (DFT) calculation results showed that the thermal stabilities of both the B-N co-doped Mg-based alloy and its hydride are reduced compared with pure Mg-based system. The relative formation enthalpies of the alloy and its hydride are 0.323 and 0.595 eV atom−1, respectively. The values are much higher than those for either singly B- or N-doped Mg-based system. The more significant destabilization by doping double Nonmetal elements than single element is mainly attributed to a dual effect in weakening Mg–Ni/NiH4 bonds, caused by criss-cross interactions between B–Ni and N–Mg bonds.
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improvement in hydrogen storage characteristics of mg based metal hydrides by doping Nonmetals with high electronegativity a first principle study
Computational Materials Science, 2013Co-Authors: Fusheng Yang, Serge Nyallang Nyamsi, Zewei Bao, Zaoxiao ZhangAbstract:Abstract The effects of a small amount of Nonmetal elements (N, F and Cl) with high electronegativity interstitially doping on improving the hydrogen storage characteristics of Mg-based metal hydrides were systematically investigated by first-principle calculations in this paper. The interstitial positions which the doping elements easily occupied were firstly determined. The calculation results showed that these elements are most likely to hold the center position of octahedral sites with two Ni and four Mg atoms. Based on this, the crystal structures, thermal stability, dehydrogenation energy and electronic structures of all the crystals, including Mg2Ni, Mg2NiN0.5, Mg2NiF0.5, Mg2NiCl0.5 and their hydrides, were further investigated. The Nonmetals with high electronegativity exhibit the favorable effects on the characteristics of Mg-based metal hydrides. Doping F significantly reduces the dehydrogenation energy of Mg2NiH4 by about 25%, because of the strong hybridization between F and H atoms. When doping Cl into Mg2Ni and Mg2NiH4, the formation enthalpies decrease respectively by 0.047 and 0.024 eV atom−1, due to the reduction of integral intensity of the bonding electron. Among the three elements, N has the best effects on improving both kinetics and thermodynamics. Doping N not only causes the formation enthalpies of Mg2Ni and its hydride to decrease by 0.215 and 0.141 eV atom−1 respectively, but also reduces the dehydrogenation energy of Mg2NiH4.
N. Vinothkumar - One of the best experts on this subject based on the ideXlab platform.
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Enhanced photocatalytic hydrogen production from water–methanol mixture using cerium and Nonmetals (B/C/N/S) co-doped titanium dioxide
Materials for Renewable and Sustainable Energy, 2014Co-Authors: N. Vinothkumar, Mahuya DeAbstract:In the present study, photocatalytic hydrogen production from water/methanol solution was investigated over cerium and Nonmetal (B/C/N/S) co-doped titanium dioxide catalyst under visible light irradiation. The cerium and Nonmetal co-doped titania photocatalysts were prepared by co-precipitation and characterized by surface area and pore size analysis, X-ray diffraction analysis, diffuse reflectance UV–Vis spectroscopy analysis, and photoluminescence analysis. The UV–Visible spectra showed that incorporation of cerium and Nonmetals to TiO_2 resulted in narrow band gap and improved absorption of visible light. The band gap energy of co-doped samples depended on the properties of Nonmetals. Photoluminescence studies showed that the radiative recombination rates of photogenerated electron–hole pairs were effectively suppressed by the addition of cerium and Nonmetals and contributed to higher activity. The highest hydrogen production of 206 μmol/h was obtained for Ce–N–TiO_2 sample, which can be attributed to the higher surface area, higher absorption of visible light, and higher separation efficiency of electron–hole pairs in Ce–N–TiO_2.
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enhanced photocatalytic hydrogen production from water methanol mixture using cerium and Nonmetals b c n s co doped titanium dioxide
Materials for Renewable and Sustainable Energy, 2014Co-Authors: N. VinothkumarAbstract:In the present study, photocatalytic hydrogen production from water/methanol solution was investigated over cerium and Nonmetal (B/C/N/S) co-doped titanium dioxide catalyst under visible light irradiation. The cerium and Nonmetal co-doped titania photocatalysts were prepared by co-precipitation and characterized by surface area and pore size analysis, X-ray diffraction analysis, diffuse reflectance UV–Vis spectroscopy analysis, and photoluminescence analysis. The UV–Visible spectra showed that incorporation of cerium and Nonmetals to TiO2 resulted in narrow band gap and improved absorption of visible light. The band gap energy of co-doped samples depended on the properties of Nonmetals. Photoluminescence studies showed that the radiative recombination rates of photogenerated electron–hole pairs were effectively suppressed by the addition of cerium and Nonmetals and contributed to higher activity. The highest hydrogen production of 206 μmol/h was obtained for Ce–N–TiO2 sample, which can be attributed to the higher surface area, higher absorption of visible light, and higher separation efficiency of electron–hole pairs in Ce–N–TiO2.
Yushan Xing - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of polypropylene composites reinforced by Nonmetals recycled from waste printed circuit boards during tensile testing
Journal of Applied Polymer Science, 2009Co-Authors: Yanhong Zheng, Chujiang Cai, Zhigang Shen, Yushan XingAbstract:A great amount of work has been done over the past few years to reuse the Nonmetals recycled from waste printed circuit boards in polypropylene (PP) composites. This is because of the very fast generation rate of Nonmetal pollution in the world each year and the very fast growing rate of PP applications in industries. This work focuses on the dynamic effects of Nonmetals of different particle sizes on the tensile properties and reinforcing mechanisms of Nonmetal/PP composites by in situ scanning electron microscopy tensile testing. The observed results show that the dominant deformation mechanism in pure PP is shear yielding. When fine Nonmetals are filled into PP, mass microcracks are initiated. The glass fibers first resist the cracks and undertake the loading when they propagate. The crazes propagate slowly and then break the glass fibers. When coarse Nonmetals are filled into PP, interfacial debonding and mass microcracks are initiated. A crack is either terminated when it meets another fiber–particulate bundle or branched into finer mass crazing. Interfacial debonding, crack initiation and propagation, and fiber pullout and breakage dissipate tremendous energy. These factors cause improvements in the strength and rigidity of Nonmetal/PP composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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the reuse of Nonmetals recycled from waste printed circuit boards as reinforcing fillers in the polypropylene composites
Journal of Hazardous Materials, 2009Co-Authors: Yanhong Zheng, Zhigang Shen, Yushan XingAbstract:The feasibility of reusing Nonmetals recycled from waste printed circuit boards (PCBs) as reinforcing fillers in the polypropylene (PP) composites is studied by using both mechanical and vicat softening temperature (VST) tests. The concentration of Cu leaded from the composites is also tested. The mechanical test shows that both tensile and flexural properties of the Nonmetals/PP composites can be significantly improved by adding the Nonmetals into PP. The maximum increment of tensile strength, tensile modulus, flexural strength and flexural modulus of the PP composites is 28.4%, 62.9%, 87.8% and 133.0%, respectively. As much as 30 wt% Nonmetals recycled from waste PCBs can be added in the PP composites without violating the environmental regulation. The VST test shows that the presence of Nonmetals can improve the heat resistance of the Nonmetals/PP composites for their potential applications. The optimum particle is the fine or medium Nonmetals recycled from waste PCBs, and the optimum content of the Nonmetals is 30 wt% basing on the comprehensive consideration. All the above results indicate that the reuse of Nonmetals as reinforcing fillers in the PP composites represents a promising way for recycling resources and resolving the environmental pollutions.
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A novel approach to recycling of glass fibers from Nonmetal materials of waste printed circuit boards
Journal of Hazardous Materials, 2009Co-Authors: Yanhong Zheng, Chujiang Cai, Shulin Ma, Xiaohu Zhao, Zhigang Shen, Yushan XingAbstract:The printed circuit boards (PCBs) contain nearly 70% Nonmetal materials, which usually are abandoned as an industrial solid-waste byproduct during the recycling of waste PCBs. However those materials have abundant high-value glass fibers. In this study, a novel fluidized bed process technology for recycling glass fibers from Nonmetal materials of waste PCBs is studied. The recycled glass fibers (RGF) are analyzed by determination of their purity, morphology and surface chemical composition. This process technology is shown to be effective and robust in treating with Nonmetal materials of waste PCBs. The thermoset resins in the Nonmetal materials are decomposed in the temperature range from 400 °C to 600 °C. And the glass fibers are collected at high purity and recovery rate by the cyclone separators without violating the environmental regulation. This novel fluidized bed technology for recycling high-value glass fibers from Nonmetal materials of waste PCBs represents a promising way for recycling resources and resolving the environmental pollutions during recycling of waste PCBs. © 2009 Elsevier B.V. All rights reserved.
Yanhong Zheng - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of polypropylene composites reinforced by Nonmetals recycled from waste printed circuit boards during tensile testing
Journal of Applied Polymer Science, 2009Co-Authors: Yanhong Zheng, Chujiang Cai, Zhigang Shen, Yushan XingAbstract:A great amount of work has been done over the past few years to reuse the Nonmetals recycled from waste printed circuit boards in polypropylene (PP) composites. This is because of the very fast generation rate of Nonmetal pollution in the world each year and the very fast growing rate of PP applications in industries. This work focuses on the dynamic effects of Nonmetals of different particle sizes on the tensile properties and reinforcing mechanisms of Nonmetal/PP composites by in situ scanning electron microscopy tensile testing. The observed results show that the dominant deformation mechanism in pure PP is shear yielding. When fine Nonmetals are filled into PP, mass microcracks are initiated. The glass fibers first resist the cracks and undertake the loading when they propagate. The crazes propagate slowly and then break the glass fibers. When coarse Nonmetals are filled into PP, interfacial debonding and mass microcracks are initiated. A crack is either terminated when it meets another fiber–particulate bundle or branched into finer mass crazing. Interfacial debonding, crack initiation and propagation, and fiber pullout and breakage dissipate tremendous energy. These factors cause improvements in the strength and rigidity of Nonmetal/PP composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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the reuse of Nonmetals recycled from waste printed circuit boards as reinforcing fillers in the polypropylene composites
Journal of Hazardous Materials, 2009Co-Authors: Yanhong Zheng, Zhigang Shen, Yushan XingAbstract:The feasibility of reusing Nonmetals recycled from waste printed circuit boards (PCBs) as reinforcing fillers in the polypropylene (PP) composites is studied by using both mechanical and vicat softening temperature (VST) tests. The concentration of Cu leaded from the composites is also tested. The mechanical test shows that both tensile and flexural properties of the Nonmetals/PP composites can be significantly improved by adding the Nonmetals into PP. The maximum increment of tensile strength, tensile modulus, flexural strength and flexural modulus of the PP composites is 28.4%, 62.9%, 87.8% and 133.0%, respectively. As much as 30 wt% Nonmetals recycled from waste PCBs can be added in the PP composites without violating the environmental regulation. The VST test shows that the presence of Nonmetals can improve the heat resistance of the Nonmetals/PP composites for their potential applications. The optimum particle is the fine or medium Nonmetals recycled from waste PCBs, and the optimum content of the Nonmetals is 30 wt% basing on the comprehensive consideration. All the above results indicate that the reuse of Nonmetals as reinforcing fillers in the PP composites represents a promising way for recycling resources and resolving the environmental pollutions.
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A novel approach to recycling of glass fibers from Nonmetal materials of waste printed circuit boards
Journal of Hazardous Materials, 2009Co-Authors: Yanhong Zheng, Chujiang Cai, Shulin Ma, Xiaohu Zhao, Zhigang Shen, Yushan XingAbstract:The printed circuit boards (PCBs) contain nearly 70% Nonmetal materials, which usually are abandoned as an industrial solid-waste byproduct during the recycling of waste PCBs. However those materials have abundant high-value glass fibers. In this study, a novel fluidized bed process technology for recycling glass fibers from Nonmetal materials of waste PCBs is studied. The recycled glass fibers (RGF) are analyzed by determination of their purity, morphology and surface chemical composition. This process technology is shown to be effective and robust in treating with Nonmetal materials of waste PCBs. The thermoset resins in the Nonmetal materials are decomposed in the temperature range from 400 °C to 600 °C. And the glass fibers are collected at high purity and recovery rate by the cyclone separators without violating the environmental regulation. This novel fluidized bed technology for recycling high-value glass fibers from Nonmetal materials of waste PCBs represents a promising way for recycling resources and resolving the environmental pollutions during recycling of waste PCBs. © 2009 Elsevier B.V. All rights reserved.
Andrew M Rappe - One of the best experts on this subject based on the ideXlab platform.
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chemical pressure driven enhancement of the hydrogen evolving activity of ni2p from Nonmetal surface doping interpreted via machine learning
Journal of the American Chemical Society, 2018Co-Authors: Robert B Wexler, John Mark P Martirez, Andrew M RappeAbstract:The activity of Ni2P catalysts for the hydrogen evolution reaction (HER) is currently limited by strong H adsorption at the Ni3-hollow site. We investigate the effect of surface Nonmetal doping on the HER activity of the Ni3P2 termination of Ni2P(0001), which is stable at modest electrochemical conditions. Using density functional theory (DFT) calculations, we find that both 2p Nonmetals and heavier chalcogens provide nearly thermoneutral H adsorption at moderate surface doping concentrations. We also find, however, that only chalcogen substitution for surface P is exergonic. For intermediate surface concentrations of S, the free energy of H adsorption at the Ni3-hollow site is −0.11 eV, which is significantly more thermoneutral than the undoped surface (−0.45 eV). We use the regularized random forest machine learning algorithm to discover the relative importance of structure and charge descriptors, extracted from the DFT calculations, in determining the HER activity of Ni2P(0001) under different doping c...
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Chemical Pressure-Driven Enhancement of the Hydrogen Evolving Activity of Ni2P from Nonmetal Surface Doping Interpreted via Machine Learning
2018Co-Authors: Robert B. Wexler, John Mark P Martirez, Andrew M RappeAbstract:The activity of Ni2P catalysts for the hydrogen evolution reaction (HER) is currently limited by strong H adsorption at the Ni3-hollow site. We investigate the effect of surface Nonmetal doping on the HER activity of the Ni3P2 termination of Ni2P(0001), which is stable at modest electrochemical conditions. Using density functional theory (DFT) calculations, we find that both 2p Nonmetals and heavier chalcogens provide nearly thermoneutral H adsorption at moderate surface doping concentrations. We also find, however, that only chalcogen substitution for surface P is exergonic. For intermediate surface concentrations of S, the free energy of H adsorption at the Ni3-hollow site is −0.11 eV, which is significantly more thermoneutral than the undoped surface (−0.45 eV). We use the regularized random forest machine learning algorithm to discover the relative importance of structure and charge descriptors, extracted from the DFT calculations, in determining the HER activity of Ni2P(0001) under different doping concentrations. We discover that the Ni–Ni bond length is the most important descriptor of HER activity, which suggests that the Nonmetal dopants induce a chemical pressure-like effect on the Ni3-hollow site, changing its reactivity through compression and expansion
