22 results on '"Liu, Huiling"'
Search Results
2. Designing heterostructured FeP—CoP for oxygen evolution reaction: Interface engineering to enhance electrocatalytic performance.
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Hou, Shuang, Zhang, Ansai, Zhou, Qi, Wen, Yingjie, Zhang, Sixie, Su, Linfeng, Huang, Xinjie, Wang, Tian, Rui, Kun, Wang, Cheng, Liu, Huiling, Lu, Zhiyi, and He, Peilei
- Subjects
OXYGEN evolution reactions ,METAL-organic frameworks ,DENSITY functional theory ,ENERGY conversion ,POTENTIAL barrier ,HETEROSTRUCTURES - Abstract
It is significant to develop highly efficient electrocatalysts for energy conversion systems. Interface engineering is one of the most feasible approaches to effectively enhance the electrocatalytic activity. Herein, the density functional theory (DFT) calculations predict that the potential barriers of Fe sites at the interface of FeP—CoP heterostructures are lower than that of Fe sites in FeP nanoparticles (NPs), Co sites in CoP NPs, or Co sites in heterostructures. Motivated by the DFT calculation results, FeP—CoP heterostructures have been designed and synthesized by a metal—organic frameworks (MOFs) confined-phosphorization method. The FeP—CoP exhibits the lowest overpotential of 230 mV at the current density of 10 mA·cm
−2 for oxygen evolution reaction (OER), compared with FeP (470 mV) and CoP (340 mV), which outperforms most of transition metal-based catalysts. The Tafel analysis of FeP—CoP heterostructures shows an improved reaction kinetic pathway with the smallest slope of 90.3 mV·dec− 1 , as compared to the Tafel slopes of FeP NPs (137 mV·dec− 1 ) and CoP NPs (114 mV·dec− 1 ). And the FeP—CoP shows extraordinary long-term stability over 24 h. The excellent activity and long-term stability of FeP—CoP derive from the synergistic effect between FeP and CoP. [ABSTRACT FROM AUTHOR]- Published
- 2023
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3. Catalytic activity of Ru‐N4 doped vacancy fullerenes (Ru‐N4‐C54 and Ru‐N4‐C64) for oxygen reduction and CO oxidation: A density functional theory investigation.
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Yang, Siwei, Cheng, Yaxuan, Liu, Huiling, and Huang, Xuri
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DENSITY functional theory ,OXYGEN reduction ,CATALYTIC activity ,FULLERENES ,ACTIVATION energy ,OXIDATION ,CATALYSTS - Abstract
In this work, the catalytic activity of Ru‐N4 doped fullerenes (Ru‐N4‐C54 and Ru‐N4‐C64) for oxygen reduction reaction (ORR) and CO oxidation reaction (COOR) has been systematically investigated from thermodynamics and kinetics by density functional theory (DFT). For ORR, DFT results display that Ru‐N4‐C54 and Ru‐N4‐C64 have satisfactory catalytic behavior both thermodynamically and kinetically. The relative energy curves show that the entire four‐electron process of the most favorable ORR path on Ru‐N4‐C54 and Ru‐N4‐C64 are exothermic, and the activation energies of the rate‐limiting step are 0.60 and 0.40 eV, respectively, which are lower than the calculated value 0.79 eV for Pt (111). For COOR, DFT results reveal that Ru‐N4‐C64 has better catalytic property both thermodynamically and kinetically. The relative energy curve shows that the entire COOR process of the preferred Langmuir–Hinshelwood (LH) mechanism on Ru‐N4‐C64 is exothermic, and the activation energy of the rate‐limiting step is 0.93 eV. Therefore, two hopeful ORR catalysts (Ru‐N4‐C54 and Ru‐N4‐C64) with performance comparable to Pt (111) and one promising COOR catalyst (Ru‐N4‐C64) are identified. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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4. Theoretical study on the structures, isomerization, and stability of [Si, C, N, S] isomers
- Author
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Tao Ting-Ting, Liu Huiling, Yang Yu-Hong, Sun Chiachung, Zhou Zhongjun, and Huang Xuri
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Chemistry ,Ab initio ,Condensed Matter Physics ,Ring (chemistry) ,Kinetic energy ,Biochemistry ,Transition state ,Crystallography ,Computational chemistry ,Potential energy surface ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,Isomerization - Abstract
The structures, energies, spectral parameters, and stabilities of the doublet [Si, C, N, S] radical are explored at the density functional theory and ab initio levels. Eighteen isomers including chainlike, three-membered ring, four-membered ring and cagelike structures are located, connected by 25 interconversion transition states at the B3LYP/6-311G(d) level. The structures of the kinetically stable isomers and their relevant transition states are further optimized at the QCISD/6-311G(2d) level. At the CCSD(T)/6-311 + G(2d)//QCISD/6-311G(2d)+ZPVE level, the global lowest-lying isomer NCSiS 1 is a bent structure. Additionally, the chainlike isomers CNSiS 2 , SiNCS 3 , SiSCN 4 , SiSNC 5 , and SiCNS 6 also process considerable kinetic barriers (more than 10.0 kcal/mol). All the six isomers may be experimentally or astrophysically observable. The bonding natures of all the six isomers are analyzed seriously. The calculated results are compared with those of analogous molecules [Si, Si, N, S], [Si, C, P, S], and [Si, C, N, O]. Implications of the computational structures and spectroscopies are also discussed.
- Published
- 2011
5. Iron-catalyzed olefin synthesis by direct coupling of alkenes with alcohols: A DFT investigation.
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Feng, Wei, Sun, Yanwei, Liu, Huiling, Xu, Kejin, and Huang, Xuri
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ALKENES ,DENSITY functional theory ,ELECTROPHILIC substitution reactions ,ELECTRON spin states ,PROTON transfer reactions - Abstract
Graphical abstract Highlights • Carbocation intermediate was found in the catalytic cycle. • Electrophilic addition step is rate-limiting step. • High-spin state Fe plays an essential role in the catalyzed reaction. • (E)-alkene is the major product. Abstract The mechanism of the iron-catalyzed olefin synthesis reaction was investigated using the density functional theory (DFT) calculations. The catalytic performances of the FeCl 3 and FeCl 2 in different spin states for the olefin synthesis reaction were studied in detail. Both of the two reactions are found to proceed predominantly on high spin state potential energy surfaces, sextet and quintet respectively. The whole catalytic cycle can be divided into three stages: the dehydration step, the electrophilic addition step, and the deprotonation step. The electrophilic addition transition state has the highest energy in the whole catalytic cycle, which is consistent with the experimental prediction. According to the results, (E)-alkene is the main product in both the FeCl 3 and the FeCl 2 catalyzed olefin synthesis reaction. The geometry, mechanism, and the overall reaction barriers of the olefin synthesis reaction are very similar when FeCl 2 and FeCl 3 are used as catalysts. The reaction barrier of FeCl 2 catalyst is lower than that of FeCl 3 , showing that FeCl 2 may be more effective in this kind of olefin synthesis reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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6. Methanol activation catalyzed by Pt7, Pt3Cu4, and Cu7 clusters: A density functional theory investigation.
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Wei, Aiwen, Feng, Wei, Liu, Huiling, Huang, Xuri, and Yang, Guanghui
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METHANOL ,CHEMICAL synthesis ,METHANOL as fuel ,CHEMICAL alcohol synthesis ,DENSITY functional theory ,CHEMICAL reactions - Abstract
Metal clusters were considered as excellent catalysts for methanol dissociation. In this work, two main decomposition mechanisms of methanol on Pt
7 , Pt3 Cu4 , and Cu7 clusters were investigated by the density functional theory. One was methanol direct dehydrogenation, and the other was non‐CO‐involved oxidation. Stable adsorption configurations, elementary reaction barriers, the potential energy surface (PES), and the charge analysis were elucidated. The results showed that on Pt7 cluster, methanol was favorable for direct decomposition. On Pt3 Cu4 and Cu7 clusters, methanol was inclined to the pathway of non‐CO‐involved oxidation. All the transition‐state energies and the final‐state energies were related in a linear, including those for the clusters. The results may be useful for computational design and catalysts optimization. [ABSTRACT FROM AUTHOR]- Published
- 2018
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7. Theoretical investigation on the interaction of hypergolic monomethylhydrazine with 1-chloro-1,1-dinitro-2-( N-chloroamidino)ethane using DFT methods.
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Feng, Wei, Liu, Huiling, Huang, Xuri, Yang, Guanghui, Wei, Aiwen, and Zhang, Dandan
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METHYL hydrazine , *ETHANES , *DENSITY functional theory , *AEROSOLS , *RING formation (Chemistry) - Abstract
The reaction mechanism underlying the hypergolic reaction of pure monomethylhydrazine (MMH) with 1-chloro-1,1-dinitro-2-( N-chloroamidino)ethane (CDNCE) was theoretically investigated with the density functional theory method. We identified two key atomistic level factors that affect ignition delay: (1) exothermicity for the formation of aerosol mCDNCE· nMMH complexes ( m, n = 1, 2). The most cost-effective form was found to be 2CDNCE·MMH with the highest energy release (releasing energy: 23.4 kcal/mol), indicating that the oxidizer-rich form is favorable. These complexes contributed the most to heat gathering and temperature increases in the system at the beginning of all reactions. (2) For the initial reaction of MMH with CDNCE, the S2 mechanism was preferred. The activation barrier of the primary reactions was calculated to be 27.4 kcal/mol, which is also the rate-limiting step of this path. Because the rate of formation of NO was four orders of magnitude lower than the S2 reaction at room temperature, the effect of MMH with NO was less significant at temperatures below 800 K. Thus, we consider the ignition reaction of MMH with CDNCE to be well characterized. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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8. Mechanistic studies on the pH-controllable interconversion between hydrogen and formic acid in water: DFT insights.
- Author
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Zhang, Dandan, Chen, Xiankai, Liu, Huiling, and Huang, Xuri
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HYDROGEN ,FORMIC acid ,DENSITY functional theory ,ORGANOIRIDIUM compounds ,HYDROGEN transfer reactions - Abstract
A complete reaction mechanism for interconversion between hydrogen and formic acid catalyzed by [C,N] cyclometallated organoiridium complex [Ir
III (Cp*)(4-(1H-pyrazol-1-yl-κN2 )benzoic acid-κC3 )(H2 O)]2 ·SO4 , i.e. [Ir-1]2 ·SO4 , has been revealed by density functional theory (DFT) calculations. For both the hydrogen storage catalytic cycle I and hydrogen evolution catalytic cycle II, the detailed reaction profiles with the key transition states and intermediates are revealed. Catalytic cycle I shows that the dihydrogen heterolysis facilitated by OH− gives the considerable stable iridium hydride intermediate M-4, followed by an outer-sphere hydrogen transfer to afford a metal–formate complex M-6. Upon the increasing of pH, catalytic cycle II occurs via the generation of the metal–formate complex M-7, followed by the outer-sphere β-H elimination to form a metal–hydride complex M-9, which is subsequently protonated by the hydrated proton H3 O+ to afford dihydrogen. The decomposition of bicarbonate and the β-hydride elimination of formate are believed to be the rate-determining steps for cycle I and II, respectively. The acid–base equilibrium between the hydroxy and oxyanion form on the catalyst [C,N] ligand has a considerable influence on the catalytic hydrogen transfer. Our studies are in good agreement with experimental results. Remarkably, the new theoretically designed low-cost cobalt(iii) complex, as a promising catalyst, exhibits catalytic activity for the interconversion between hydrogen and formic acid. [ABSTRACT FROM AUTHOR]- Published
- 2015
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9. Theoretical insights into the reaction mechanism and solvation effect of conjugate addition of dimethyl propanedioate to 1-nitroprop-1-ene catalyzed by cinchona alkaloids.
- Author
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Jiang, Haiyang, Zhang, Guobin, Liu, Ying, Guo, Xuying, Liu, Zheng, Yan, Han, Liu, Huiling, and Huang, Xuri
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CONJUGATE addition reactions ,CINCHONA alkaloids ,CATALYTIC activity ,DENSITY functional theory ,QUINUCLIDINES ,TERTIARY amines ,PROTON transfer reactions ,CHARGE transfer kinetics - Abstract
The conjugate addition reaction of dimethyl propanedioate to 1-nitroprop-1-ene catalyzed by cinchona alkaloid derivatives (QD-R″) is investigated using density functional theory calculations in this paper. The geometry optimizations and frequency calculations were carried out at the B3LYP/6-31G( d, p) level, and the accurate energetic parameters were obtained by the B3LYP/6-311++G(2 df,2 p) method. Our calculations find that cinchona alkaloids with -NCONHPh and -NH electron-withdrawing substituents in the quinuclidine show stronger activation on the system than that with -CH electron-donating substituent. The NBO charge analysis for the tertiary amine nitrogen of the quinuclidine affirms that the electron-withdrawing substituents decrease the negative charges on the tertiary amine nitrogen atom, which is favorable for the second proton transfer from the catalyst to α-carbon of 1-nitroprop-1-ene. As a result, the calculations show that the charge distribution of the tertiary amine nitrogen affects the catalytic efficiency of the system. Furthermore, a detailed analysis of the effects of the solvent on the system further revealed the regularity. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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10. The catalytic activity of Pt6M (M = Pt, Ru, Sn) cluster for methanol partial oxidation.
- Author
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Xu, Haixia, Zhang, Min, Chen, Yanyang, Liu, Huiling, Xu, Kejin, and Huang, Xuri
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METHANOL ,DENSITY functional theory ,DEHYDROGENATION ,HYDROGEN atom ,CHEMICAL decomposition ,REACTION mechanisms (Chemistry) - Abstract
Using the density functional theory (B3PW91), we have investigated the reaction mechanism of the initial adsorption and dehydrogenation steps of methanol on Pt 6 M (M = Pt, Ru, Sn) clusters. Pt 6 M (M = Pt, Ru, Sn) clusters are used to simulate the catalysts. Two adsorption and dehydrogenation mechanisms of methanol were studied: one used the hydroxyl-hydrogen atom and methyl-hydrogen atom approach the Pt and M atoms of Pt 6 M, and the other used hydroxyl-oxygen atom and hydroxyl-hydrogen atom attack the M and Pt atoms of Pt 6 M, respectively. The reaction potential energy surfaces (PES) show that on pure Pt 7 cluster the favorable dehydrogenation channel is the decomposition of CH 3 adsorption complex. On the Pt 6 Sn cluster the decomposition of hydroxyl adsorption complex is more favorable. On Pt 6 Ru cluster, both pathways are dominant. The adsorption energy, energy barrier, dissociation energy, NBO analysis and frontier molecular orbital analysis are discussed at B3PW91/LANL2DZ level of theory. The addition of Ru and Sn enhance the catalytic activity of pure Pt for methanol partial oxidation reaction. We may conclude that Pt 6 Ru bimetallic catalyst is most effective among Pt 6 M (M = Pt, Ru, Sn) catalysts for initial adsorption and dehydrogenation reaction of methanol in DMFCs. [ABSTRACT FROM AUTHOR]
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- 2015
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11. Theoretical investigation on the interaction of subnano platinum clusters with graphene using DFT methods.
- Author
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Qi, Qiaofang, Liu, Huiling, Feng, Wei, Tian, Hongwei, Xu, Haixia, and Huang, Xuri
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PLATINUM , *GRAPHENE , *DENSITY functional theory , *NANOWIRES , *MULLIKEN population analysis , *COMPUTATIONAL chemistry - Abstract
The interaction between subnano platinum clusters which are composed of 4–27 atoms with pristine graphene (PG), monovacancy graphene (VG) and Stone–Wales defect graphene (5775) has been investigated using the methods of density functional theory (DFT). According to the similar structures of Pt n clusters and eliminating the disruption of different adsorption styles, the subnano platinum clusters all interact with the substrates through one platinum atom. The calculation results show that the adsorption energy of Pt n clusters interacted with three type substrates are all gradually decreased with the size increasing. The adsorption energies of Pt n adsorbed on VG are increased significantly compared with those adsorbed on PG and 5775. The results have been further demonstrated by the partial density of states (PDOS), spin density distribution, Mulliken population analysis and electron density difference of interfacial Pt and C atoms. The analyses results indicate that the size of Pt n clusters have effects on the interfacial interaction. [ABSTRACT FROM AUTHOR]
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- 2015
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12. Theoretical investigation on mechanism of asymmetric Michael addition of trans-1-nitro-2-phenylethylene to 2-methylpropionaldehyde catalyzed by a Cinchona alkaloid-derived primary amine.
- Author
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Jiang, Haiyang, Zhao, Huanyu, Zhang, Min, Liu, Huiling, and Huang, Xuri
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MICHAEL reaction ,STYRENE ,ADDITION reactions ,BENZOIC acid ,CINCHONA alkaloids ,AMINES ,DENSITY functional theory - Abstract
Using cinchona alkaloid-derived primary amine as catalyst and benzoic acid as co-catalyst, Michael-type addition reactions between enolizable carbonyl compounds and nitroalkenes have been extensively studied; however, our understanding of the mechanism is far from complete. In this paper, a theoretical study is presented for the Michael addition reaction between trans-1-nitro-2-phenylethylene and 2-methylpropionaldehyde catalyzed by 9-epi-QDA and benzoic acid. By performing DFT and ab initio calculations, we have identified a detailed mechanism. The calculations indicated that four continuous steps are involved in the overall reaction: (1) the formation of an iminium intermediate, (2) an addition reaction between the iminium and trans-1-nitro-2-phenylethylene, (3) the proton transfer process, and (4) hydrolysis and regeneration of the catalyst. The rate-determining step is the second proton transfer from the amine group to β-carbon of trans-1-nitro-2-phenylethylene, and the enantioselectivity is also controlled by this step. The calculated results provide a general model that explains the mechanism and enantioselectivity of the title reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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13. Theoretical investigation on the mechanism of FeCl 3 -catalysed cross-coupling reaction of alcohols with alkenes.
- Author
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Sun, Yanwei, Jiang, Haiyang, Tang, Hao, Xu, Haixia, Liu, Huiling, Sun, Kai, and Huang, Xuri
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COUPLING reactions (Chemistry) ,ALCOHOLS (Chemical class) ,ALKENES ,CATALYSIS ,DENSITY functional theory ,INTERMEDIATES (Chemistry) - Abstract
The mechanism of the FeCl3-catalysed cross-coupling reaction of alcohols with alkenes has been investigated using the density functional theory. All calculations were performed in liquid phase. The structures of intermediates and transition states are computed and analysed in detail. The calculations show that the entire catalytic cycle consists in three steps: (1) H-abstraction, (2) free-radical addition, and (3) hydrogen transfer. The rate-limiting step in the whole catalytic cycle is the hydrogen-abstraction step. Only the quartet potential surface is likely to play an essential role in this cross-coupling reaction. The alpha-C(sp3)–H bond of the phenylpropanol is cleaved in a homolytic fashion. Moreover, we justify the change of the oxidation state of iron along the overall reaction pathway on the basis of the computed natural population atomic charges and spin densities. Our calculated results are consistent with and provide a reliable interpretation for the experimental observations that suggest the cross-coupling reaction occurs through a radical mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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14. Theoretical study on mechanism of cinchona alkaloids catalyzed asymmetric conjugate addition of dimethyl malonate to β-nitrostyrene.
- Author
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Jiang, Haiyang, Sun, Yanwei, Liu, Huiling, and Huang, Xuri
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CINCHONA alkaloids ,ETHANES ,DENSITY functional theory ,ENANTIOSELECTIVE catalysis ,REACTION mechanisms (Chemistry) - Abstract
The mechanism and enantioselectivity of the asymmetric conjugate addition of dimethyl malonate to β-nitrostyrene catalyzed by cinchona alkaloid QD-4 as organic catalyst are investigated using density function theory and ab initio methods. Six different reaction pathways, corresponding to the different approach modes of β-nitrostyrene to dimethyl malonate are considered. Calculations indicate that the reaction process through a dual-activation mechanism, in which the tertiary amine of cinchona alkaloid QD-4 first works as a Brønsted base to promote the activation of the dimethyl malonate by deprotonation, and then, the hydroxyl group of QD-4 acts as Brønsted acid to activate the β-nitrostyrene. The rate-determining step is the proton transfer process from the tertiary amine of QD-4 to α-carbon of β-nitrostyrene. The comparison of the mechanisms and energies of the six reaction channels enable us to learn the fact that QD-4 has good catalytic activities for the system, and implies C9OH in QD-4 may not be involved in the activation. These calculation results account well for the observations in experiments. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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15. Bulk trash to nano treasure: Synthesis of two-dimensional brucite nanosheet from high-magnesium nickel slag.
- Author
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Qian, Binbin, Liu, Huiling, Ma, Bing, Wang, Qianqian, Lu, Jun, Hu, Yueyang, Tang, Yuneng, Liu, Cheng, and Dai, Baiqian
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BRUCITE , *NICKEL , *HAZARDOUS wastes , *SOLID waste , *DENSITY functional theory , *HYDROTHERMAL deposits , *WASTE management , *SLAG - Abstract
Fabrication of high-value products from nickel slag, an otherwise solid waste not only enables the sustainable reclamation from hazardous waste but also promotes the nanomaterial multiplex synthesis through a wider range of feedstocks. However, researches on the preparation of two-dimensional nanomaterials from nickel slag are rarely reported. Herein, the synthesis of two-dimensional magnesium hydroxide (2D Mg(OH) 2) nanosheet from a local high-magnesium nickel slag (HMNS) waste is demonstrated, and its subsequent thermal and optical properties were investigated. The (001)-facet-dominance Mg(OH) 2 nanosheet was initially synthesized by leaching, precipitation and hydrothermal treatment with ethanol meditation. Through detailed characterizations and density functional theory (DFT) calculations, the role of ethanol was found to result in the lowest surface energy for the (001) facet of Mg(OH) 2 while restricting the crystal growth on [001]. A final nanosheet structure with an averaged aspect ratio of 14.5 was thus synthesized, as opposed to only 1.6 in the absence of ethanol. The resultant 2D Mg(OH) 2 bears weaker thermal stability and a larger band gap compared with the reference nanoparticles synthesized without ethanol addition. This research contributes a representative example of converting HMNS or any Mg-bearing solid wastes into valuable materials and may open a new avenue to synthesizing 2D materials from low-cost feedstocks. [Display omitted] • Two-dimensional Mg(OH) 2 nanosheets were synthesized from the high-magnesium nickel slag. • Through DFT calculation, the role of ethanol on the directional growth of Mg(OH) 2 has been advanced on the atomic level. • New understandings on the thermal stability and optical property for the facet-dependent Mg(OH) 2 have been offered. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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16. Hollow and Porous N‐Doped Carbon Framework as Lithium‐Sulfur Battery Interlayer for Accelerating Polysulfide Redox Kinetics.
- Author
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Zuo, Xintao, Zhen, Mengmeng, Liu, Dapeng, Fu, Lichao, Qiu, Yanhui, Liu, Huiling, and Zhang, Yu
- Subjects
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LITHIUM sulfur batteries , *DOPING agents (Chemistry) , *OXIDATION-reduction reaction , *ELECTRON density , *DENSITY functional theory , *POROSITY - Abstract
Lithium‐sulfur batteries (LSBs) have become one of the most powerful candidates for next‐generation battery technologies due to their high theoretical energy density and low cost. However, the notorious shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish conversion reaction kinetics cause low sulfur utilization and inferior cycle life. Rational catalyst design on hierarchical pore structures and composition optimization is highly desired to realize synergetic enrichment, accommodation, and catalytic redox capacity of sulfur species. In this consideration, the hollow and porous N‐doped carbon framework is prepared, in which Co nanoparticles (NPs) are evenly embedded (denoted as Co‐HMCF) to modulate electron cloud density of carbons. Electrochemical tests and density functional theory (DFT) calculations demonstrate that Co‐HMCF could simultaneously deliver superior catalytic activity in accelerating LiPSs conversion as well as Li2S nucleation/decomposition to improve overall sulfur redox kinetics. Consequently, the Co‐HMCF interlayer significantly improves the battery performance, including high discharge capacity output (1538 mAh g−1 at 0.2 C), stable long‐term cycle (0.047% capacity decay per cycle for 800 cycles at 1.0 C), and exceptional rate capacity (582 mAh g−1 at 5.0 C). [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
17. Dissociation and oxidation mechanism of methanol on Al12N12 cage: a DFT study.
- Author
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Zhang, Dandan, Feng, Wei, Liu, Huiling, Huang, Xuri, and Yang, Guanghui
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DENSITY functional theory ,DIRECT methanol fuel cells ,DISSOCIATION (Chemistry) ,ADSORPTION (Chemistry) ,FULLERENES ,METHANOL - Abstract
The density functional theory has been used to investigate the methanol adsorption, decomposition and oxidation as well as the water adsorption and decomposition on the clean and Pt-encapsulated Al
12 N12 cages. It is shown that platinum metal atom can be encapsulated within the Al12 N12 cage, thus forming Pt-encapsulated Al12 N12 cage electrocatalyst. According to the reaction results, CH3 OH and H2 O both prefer to be adsorbed on the Al atom top site. The O-H bond scission is the significantly more favorable reaction pathway than C-O bond scission on the cage surface. Furthermore, the structures of the intermediates, transition states and products, the corresponding energy barriers and reaction energies are confirmed. The results also show that the adsorption energies and energy barriers of CH3 OH and H2 O dissociation are cut down slightly with the aid of the platinum atom. Nevertheless, Pt-encapsulated Al12 N12 cage makes the potential energy surface changes smoother than pure Al12 N12 cage. [ABSTRACT FROM AUTHOR]- Published
- 2018
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18. Base-catalyzed hydrolysis of spectinomycin in aqueous solutions: Kinetics and mechanisms.
- Author
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Song, Siqi, Jiang, Mingye, Liu, Huiling, Yao, Jie, Zhang, Xiaoyuan, and Dai, Xiaohu
- Subjects
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HYDROLYSIS , *AQUEOUS solutions , *HYDROLYSIS kinetics , *DENSITY functional theory , *BUFFER solutions - Abstract
Hydrolysis plays an imperative role in the abiotic transformation process of antibiotics in aqueous solutions. However, little information is available on the hydrolysis process of spectinomycin (an aminocyclitol antibiotic). This study systematically investigated the spectinomycin hydrolysis kinetics and mechanisms under different pH via experiments and density functional theory (DFT) computation. Hydrolysis was first conducted in a pure water system under pH of 4.0–9.0 and temperature of 25 °C, 50 °C and 70 °C, respectively. Results showed that hydrolysis was highly dependent on pH and temperature. When pH > 6.0, spectinomycin hydrolysis was accelerated by the catalysis of OH−. Meanwhile, the hydrolysis rate increased with the elevation of temperature. Then, for the reference of the practical environment, the general base-catalyzed hydrolysis and mechanisms were studied under environmental pH 6.0–8.0 and 25 °C. DFT calculation demonstrated that base-catalyzed hydrolysis of spectinomycin could be more thermodynamically and kinetically favorable based on the lower Gibbs free energies of reaction and Gibbs free energies of activation. Further, instead of specific base catalysis (OH−), the general base catalysis (e.g., phosphate buffer) was also found to promote hydrolysis efficiency. The antibacterial activity and ecotoxicities of the hydrolysis product were analyzed to be lower than the precursor, thereby decreasing the environmental impact of spectinomycin. [Display omitted] • Base-catalyzed reaction contributed significantly to hydrolysis at pH > 6.0. • Reaction with OH− was more quickly for spectinomycin as its ΔGb was lower. • DFT combined with TST could predict the spectinomycin k h under pH 6.0–8.0. • Buffer solution could accelerate spectinomycin hydrolysis process. • The effects of hydrolysis product on environment were lower than spectinomycin. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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19. Heteroatom-doped fullerene C70 as non-metal electrocatalysts for oxygen reduction and oxygen evolution from computational study.
- Author
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Yang, Siwei, Cheng, Yaxuan, Liu, Huiling, and Huang, Xuri
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OXYGEN reduction , *OXYGEN evolution reactions , *ELECTROCATALYSTS , *METAL catalysts , *FULLERENES , *HYDROGEN evolution reactions , *PRECIOUS metals , *OVERPOTENTIAL - Abstract
Here, we report on computational oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) efficiencies of a series of heteroatom-doped fullerene C 70 (X(Cn), with B, N, O or Si as dopant X, replacing five different types of carbon atoms (Cn, n = 1–5) on C 70). It is clarified that the X(Cn) is thermodynamically stable. ΔG ⁎OH shows a good linear relationship with ΔG ⁎OOH and ΔG ⁎O. It is worth noting that the ORR overpotential values of N(C1), N(C2), N(C3) and N(C4) are 0.87 V, 0.75 V, 0.67 V and 0.73 V, respectively, which are all greater than Pt (η ORR = 0.45 V), but it shows that ORR can still be catalyzed. Compared with the pristine C 70 , both B and N doping can reduce OER overpotential value and improve OER performance. In particular, N(C4) (η OER = 0.55 V) has the closest overpotential to traditional noble metal OER catalysts such as RuO 2 (η OER = 0.42 V), indicating that it can be used as a potential candidate for OER catalysts. According to the volcano plots, the best ORR and OER activities of X(Cn) appear at ΔG ⁎OH = 0.56 eV and ΔG ⁎O − ΔG ⁎OH = 1.78 eV, respectively. This work can provide some clues for the design and discovery of new non-metal carbon-based electrocatalysts. [Display omitted] • The ORR/OER on X(Cn) (where X is B, N, O or Si; n=1–5, representing the five types of carbon atoms in C 70) is investigated by DFT. • X(Cn) are thermodynamically stable composite materials. • The best ORR (N(C3)) and OER (N(C4)) catalysts show overpotentials of 0.67 and 0.55 V, respectively. • N(C4) shows potential OER activity close to that of traditional noble metal OER catalysts such as RuO 2. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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20. Adsorption behavior and mechanism of acid orange 7 and methylene blue on self-assembled three-dimensional MgAl layered double hydroxide: Experimental and DFT investigation.
- Author
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Pan, Xuemei, Zhang, Miaomiao, Liu, Huiling, Ouyang, Sida, Ding, Nengshui, and Zhang, Ping
- Subjects
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HYDROXIDES , *LAYERED double hydroxides , *METHYLENE blue , *FOURIER transform spectroscopy , *CHEMICAL processes , *SODIUM dodecyl sulfate - Abstract
• The self-assembled 3D MgAl LDH (3D-MA-LDH) were prepared for removing AO7 and MB. • The adsorption capacity of AO7 and MB was 485.6 and 58.3 mg·g−1, respectively. • The adsorption mechanism of AO7 was anion exchange and hydrogen bonding. • The hydrophobic interaction between MB and DS dominated the MB adsorption. • Density functional theory valided the adsorption mechanisms. The removal of toxic ionic dyes is an urgent issue in the water pollution control field. Herein, the self-assembled three-dimensional MgAl layered double hydroxide (3D-MA-LDH) have been synthesized via the soft-template synthesis employing sodium dodecyl sulfate (SDS) as soft template and can be successfully applied in the anionic azo dye Acid Orange 7 (AO7) and cationic heteroaromatic compound methylene blue (MB) removal. The maximum removal capacities were 485.6 and 58.3 mg·g−1 for AO7 and MB, respectively. The removal behavior for AO7 and MB fitted the Langmuir and Freundlich model, respectively, and revealed a diffusion process contained chemical adsorption. X-ray diffraction, Fourier transform spectroscopy, and X-ray photoelectron spectroscopy demonstrated that anion exchange dominated the AO7 removal, while MB was adsorbed via hydrophobic interaction between MB and DS. Density functional theory further confirmed the interaction, wherein the bonding distance was 1.622 Å between AO7 and 3D-MA-LDH's layer. MB showed strong affinity toward DS with no dependence of bond connection to be stably anchored on the 3D-MA-LDH. In addition, the recyclability experiments exibited that 3D-MA-LDH could be stably reused for at least five times. This work provided a new approach for cleaning ionic dyes and broadened the application field of 3D- LDHs. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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21. Enhanced removal of multiple metal ions on S-doped graphene-like carbon-supported layered double oxide: Mechanism and DFT study.
- Author
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Zhang, Lingjie, Ke, Zhisheng, Wang, Wenzhe, Liu, Huiling, Mao, Yuting, Xiang, Mingxue, and Zhang, Ping
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METAL ions , *ADSORPTION capacity , *DENSITY functional theory , *WASTE recycling , *HEAVY metals , *GRAPHENE oxide - Abstract
[Display omitted] • S-doped graphene-like carbon-supported layered double oxide (G/S-LDO) was prepared. • The G/S-LDO showed excellent ability for multiple heavy metal ions (HMIs) removal. • The presence of G/S contributed to enhancement of HMIs removal. • The G/S-LDO retained outstanding adsorption capacity and stability after five cycles. In this study, an innovative sulfur-doped graphene-like carbon-supported layered double oxide (G/S-LDO) was developed for removing toxic heavy metal ions (HMIs; Pb(II), Cd(II), and Co(II)) that are frequently found in wastewater. In single-solute systems, the maximum adsorption capacities were 720.01 (Pb(II)), 473.11 (Cd(II)), and 170.91 (Co(II)) mg/g, which were significantly higher than that of pure LDO and other materials reported in the literature. Even in mixed systems, the outstanding adsorption performance of G/S-LDO toward HMIs was observed with high distribution coefficient values (K d , > 100 L/g). We found that the excellent performance of G/S-LDO depended both on LDO and sulfur-doped graphene-like carbon (G/S) in a complicated manner. In detail, the released OH– from LDO as precipitate agent contributed to HMIs removal. Further, G/S enhanced the 35.42% Pb(II) adsorption, 58.19% for Cd(II) and 48.69% for Co(II) via the complexation and the cation-π interaction from graphene, and coordination and precipitation effect resulting from the doped S. Consistent with experimental results, density functional theory (DFT) calculations unveiled the essence of the enhancement by G/S, and showed that the orbital hybridization between S p and the HMIs p and d states electrons played an important role on HMIs removal. Finally, the recyclability and leaching experimental results suggested the high stability and reusability of G/S-LDO. This work provides new insights into the interactions of HMIs with G/S-based materials, which may facilitate the development of prospective HMIs capturing agents in future studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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22. Computational study on C1- versus C3-regioselectivity in Pd(II)-catalyzed olefination/dearomatization of 2-naphthyl ureas.
- Author
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Chang, Hanwen, Xu, Yongbao, Lv, Lingshan, Liu, Huiling, Wang, Qifeng, and Huang, Xuri
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REGIOSELECTIVITY (Chemistry) , *AROMATIZATION , *NAPHTHYL compounds , *ORGANIC chemistry , *DENSITY functional theory , *ELECTRONIC structure - Abstract
[Display omitted] • A new method of synthesis of an imine derivatives was realized by our group, whose mechanism was studied in this work. • For both reactions, C1-sites are the more reactive sites than C3-sites in C−H cleavages due to electronic effect. • Steric hindrance between naphthyl ring and C2-substituent can make C3-site become the final functionalized site. The regioselectivity in Pd(II)-catalyzed C H direct functionalization of C2-substituted naphthalenes has been a long-term issue in synthetic organic chemistry due to its existence of competitive reaction sites, including C1-, C3- and even C4-sites. Our recent achievement in Pd(II)-catalyzed C1-dearomatization of 2-naphthyl ureas encouraged us to find out the key factors for determining the C1- and C3- regioselectivity of 2-naphthyl ureas based on density functional theory (DFT). In this work, we identified a plausible reaction pathway, which led to the experimental C1-functionalized product with a reasonable energy profile. A homologous pathway giving C3-spirocycle was also calculated to investigate the nature of C1-regioselectivity in this reaction. According to the calculated results, we found that in our reaction C H cleavage was the regioselectivity-determining step, and that C1 was the kinetically favorable site in this step due to electronic effect which makes C1 a more vulnerable site to electrophiles compared to C3, as reflected by the condensed Fukui function and its larger proportion of the highest occupied molecular orbital. Energy decomposition analyses and electronic structure analyses were further performed, which were in good accordance with our conclusion yet indicated C1 was a more sterically hindered site. This result provided us with the inspiration that steric hindrance may play an important role in frequently reported transition metal-catalyzed C3-arylation in the literature. We then selected a recently reported reaction Pd-catalyzed C3-arylation of 2-naphthyl aniline to study the regioselectivity. The result was in line with our assumption that in C3-arylation of 2-naphthyl aniline the preferential functionalization of C3-site is due to its less steric hindrance than C1-site. This work is thus instructive for understanding the regioselectivity in Pd(II)-catalyzed C H direct functionalization of C2-substituted naphthalenes. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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