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Dive into the research topics where Xuan-zhang Wang is active.

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Featured researches published by Xuan-zhang Wang.


ACS Applied Materials & Interfaces | 2013

Silicon-Doped Graphene: An Effective and Metal-Free Catalyst for NO Reduction to N2O?

Ying Chen; Yue-jie Liu; Hong-xia Wang; Jingxiang Zhao; Qinghai Cai; Xuan-zhang Wang; Yi-hong Ding

Density functional theory (DFT) calculations were performed on the NO reduction on the silicon (Si)-doped graphene. The results showed that monomeric NO dissociation is subject to a high barrier and large endothermicity and thus is unlikely to occur. In contrast, it was found that NO can easily be converted into N2O through a dimer mechanism. In this process, a two-step mechanism was identified: (i) the coupling of two NO molecules into a (NO)2 dimer, followed by (ii) the dissociation of (NO)2 dimer into N2O + O(ad). In the energetically most favorable pathway, the trans-(NO)2 dimer was shown to be a necessary intermediate with a total energy barrier of 0.464 eV. The catalytic reactivity of Si-doped graphene to NO reduction was interpreted on the basis of the projected density of states and charge transfer.


Journal of Molecular Graphics & Modelling | 2013

Can Si-doped graphene activate or dissociate O2 molecule?

Ying Chen; Xiao-chun Yang; Yue-jie Liu; Jingxiang Zhao; Qinghai Cai; Xuan-zhang Wang

Recently, the adsorption and dissociation of oxygen molecule on a metal-free catalyst has attracted considerable attention due to the fundamental and industrial importance. In the present work, we have investigated the adsorption and dissociation of O(2) molecule on pristine and silicon-doped graphene, using density functional theory calculations. We found that O(2) is firstly adsorbed on Si-doped graphene by [2+1] or [2+2] cycloaddition, with adsorption energies of -1.439 and -0.856eV, respectively. Following this, the molecularly adsorbed O(2) can be dissociated in different pathways. In the most favorable reaction path, the dissociation barrier of adsorbed O(2) is significantly reduced from 3.180 to 0.206eV due to the doping of silicon into graphene. Our results may be useful to further develop effective metal-free catalysts for the oxygen reduction reactions (ORRs), thus greatly widening the potential applications of graphene.


Journal of Physical Chemistry A | 2011

Doping of calcium in C(60) fullerene for enhancing CO(2) capture and N(2)O transformation: a theoretical study.

Bo Gao; Jingxiang Zhao; Qinghai Cai; Xiaoguang Wang; Xuan-zhang Wang

Recently, capturing or transforming greenhouse gases, such as CO(2) and N(2)O, have attracted considerable interest from the perspective of environmental protection. In the present work, by studying CO(2) and N(2)O adsorption on pristine and calcium (Ca)-decorated fullerenes (C(60)) with density functional theory (DFT) methods, we have evaluated the potential application of this C(60)-based complex for the capture of CO(2) and transformation of N(2)O. The results indicate that the adsorptions of CO(2) and N(2)O molecules on the pristine C(60) are considerably weak accompanied by neglectable charge transfer. When C(60) is decorated with Ca atoms, however, it is found that CO(2) and N(2)O adsorptions on the C(60) are greatly enhanced. Up to five CO(2) molecules can be adsorbed on the CaC(60) system due to the electrostatic interaction. For N(2)O molecule, it is first molecularly adsorbed on the Ca atom with the adsorption energy of -0.534 eV, followed by the N(2) formation with a low barrier and high exothermicity. Moreover, when four Ca atoms are decorated on the surface of C(60), the maximum number of the adsorbed CO(2) molecules is 16. Our results might be useful not only to widen the potential applications of fullerene but also to provide an effective method to capture or transform greenhouse gases.


Nanotechnology | 2007

Growth of novel ZnO nanohelices modified by SiO2-sheathed ZnO discs

Huijun Gao; Xitian Zhang; M Y Zhou; Zhaohan Zhang; Xuan-zhang Wang

Disc-modified nanohelices (DNHs) of ZnO were synthesized by thermal evaporation. The ZnO DNHs are constructed by nanowires which are regularly attached with discs. The axis of the DNH structure is along the ZnO[0001] direction. The pitch distance, the mean diameter, and the thickness of the nanowires are uniform for each ZnO DNH. Within one period there are 12 discs symmetrically attached on the surfaces of the nanowires. The discs are composed of nanometre-sized ZnO crystal cores and amorphous SiO2 shells. The mechanism of formation of the nanostructures is also discussed.


RSC Advances | 2013

Catalyst-free achieving of controllable carbon doping of boron nitride nanosheets by CO molecules: a theoretical prediction

Jingxiang Zhao; Hong-xia Wang; Yue-jie Liu; Qinghai Cai; Xuan-zhang Wang

Controllable carbon (C) doping in a boron nitride (BN) nanostructure can render it exciting magnetic and conductive properties, which would be very valuable for its potential applications in optoelectronics and spintronics. Thus, searching for an efficient method to achieve C-doped BN nanostructure is of vital importance. Here, using density functional theory (DFT) calculations, we propose a mechanism to obtain C-doping of BN nanosheet by the interactions of two CO molecules with three kinds of defective BN nanosheets, including B or N vacancy and BN divacancy. The results show that the proposed mechanism in the present work has the following advantages: (i) the activation energies are only 0.30 and 0.37 eV for BN sheet with B and N vacancy, respectively, suggesting that this reaction can easily occur. For BN sheet divacancy configuration, because the released energy of CO-coadsorption (−5.49 eV) can completely offset the subsequent barrier (1.72 eV), C-doped BN nanosheet can also be achieved using BN nanosheet with divacancy as a reactant. (ii) No catalyst is needed, thus no extra step is needed to remove the catalyst. (3) The harmful CO molecule can be used as a reactant and transformed into CO2 or O2 molecule. (4) The selectivity of CO for vacancy defect sites is high. The present results provide an effective theoretical method to synthesize C-doped BN nanosheets, which would be useful for the development of BN nanosheet-based devices.


RSC Advances | 2015

One-pot synthesis of hierarchical SnO2 hollow nanospindles self-assembled from nanorods and their lithium storage properties

Qingjiang Yu; Wenqi Wang; Huixin Wang; Y.J. Huang; Jinzhong Wang; Shiyong Gao; Fengyun Guo; Xitian Zhang; Hong Gao; Xuan-zhang Wang; Cuiling Yu

Novel hierarchical SnO2 hollow nanospindles self-assembled from nanorods have been successfully synthesized via a templating approach under hydrothermal conditions. The influence of the reactant concentration on SnO2 products is investigated in detail. It is found that the interplay of the acidic etching of Fe2O3 templates and controlled hydrolysis of SnCl2 is significant for the formation of the hierarchical SnO2 hollow nanostructures. The evolution process and formation mechanism of the hollow structures with nanorods are analyzed from the angle of nucleation and morphology. Moreover, the electrochemical properties of the hollow structures are also studied by charge–discharge cycling, the result displays that the hierarchical SnO2 hollow nanostructure exhibits much better lithium storage properties with higher reversible capacities and enhanced cyclic capacity retention than the commercial SnO2 nanoparticles.


Journal of Nanoparticle Research | 2012

Theoretical insights into the effects of the diameter and helicity on the adsorption of formic acid on silicon carbide nanotube

Ying Chen; Hong-xia Wang; Jingxiang Zhao; Xiaoguang Wang; Qinghai Cai; Yi-hong Ding; Xuan-zhang Wang

The anchoring of small organic molecules onto the semiconductor surface has a great application for developing various molecular devices, such as novel solar cells, fuel cells, hybrid systems, sensors, and so on. In the present work, by carrying out detailed density-functional theory calculations, we have investigated the adsorption of the formic acid (HCOOH) molecule on planar and various curved silicon carbide (SiC) nanotubes. By considering both the molecular and dissociative adsorptions of HCOOH on these SiC nanomaterials, we found that the HCOOH molecule prefers to dissociate into HCOO and H group. Interestingly, different adsorption modes were found for HCOOH on SiC nanotubes, i.e. dissociative monodentate or bidentate adsorption, which depends on the tube diameter and helicity. For (n, 0) SiC nanotube, the monodentate adsorption mode is energetically favorable when n is less than 10. However, HCOOH prefers to be adsorbed on other (n, 0) SiC nanotubes in a bridged bidentate mode, which is similar to those of on (n, n) SiC nanotubes or planar SiC sheet. Moreover, upon HCOOH adsorption, these SiC nanomaterials remain to be of the semiconducting nature and their band gaps are decreased to different degrees. In addition, we also explored the effects of HCOOH coverage on its adsorption on SiC nanotube.


Journal of Nanoparticle Research | 2015

High stability and reactivity of defective graphene-supported FenPt13−n (n = 1, 2, and 3) nanoparticles for oxygen reduction reaction: a theoretical study

Duo Xu; Yu Tian; Jingxiang Zhao; Xuan-zhang Wang

Recent experimental studies have shown that the FePt nanoparticles (NPs) assembled on graphene exhibit enhanced durability and catalytic activity for oxygen reduction reaction (ORR) than Pt—only catalysts. In this work, we have performed density functional theory calculations to investigate the stability and reactivity of several FenPt13−n NPs deposited on defective graphene for ORR, where n is adopted as 0, 1, 2, and 3, respectively. The results indicate that the alloying between Fe and Pt can enhance the stability of NPs and promote their oxygen reduction activity. Moreover, the monovacancy site in the graphene can provide anchoring sites for these bimetallic NPs by forming strong metal–substrate interaction, ensuring their high stability. Importantly, the O2 adsorption on these composites is weakened in various ways, which is ascribed to the change in their averaged d-band center. Thus, these composites exhibit superior catalytic performance in ORR by providing a balance in the O2 binding strength that allows for enhanced turnover. Our results may be useful to unravel the high stability and reactivity of defective graphene-FePt NPs for ORR from a theoretical perspective.


Journal of Molecular Modeling | 2012

Can trans-polyacetylene be formed on single-walled carbon-doped boron nitride nanotubes?

Ying Chen; Hong-xia Wang; Jingxiang Zhao; Qinghai Cai; Xiaoguang Wang; Xuan-zhang Wang

Recently, the grafting of polymer chains onto nanotubes has attracted increasing attention as it can potentially be used to enhance the solubility of nanotubes and in the development of novel nanotube-based devices. In this article, based on density functional theory (DFT) calculations, we report the formation of trans-polyacetylene on single-walled carbon-doped boron nitride nanotubes (BNNTs) through their adsorption of a series of C2H2 molecules. The results show that, rather than through [2 + 2] cycloaddition, an individualmolecule would preferentially attach to a carbon-doped BNNT via “carbon attack” (i.e., a carbon in the C2H2 attacks a site on the BNNT). The adsorption energy gradually decreases with increasing tube diameter. The free radical of the carbon-doped BNNT is almost completely transferred to the carbon atom at the end of the adsorbed C2H2 molecule. When another C2H2 molecule approaches the carbon-doped BNNT, it is most energetically favorable for this C2H2 molecule to be adsorbed at the end of the previously adsorbed C2H2 molecule, and so on with extra C2H2 molecules, leading to the formation of polyacetylene on the nanotube. The spin of the whole system is always localized at the tip of the polyacetylene formed, which initiates the adsorption of the incoming species. The present results imply that carbon-doped BNNT is an effective “metal-free” initiator for the formation of polyacetylene.


Applied Surface Science | 2013

Phosphorus-doped graphene and (8, 0) carbon nanotube: Structural, electronic, magnetic properties, and chemical reactivity

Hong-xia Wang; Ying Chen; Yue-jie Liu; Jingxiang Zhao; Qinghai Cai; Xuan-zhang Wang

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Jingxiang Zhao

Harbin Normal University

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Qinghai Cai

Harbin Normal University

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Xiaoguang Wang

Harbin Normal University

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Hong-xia Wang

Harbin Normal University

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Yue-jie Liu

Harbin Normal University

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Ying Chen

Harbin Normal University

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Bo Gao

Harbin Normal University

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Duo Xu

Harbin Normal University

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Hong Gao

Harbin Normal University

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