Erjun Kan
Nanjing University of Science and Technology
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Publication
Featured researches published by Erjun Kan.
Journal of the American Chemical Society | 2008
Erjun Kan; Zhenyu Li; Jinlong Yang; Jianguo Hou
Graphene is an important material with potential application in spintronics. Edge-modified zigzag graphene nanoribbons (ZGNR) are investigated with density functional theory. The modifications are realized by saturating the dangling edge bonds by different terminal groups, such as H, NH2, NO2, and CH3. Such modification has a significant impact on the ZGNR electronic structure. Half-metallicity is observed when ZGNR is terminated by NO2 groups at one edge and by CH3 groups on the other side. Free energy analysis suggests that edge-modification is a practical way in experiment to realize half-metallicity.
Applied Physics Letters | 2007
Erjun Kan; Zhenyu Li; Jinlong Yang; J. G. Hou
At B3LYP level of theory, we predict that the half-metallicity in zigzag edge graphene nanoribbon (ZGNR) can be realized when an external electric field is applied across the ribbon. The critical electric field decreases with the increase of the ribbon width to induce the half-metallicity. Both the spin polarization and half-metallicity are removed when the edge state electrons fully transferred from one side to the other under very strong electric field. The electric field range under which ZGNR remains half-metallic increases with the ribbon width. Our study demonstrates a rich field-induced spin polarization behavior, which may lead to some important applications in spinstronics.
Angewandte Chemie | 2016
Shengli Zhang; Meiqiu Xie; Fengyu Li; Zhong Yan; Yafei Li; Erjun Kan; Wei Liu; Zhongfang Chen; Haibo Zeng
Optoelectronic applications require materials both responsive to objective photons and able to transfer carriers, so new two-dimensional (2D) semiconductors with appropriate band gaps and high mobilities are highly desired. A broad range of band gaps and high mobilities of a 2D semiconductor family, composed of monolayer of Group 15 elements (phosphorene, arsenene, antimonene, bismuthene) is presented. The calculated binding energies and phonon band dispersions of 2D Group 15 allotropes exhibit thermodynamic stability. The energy band gaps of 2D semiconducting Group 15 monolayers cover a wide range from 0.36 to 2.62 eV, which are crucial for broadband photoresponse. Significantly, phosphorene, arsenene, and bismuthene possess carrier mobilities as high as several thousand cm(2) V(-1) s(-1) . Combining such broad band gaps and superior carrier mobilities, 2D Group 15 monolayers are promising candidates for nanoelectronics and optoelectronics.
Scientific Reports | 2015
Guangqiang Han; Yun Liu; Lingling Zhang; Erjun Kan; Shaopeng Zhang; Jian Tang; Weihua Tang
New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications.
Journal of Chemical Physics | 2008
Erjun Kan; Xiaojun Wu; Zenyu Li; Xiao Cheng Zeng; Jinlong Yang; J. G. Hou
The established chemical synthetic strategy toward graphene nanoribbons has greatly prompted and justified the research of theoretical designs of novel materials based on graphene. In this paper, we report the novel half-metallicity in C and BN hybrid zigzag nanoribbons even though stand-alone C or BN nanoribbon possesses a finite band gap. By performing first-principles electronic-structure calculations, we find this unexpected half-metallicity in the hybrid nanostructures stems from a competition between the charge and spin polarizations, as well as from the pi orbital hybridization between C and BN. Molecular dynamics simulations indicate that the hybrid nanoribbons are stable. Our results point out a possibility of making spintronic devices solely based on nanoribbons and a new way of fabricating metal-free half metals.
Nano Letters | 2009
Hongjun Xiang; Erjun Kan; Su-Huai Wei; Myung-Hwan Whangbo; Jinlong Yang
It is highly desirable to produce narrow-width graphene nanoribbons (GNRs) with smooth edges in large scale. In an attempt to solve this difficult problem, we examined the hydrogenation of GNRs on the basis of first principles density functional calculations. Our study shows that narrow GNRs can be readily obtained from wide GNRs by partial hydrogenation. The hydrogenation of GNRs starts from the edges of GNRs and proceeds gradually toward the middle of the GNRs so as to maximize the number of carbon-carbon pi-pi bonds, hence effectively leading to narrower GNRs. Furthermore, the partially hydrogenated wide GNRs have similar electronic and magnetic properties as those of the narrow GNRs representing their graphene parts. Therefore, partial hydrogenation of wide GNRs should be a practical and reliable method to produce narrow GNRs in large scale.
Journal of the American Chemical Society | 2012
Erjun Kan; Wei Hu; Chuanyun Xiao; Ruifeng Lu; Kaiming Deng; Jinlong Yang; Haibin Su
The unprecedented applications of two-dimensional (2D) atomic sheets in spintronics are formidably hindered by the lack of ordered spin structures. Here we present first-principles calculations demonstrating that the recently synthesized dimethylmethylene-bridged triphenylamine (DTPA) porous sheet is a ferromagnetic half-metal and that the size of the band gap in the semiconducting channel is roughly 1 eV, which makes the DTPA sheet an ideal candidate for a spin-selective conductor. In addition, the robust half-metallicity of the 2D DTPA sheet under external strain increases the possibility of applications in nanoelectric devices. In view of the most recent experimental progress on controlled synthesis, organic porous sheets pave a practical way to achieve new spintronics.
Physical Review Letters | 2013
Hongjun Xiang; Bing Huang; Erjun Kan; Su-Huai Wei; Xingao Gong
Diamond silicon (Si) is the leading material in the current solar cell market. However, diamond Si is an indirect band gap semiconductor with a large energy difference (2.3 eV) between the direct gap and the indirect gap, which makes it an inefficient absorber of light. In this work, we develop a novel inverse band structure design approach based on the particle swarming optimization algorithm to predict the metastable Si phases with better optical properties than diamond Si. Using our new method, we predict a cubic Si(20) phase with quasidirect gaps of 1.55 eV, which is a promising candidate for making thin-film solar cells.
Nano Letters | 2015
Fang Wu; Chengxi Huang; Haiping Wu; Changhoon Lee; Kaiming Deng; Erjun Kan; Puru Jena
High-temperature ferromagnetic two-dimensional (2D) materials with flat surfaces have been a long-sought goal due to their potential in spintronics applications. Through comprehensive first-principles calculations, we show that the recently synthesized MoN2 monolayer is such a material; it is ferromagnetic with a Curie temperature of nearly 420 K, which is higher than that of any flat 2D magnetic materials studied to date. This novel property, made possible by the electron-deficient nitrogen ions, render transition-metal dinitrides monolayers with unique electronic properties which can be switched from the ferromagnetic metals in MoN2, ZrN2, and TcN2 to half-metallic ones in YN2. Transition-metal dinitrides monolayers may, therefore, serve as good candidates for spintronics devices.
RSC Advances | 2014
Guangqiang Han; Yun Liu; Erjun Kan; Jian Tang; Lingling Zhang; Huanhuan Wang; Weihua Tang
The rational preparation of hierarchical MnO2/polypyrrole (PPy)/reduced graphene oxide (rGO) nanosheets in a sandwich structure is presented. By co-assembly of MnO2/GO and PPy/GO into layer-by-layer architecture and reduction of GO, ternary (MnO2, PPy)/rGO composites were first fabricated. The materials were fully characterized in terms of structure, morphology and electrochemical properties. The unique architecture offers the composites good capacitance by taking advantage of the strong synergistic effect of each component. A maximum specific capacitance as high as 404 F g−1 was obtained for this composite electrode. And over 91% of the initial capacitance was retained after 5000 continuous cycles. The good electrochemical performance and long-term cycling stability make this approach attractive in developing multifunctional hierarchical composites for high-performance supercapacitors.