title: Conversion of 1T-MoSe2to 2H-MoS2xSe2-2xmesoporous nanospheres for superior sodium storage performance.
abstract: S-Doped 2H-MoSe2(i.e., 2H-MoS2xSe2-2x) mesoporous nanospheres assembled from several-layered nanosheets are synthesized by sulfurizing freshly-prepared 1T-MoSe2nanospheres, and they serve as a robust host material for sodium storage. The sulfuration treatment is found to be beneficial for removing surface/interface insulating organic contaminants and converting the 1T phase to the 2H phase with improved crystallinity and electrical conductivity. These result in significantly enhanced sodium storage performance, including charge/discharge capacity, first Coulombic efficiency, cycling stability, and rate capability. Coupled with benefits from in situ carbon modification and its mesoporous morphology, the 2H-MoS2xSe2-2x(x = 0.22) nanosphere anode can maintain a reversible capacity of 407 mA h g-1after 100 cycles with no observable capacity fading at a high current density of 2.0 A g-1. This value is much higher than those of the anode fabricated with the freshly-prepared 1T-MoSe2(95 mA h g-1) and the annealed 2H-MoSe2(144 mA h g-1) samples. As the current density rises from 0.05 to 5.0 A g-1(100-fold increase), the discharge capacity retention is significantly increased from 39% before sulfuration to 65% after sulfuration. This superior electrochemical performance of the 2H-MoS2xSe2-2xelectrode suggests a promising way to design advanced sodium host materials by surface/interface engineering.
authors.affiliation: School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009, P. R. China. apjunxu@hfut.edu.cn and Center of Super-Diamond and Advanced Films (COSDAF), and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, P. R. China. apcslee@cityu.edu.hk.
authors.forename: Junjun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF), and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, P. R. China. apcslee@cityu.edu.hk and State Key Laboratory of Heavy Oil Processing, and College of Science, China University of Petroleum (East China), Qingdao 266580, P. R. China.
authors.forename: Wenpei
authors.initials: W
authors.lastname: Kang
authors.affiliation: School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009, P. R. China. apjunxu@hfut.edu.cn.
authors.forename: Miao
authors.initials: M
authors.lastname: Jiang
authors.affiliation: School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009, P. R. China. apjunxu@hfut.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: You
authors.affiliation: Physics Laboratory, Industrial Training Center, Shenzhen Polytechnic, Shenzhen 518055, P. R. China.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF), and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, P. R. China. apcslee@cityu.edu.hk.
authors.forename: Tsz-Wai
authors.initials: TW
authors.lastname: Ng
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF), and School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, P. R. China.
authors.forename: Denis Y W
authors.initials: DY
authors.lastname: Yu
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF), and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, P. R. China. apcslee@cityu.edu.hk.
authors.forename: Chun-Sing
authors.identifier: http://orcid.org/0000-0001-6557-453X
authors.initials: CS
authors.lastname: Lee
authors.affiliation: School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009, P. R. China. apjunxu@hfut.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu