Strong Charge Transfer at 2H–1T Phase Boundary of MoS2 for Superb High‐Performance Energy Storage

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-05, Vol.15 (21), p.e1900131-n/a
• Main Authors: Ke, Qingqing, Zhang, Xiao, Zang, Wenjie, Elshahawy, Abdelnaby M., Hu, Yating, He, Qiyuan, Pennycook, Stephen J., Cai, Yongqing, Wang, John
• Format: Article
• Language: English
• Subjects: Chalcogenides; Charge distribution; Charge transfer; Displacements (lattice); Energy storage; Graphene; Gravimetry; Molybdenum disulfide; MoS2; Nanotechnology; Phase boundaries; phase boundary; Phase composition; supercapacitors; Transition metal compounds; Two dimensional materials
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201900131

Transition metal dichalcogenides exhibit several different phases (e.g., semiconducting 2H, metallic 1T, 1T′) arising from the collective and sluggish atomic displacements rooted in the charge‐lattice interaction. The coexistence of multiphase in a single sheet enables ubiquitous heterophase and inhomogeneous charge distribution. Herein, by combining the first‐principles calculations and experimental investigations, a strong charge transfer ability at the heterophase boundary of molybdenum disulfide (MoS2) assembled together with graphene is reported. By modulating the phase composition in MoS2, the performance of the nanohybrid for energy storage can be modulated, whereby remarkable gravimetric and volumetric capacitances of 272 F g−1 and 685 F cm−3 are demonstrated. As a proof of concept for energy application, a flexible solid‐state asymmetric supercapacitor is constructed with the MoS2‐graphene heterolayers, which shows superb energy and power densities (46.3 mWh cm−3 and 3.013 W cm−3, respectively). The present work demonstrates a new pathway for efficient charge flow and application in energy storage by engineering the phase boundary and interface in 2D materials of transition metal dichalcogenides. A strong charge transfer ability at the phase boundary of MoS2 is demonstrated. Through modulating the phase composition of MoS2 contacted with graphene, a promoted supercapacitive performance is achieved in MoS2/graphene nanohybrid films. The strategy detailed in the present study reveals that heterophase engineering could be a promising avenue to develop an efficient energy storage device.