Strong charge transfer at 2H-1T phase boundary of MoS₂ for superb high-performance energy storage

• Main Authors: Ke, Qingqing, Zhang, Xiao, Zang, Wenjie, Elshahawy, Abdelnaby M., Hu, Yating, He, Qiyuan, Pennycook, Stephen J., Cai, Yongqing, Wang, John
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Materials; Charge Transfer; Graphene
• Online Access: https://hdl.handle.net/10356/150842
• Institution: Nanyang Technological University

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.