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Simple Te-Thermal Converting 2H to 1T@2H MoS2 Homojunctions with Enhanced Supercapacitor Performance

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journal contribution
posted on 30.10.2019, 12:37 by Weihao Li, Yongli Shen, Xiong Xiao, Cuihua An, Guijuan Wei, Yaqian Wang, Jiayang Wang, Yue Wu, Changhua An
Recently, the formation of homojunctions of transition-metal dichalcogenides between the semiconducting 2H phase and semimetal or metallic 1T phase is an effective way to achieve high performance. However, the achievement of the homojunctions usually requires laborious steps, time-consuming steps, and high-cost feedstocks, which results in uncertainties in giving detailed insights into the understanding electron transfer behavior, enhanced performance, and large-scale production. In this work, 1T@2H MoS2 homojunctions have been easily fabricated by a simple Te thermal treatment of 2H-MoS2 nanosheets in H2/Ar atmosphere. The incorporation of Te atoms into the MoS2 lattices leads to the expansion of the MoS2 interlayers, facilitating their charge transport and ion diffusion. As a result, the obtained Te-doped 1T@2H MoS2 homojunction electrode exhibited high conductivity, high specific capacitance of 1053.8 F g–1 in KOH electrolyte at 1 A g–1, excellent rate performance, and outstanding cycling stability. Furthermore, it is interesting that the specific capacitance was continuously increased and reached 2247.6 F g–1 after 10000 cycles due to the continued transformation of residual 2H of the 1T phase during the electrochemical tests. Density functional theory was used to investigate the variations of Hirshfield charge of Mo atoms with the Te-doped and 1T content in the Te-doped 1T@2H MoS2 homojunction, revealing their distinct intrinsic electron capacity at different states. The present work opens a pathway to easily tune the phase engineering of transition-metal dichalcogenides and achieve homojunctions. We expect that the present method can be applied to achieve other phase homojunctions with promising applications in energy storage and conversion.