Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All‐Solid‐State Supercapacitors

Abstract

As the properties of ultrathin two-dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next-generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu2 WS4 can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room-temperature electrical conductivity of hydrogenated-Cu2 WS4 nanosheet film was almost 10(10) times higher than that of pristine bulk sample with a value of about 2.9×10(4) S m(-1) , which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated-Cu2 WS4 is robust and can be retained under high-temperature treatment. The fabricated all-solid-state flexible supercapacitor based on the hydrogenated-Cu2 WS4 nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm(-3) at a current density of 0.31 A cm(-3) . This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.

Recent Advances of Ternary Layered Cu2MX4 (M = Mo, W; X = S, Se) Nanomaterials for Photocatalysis

“…As demonstrated through previous studies, ultrathin Cu 2 WS 4 nanosheets were fabricated by a lithium intercalation exfoliation method and used in flexible all‐solid‐state supercapacitors and electrocatalytic hydrogen evolution . As shown in Figure E, the bulk Cu 2 WS 4 nanosheets were treated by n‐butyllithiun, and the Li‐Cu 2 WS 4 intermediates resulting in a weakened layer interaction of bulk materials.…”

“…E) Illustration of the hydrogenation process, AFM and HRTEM images of Cu 2 WS 4 ultrathin nanosheets. Reproduced with permission . Copyright 2016, Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim.…”

Mixed Metal Sulfides for Electrochemical Energy Storage and Conversion

“…To understand the mechanism of the HER performance enhancement, DFT calculations were performed to verify the experimental results (Figure 11h) [266,267] HSCs: Recently, layered Mo-and W-based ternary sulfides have been assessed as electrode materials for HSCs. [64,268] For example, ultrathin CuWS 4 nanosheets have been explored as electrode materials for all-solid-state flexible HSCs. [268] In order to weaken the interlayer interaction, Li + ions are first intercalated into bulk Cu 2 WS 4 to form Li x Cu 2 WS 4 .…”

“…[64,268] For example, ultrathin CuWS 4 nanosheets have been explored as electrode materials for all-solid-state flexible HSCs. [268] In order to weaken the interlayer interaction, Li + ions are first intercalated into bulk Cu 2 WS 4 to form Li x Cu 2 WS 4 . In the subsequent exfoliation and hydrogen doping processes, hydrogen was incorporated into the exfoliated ultrathin Cu 2 WS 4 nanosheets (Li x Cu 2 WS 4 + H 2 O → H 2 ↑ + LiOH + H y Cu 2 WS 4 ).…”

Unifying miscellaneous performance criteria for a prototype supercapacitor via Co(OH)2 active material and current collector interactions

“…Although has been considerable interest in forming nanostructures of the active material in order to obtain a high specific surface area, which has been found to affect the density of electrochemically active sites (Simon & Gogotsi, ; Lu et al ., ), one other approach to improving performance is to use porous substrates, which, by providing electrolyte channels through the electrode that maximize contract with the active material, can enhance the charge transfer process (Cao et al ., ; Kong et al ., ; Zhang & Lou, ; Bai et al ., ; Xie et al ., ). Moreover, by using a substrate with high conductivity, it may be possible to utilize fast electron transport channels, which facilitate the collection of the electrons (Choi et al ., ; Zhang & Lou, ; Xie et al ., ; Gu et al ., ; Hu et al ., ). From this it can be seen that the effect of the substrate on electrode performance may be considerable, though to date there has been little research into the effect of substrates on modifying the charge transfer and electron transport processes between the electrode and electrolyte.…”