Mass Production of High‐Quality Transition Metal Dichalcogenides Nanosheets via a Molten Salt Method

Abstract

2D transition metal dichalcogenides (TMDs) are well suited for energy storage and field-effect transistors because of their thickness-dependent chemical and physical properties. However, as current synthetic methods for 2D TMDs cannot integrate both advantages of liquid-phase syntheses (i.e., massive production and homogeneity) and chemical vapor deposition (i.e., high quality and large lateral size), it still remains a great challenge for mass production of high-quality 2D TMDs. Here, a molten salt method to massively synthesize various high-crystalline TMDs nanosheets (MoS 2 , WS 2 , MoSe 2 , and WSe 2 ) with the thicknesses less than 5 nm is reported, with the production yield over 68% with the reaction time of only several minutes. Additionally, the thickness and size of the as-synthesized nanosheets can be readily controlled through adjusting reaction time and temperature. The assynthesized MoSe 2 nanosheets exhibit good electrochemical performance as pseudocapacitive materials. It is further anticipates that this work will provide a promising strategy for rapid mass production of high-quality nonoxides nanosheets for energy-related applications and beyond.

Recent Advances of Two‐Dimensional Nanomaterials for Electrochemical Capacitors

“…Zhou et al. reported an effective MSM to extensively synthesize highly crystalline TMDC nanosheets with thicknesses of less than 5 nm, including MoS 2 , WS 2 , MoSe 2 , and WSe 2 , as shown in Figure . In particular, the production yield of MoS 2 nanosheets could reach about 80 % with increasing reaction time.…”

“…For instance, Zhou et al. assembled ASCs based on MoSe 2 nanosheets and V−MnO 2 electrodes with an increased voltage window of 2.0 V, exhibiting a high energy density of 35.0 Wh kg −1 and good capacitance retention of 85.6 %, even after 5000 cycles. Kou et al.…”

“…Therefore, developing ASCs is as ignificant strategy for high-performance energy-storaged evices. For instance, Zhou et al assembled ASCs based on MoSe 2 nanosheetsa nd VÀMnO 2 [62] electrodes with an increased voltage window of 2.0 V, exhibiting ah igh energy density of 35.0 Wh kg À1 and good capacitance retention of 85.6 %, even after 5000 cycles. Kou et al fabricated CC@NiCo 2 Al LDH/CC@ZIF-8-based ASCs (CC = carbon cloth),g iving rise to ar emarkable energy density of 44 Wh kg À1 at ap ower density of 462 Wkg À1 ,t ogether with remarkable cyclic stability,w ith 91.2 %c apacitance retention over 15 000 charge-discharge cycles (Figure 14).…”

“…b) Yield of MoS 2 underd ifferentr eaction times at 600 8C. c) SEM and d) HRTEMi mage of the edgeofM oS 2 ,e)SEM and f) HRTEM image of the edge of WS 2 ,g )SEM and h) HRTEMimage of the edge of MoSe 2 ,a nd i) SEM and and j) HRTEM image of the edge of WSe 2 .Reproduced with permission [62]. Copyright2 019, Wiley-VCH.…”

Oxygen‐Deficient Homo‐Interface toward Exciting Boost of Pseudocapacitance

“…The energy density of SCs based on double‐layer capacitance, however, is very low as compared with that of batteries 5–7. In recent years, the development of pseudocapacitive materials that enable redox reactions at or near the material surface brings the hope to increase the energy density of SCs to the battery level 8–12. However, most of the pseudocapacitive materials (such as MnO 2 , SnO 2 , and Fe 2 O 3 ) possess sluggish ion diffusion and electron transport, which result in low bulk utilization for charge storage and limited gain in energy density for these pseudocapacitors 9,13,14.…”