Phase Engineering,Structural Characterization of 1T-MS2 (M=W-Mo)and their Energy Applications.pdf

1、The two-dimensional layered material is the novel type of materials.The unique layeredstructure features give it excellent physical and chemical properties and broadapplication spectrum.Among these, two-dimensional trans

2、ition metal chalcogenides(TMDs) are particularly prominent.In this thesis, we focused on the design of themetallic phase 1T-MS2 (M =Mo/W), and their related photocatalytic and supercapacitorproperties in detail.The resul

3、ts are expected to be suitable for the future rational designand preparation of high efficiency energy conversion materials to provide new strategyand route.
　　Firstly, we developed a new bottom-up hydrothermal synthe

4、tic strategy tosuccessfully synthesize highly stable 1T-WS2 nanoribbons.Layered tungsten disulfide(WS2) has attracted great attention because of its high potential for electrochemicalenergy applications.However, the semi

5、conducting nature of WS2 with 2H phase largelyhinders its electrochemical performance due to the poor electronic conductivity.In thisstudy, we have successfully synthesized a metallic 1T-WS2 nanoribbon with stableamonia-

6、ion intercalation as a high conductive electrode for high-performancesupercapacitor.The specific capacitance with metallic 1T-WS2 electrode exhibitssignificant enhancement upto the value of 2813 μF/cm2.This value is 12 t

7、imes higheras compare to semiconducting 2H-WS2.Moreover, 1T-WS2 electrode has goodstability even under high current scan, which is ascribed to the stable ammonia-ioninteraction.The correlation between the 1T-WS2 structur

8、e and its electrochemicalperformance has also been discussed.
　　Replacement of expensive noble metals cocatalysts with inexpensive, earth-abundant metallic non-metal materials in most semiconductor-based photocatalyti

9、csystems are highly desirable.Secondly, we demonstrated the fabrication of stable 1T-MoS2 slabs in-situ grown on the CdS nanorods (namely, 1T-MoS2@CdS) usingsolvothermal method.As demonstrated by ultrafast transient abso

10、rption spectroscopy,combined with steady-state and time-resolved photoluminescence, the synergisticeffects from the intimate nanojunction formed between interfaces and the effectiveelectron transport in the metallic phas

11、e 1 T-MoS2 largely contributed to boosting of thephotocatalytic activity for CdS.Notably, the heterostructure with the optimum loadingof 0.2wt％ 1T-MoS2 can exhibit almost 39-fold enhancement than bare CdS.This workrepres

12、ents a step towards the in-situ realization of 1T phase MoS2-based heterostructureas promising cocatalyst with high performance and low cost.
　　In the last part of the dissertation, a layered hetero-structure Ni9S8/Mo

13、S2 hybridwith a tight interface synthesized via hydrothermal method was presented.In contrastto pure materials, the increased surface area and the shorten charge transport pathwayin the layered hybrid significantly promo

14、ted the photocatalytic efficiency of hydrogenevolution reaction (HER), indicating its high potential for catalytic application.Thephotocatalytic tests with Ni9S8-loading varity indicated that the 20 wt％ Ni9S8/MoS2nanohyb

15、rid exhibited the highest photocatalytic activity with HER value of 406 μmolg-1h-1, which is enhanced by 70％ compared to that of as synthesized pure MoS2nanosheets (285.0 μmolg-1 h-1).Moreover, it was 4 times more effici