Intercalation and Hybridization of Low--Dimensional Nanostructures for Chemical and Physical Study.pdf

1、Two-dimensional (2D) layered transition metal dichalcogenides (TMDCs) and transition metal oxides have unique chemical and physical properties for useful spintronic and electrochemical potential applications.It is highly

2、 desirable to modulate TMDC's structures and compositions for realizing the tunable physical and chemical properties for many specific applications.In this dissertation,multifunctional and high quality TMDCs and transiti

3、on metal oxides related nanomaterials are synthesized,functionalized and intercalated.Subsequently,the chemical and physical properties of the obtained low-dimensional nanomaterials are investigated in detail,along with

4、their potential exploration in the field of the supercapacitors.We are hopeful that these results will be useful for the production of low-cost materials for supercapacitor and spintronic devices.
　　(1)Transition meta

5、l oxides are widely studied in recent years in the field of electrochemical energy storage due to their high specific capacitance,abundant resource and low cost.Here,we synthesized the CuFe2O4-Fe2O3 hybrid nanomaterial f

6、or highly efficient supercapacitor electrode by using eco-friendly low-temperature coprecipitation method.The composite CuFe2O4-Fe2O3 demonstrated the excellent specific capacitance of 638.24 F/g and long cyclic stabilit

7、y up to 2000 charge/discharge cycles.Particularly,the calculated specific capacitance value is 16 times higher than that of pure CuFe2O4.All characterizations and analysis revealed the superior performance of CuFe2O4-Fe2

8、O3 composite as supercapacitor electrode with excellent capacitance retention in comparison to CuFe2O4.The enhanced electrochemical performance of CuFe2O4-Fe2O3 composite can be attributed to the synergistic effect which

9、 is responsible for redox coupling between Cu2+ and Fe3+ that has never been achieved by single component before.
　　(2)Hafnium diselenide (HfSe2) is a 2D layered crystal with various unique physical properties.In this

10、 study,we synthesized high-quality HfSe2 and Cu-intercalated HfSe2 single crystals via chemical vapor transport (CVT) technique.Various characterizations were performed to confirm the structures of the growth samples.The

11、 synthesized materials were also contrastively evaluated as supercapacitor electrode for the possible application of energy storage devices.The calculated specific capacitance values are 27.24 and 141.83 F/g at the scan

12、rate of 10 mV/s for HfSe2 and Cu intercalated HfSe2,respectively.Moreover, due to the unique microstructure of 2D materials,the electrodes also showed a high value of specific capacitance, excellent cycling stability and

13、 energy density.
　　(3)Tantalum diselenide (TaSe2) is a unique layered TMDCs with interesting phenomena such as charge-density wave and superconductivity.Herein, we synthesized high-quality TaSe2 layered single crystal

14、s by an improved CVT technique,and also intercalated it with copper (Cu) to alter its magnetic properties.The ferromagnetism was clearly observed in TaSe2 and Cu-intercalated TaSe2 layered single crystals,which was also

15、supported by first principle DFT calculations.With the intercalation of Cu in TaSe2,the saturation magnetization (Ms) values were found to increase from 0.0035 emu/g to 0.0056 emu/g at 300 K and from 0.0169 emu/g to 0.15

16、54 emu/g at 10 K,illustrating approximately nine times increase in contrast to the pristine TaSe2.Moreover, our DFT calculations further validated the existence of the room temperature ferromagnetism in TaSe2,which becam

17、e more stable after Cu-intercalation due to the increased spin-orbit interaction of Cu atoms compared to Ta atoms.These results affirm the enhancement of ferromagnetism after Cu intercalation in TaSe2 crystals,which may