Preparation And Photoelectric Performance Of ReS₂ Nanomaterials

In recent years,as the deepening research of graphene which is a representative of two-dimensional layered nanomaterials,many graphene-like two-dimensional layered materials have attracted extensive attention.ReS₂,the transition metal dichalcogenides?TMDs?,is one of the graphene-like two-dimensional layered materials.Due to the fact that ReS₂ possesses a lot of unique physical and chemical properties which are different from the tranditional TMDs?such MoS₂ and WS₂?,firstly,ReS₂ always displays a direct band gap from bulk to monolayer;secondly,ReS₂ has strong in-plane anisotropy;thirdly,the optical and electrical properties of ReS₂ almost don't change with the increasing of its layers.However,most previous studies on ReS₂ only focused on its mechanical properties and linear optical properties,while there are still some uncertain nonlinear optical properties and photoelectrochemistry properties of ReS₂ waiting to be reveal.Based on this,this paper focuses on the performance and application of ReS₂ in nonlinear optical property and photoelectrochemical,and carries out the following works:?1?Fabrication and transfer of ReS₂ films and nanosheets.We discussed various of preparation and transfer methods of ReS₂ films.First of all,high-quality layered ReS₂ were fabricated by the most convenient mechanical exfoliation method.Secondly,in orde to meet the requirement of ReS₂ area in subsequent experiments,liquid phase exfoliation method combined with vacuum filtration transfer method were used to fabricate ReS₂ films in N-methylpyrrolidone?NMP?solution.Finally,we did some improve by summarizing the deficiencies in the exfoliation experiment:based on the mixed enthalpy theory,the optimal ethanol concentration for exfoliating ReS₂ was found,ReS₂ was greenly and efficiently exfoliated.We obtained ReS₂ films with controllable thickness and area by electrophoretic deposition method.Raman spectra,TEM,AFM,XRD,XPS,and visible absorption spectra were used to study the quality of those ReS₂ films.These works pave the way of subsequent research and application of ReS₂ in nonlinear optics and photoelectrochemistry,and also provide a guide for other nanomaterials in green and efficient preparation.?2?Nonlinear optical properties of ReS₂ films.According to the theoretical basis and laboratory conditions,a set of femtosecond Z-scan measure system was built and then used to characterize the nonlinear optical properties of ReS₂ films with different thickness.The results show that ReS₂ shows obvious thickness dependent saturable absorption property which increases with the increasing of the material thickness.Important nonlinear optical parameters of ReS₂ such as saturable absorption coefficient?_{NL,imaginary part of the third order optical susceptibility}Im??3?and the figure of merit?FOM?were obtained by fitting the experimental data.It provides a theoretical basis for the subsequent application of ReS₂ in the nonlinear optical applications.This part was published together with the fourth part in:Journal of Lightwave Technology?IF:3.652??3?Research of ReS₂ passively Q-switched fiber laser.Based on the saturable absorption property of ReS₂,ReS₂ nanosheets were transferred onto the fiber connector tip to form a saturable absorber,which was used as a Q-switched device to obtain stable output pulses with 1532 nm central wavelength,64 kHz maximum repetition frequency and 38 nJ maximum single-pulse energy in a Q-switched fiber laser at communication band of 1.5?m.This part of work,as the application of ReS₂ in nonlinear optics,provides the experimental basis for the subsequent construction of mode-locked fiber laser.This part was published in an international journal:Optical and Quantum Electronics?IF:1.168?.?4?Research of mode-locked fiber laser based on ReS₂ saturable absorber.Firstly,the ReS₂ saturable absorber was improved by summarizing the Q-switched experiment.Two ReS₂ films were laid up and down a microfiber respectively to form a unique“sandwich”structure in order to increase the interaction of light and matter.Secondly,the saturable absorption property of the ReS₂ saturable absorber were characterized by a home-made typical twin-detector measurement system.Finally,the device was placed in a mode-locked fiber laser at communication band of 1.5?m and obtained stable ultrashort pulses with 1563.3 nm central wavelength and 3.8 ps pulse duration.This part of work provides a new idea for the preparation of other nanomaterials based saturable absorbers.This part was published together with the second part in:Journal of Lightwave Technology?IF:3.652?.?5?Photoelectrochemical properties of ReS₂ films.ReS₂ films were used as photoelectrodes and a 3-electrode photo-electrochemical cell was used as a reactor.Photoelectrochemical properties of ReS₂ films with different thickness were studied and stable and fast photocurrent with sub-second reponse time was obtained.The calculations of electronic band structure,effective mass and the densities of stated of monolayer,2-layer and bulk ReS₂ by first-principle give a theoretical explanation for the photoelectric response.This part of work not only provides experimental basis for the research of ReS₂ photoelectrochemical properties but also lays the foundation for the manufacturing,research and application of photoelectric detectors and other solar energy conversion equipment based on ReS₂.This part was published in:Materials and Design?IF:4.525?.