| Two-dimensional（2D）nanomaterials with unique photoelectric properties have been at the forefront of the research field,being of great significance in various applications such as photoelectronics,spintronics,photocatalysis,chemical and biological sensors,supercapacitors,solar cells and lithium-ion batteries.In terms of photocatalysis,two-dimensional（2D）materials with large surface area can provide more active sites for catalytic reaction,excellent mechanical properties can ensure the continuity of catalysis,and high thermal conductivity is conducive to thermal diffusion in the reaction.It has become an important research object in the fields of photocatalysis,such as photohydrolysis of water to hydrogen and photocatalytic degradation of dyes.In terms of nonlinear optics,two-dimensional（2D）materials have the characteristics of adjustable band gap,short exciton relaxation time and high damage threshold,and have shown great potential as saturable absorbers for laser pulse generation and modulation.Here,we have studied the preparation and optical applications of SnS2,g-C3N4MoxW1-x-x S2,three two-dimensional materials.The research results are as follows:1)We propose a method combining magnetron sputtering and high temperature vulcanization to obtain a large area of 2D SnS2 nanosheets grown vertically on an FTO substrate.The obtained vertical growth of two-dimensional SnS2 films has the largest{001}exposed surface.The photocurrent density of the SnS2⊥FTO photoelectrode reached 10.2 mA/cm2 at 1.5 V（vs.Ag/AgCl）,which is much higher than the reported SnS2 photoelectrode prepared by conventional spin coating.In addition,the device exhibits strong photoresponse from 405 nm to 635 nm,its photocurrent density,photoresponsivity（R）,external quantum efficiency（EQE）,and response rate are several orders of magnitude higher than previously reported.2)Tunable multi-wavelength mode-locked ytterbium-doped fiber laser is realized by using ultrathin graphitic carbon nitride（g-C3N4）nanosheets as saturable absorber.g-C3N4 nanosheets with an average thickness of 3.5 nm are obtained through liquid-phase ultrasonic exfoliation of g-C3N4 powder prepared by high temperature sintering.Passively mode-locked ytterbium-doped fiber laser was obtained by using the g-C3N4 nanosheets coated D-shaped fiber as saturable absorber.Based on a typical balanced twin-detector test system,we investigated the nonlinear saturable absorption property of the as prepared g-C3N4 SA.In the experiment,the g-C3N4 SA exhibited an outstanding nonlinear saturable absorption property.The modulation depth was 36.06%and the saturation intensity was 1.25 GW/cm2 measured by a picosecond laser having a wavelength of 1575 nm.g-C3N4 SA was applied to a passive mode-locked ytterbium-doped fiber laser,and tunable dual-wavelength,three-wavelength and four-wavelength mode-locked pulses were obtained by adjusting the pump power and polarization controller.And the maximum average output power of the mode-locked laser can reach 10.32 mW.The pulse width of the quadruple-wavelength mode-locked laser is 1.9 ns,with a working repetition of 11.2 MHz.This is the first time reporting this tunable multi-wavelength mode-locking phenomenon based on g-C3N4.3)A series of different proportions of molybdenum and tungsten co-doped powder samples(MoxW1-x-x S2)were prepared by hydrothermal method.Then,the corresponding ultrathin 2D ternary Mox W1-xS2 nanosheet suspension was obtained by liquid phase ultrasonic stripping,and finally PVA-MoxW1-xS2 film was prepared.The prepared film is used as a saturable absorber.The erbium-doped fiber laser is used as the research platform to detect the saturation coefficient of the erbium-doped fiber laser,and the femtosecond pulse laser output is obtained. |
PDF Full Text Request