Controllable Preparation And Application Properties Of Cuprous Oxide Nanomaterials

Cuprous oxide（Cu₂O）is a direct strip line semiconductor material with a narrow band gap.Due to its photoelectric properties,Cu₂O nanomaterials have a wide range of applications in the fields of photocatalysis,solar cells,lithium ion batteries,gas-sensitive materials,etc.In this paper,Cu₂O nanoparticles with stable truncated cube structure were prepared by liquid phase reduction.The systematic study changes the reaction conditions:the time of adding the reducing agent,the concentration of the surfactant,the rate of passing nitrogen,and the effect of the reaction time on the material.The Cu₂O nanomaterial with stable truncated cube structure can be controlled in the size range of 183-747 nm.The performance of the prepared Cu₂O nanomaterials in photoelectric catalytic oxidation of methanol and ultrashort pulse fiber lasers was studied.When Cu₂O is used as a carrier to support a precious metal（Pt）composite catalyst as a catalyst for catalytic oxidation of methanol,it is found that the prepared Pt-based composite catalyst with a size of 400 nm as a carrier of Cu₂O has excellent electrocatalytic oxidation performance of methanol and resistance to CO poisoning,and The catalytic performance and anti-CO poisoning ability under light conditions are relatively improved due to the photocatalytic synergistic effect.Cu₂O nanomaterials are integrated into erbium-doped fiber lasers as saturable absorber materials.By adjusting the pump power,soliton mode locking and harmonic mode locking of the 251 st order are realized,and ultrashort pulse lasers with a stable wavelength of 1 556.8 nm are realized Output.The main conclusions are as follows:（1）Preparation of Cu₂O nanomaterials with stable truncated cube structure by liquid-phase reduction method using ascorbic acid as reducing agent.Study the controllable preparation of Cu₂O nanomaterials by changing the preparation conditions:reducing agent addition time,surfactant PEG400 concentration,O2 content during the reaction,reaction time,etc.The concentration of the surfactant PEG400 affects the size of the nanoparticles and has no significant effect on the morphology as the concentration of the surfactant increases,while the size increases greatly,and there is no significant change in the size when it reaches a certain concentration（0.75 M）.Changing the rate of passing nitrogen during the reaction will affect the rate of the reduction reaction,which will have a significant effect on the size of the nanomaterials.The smaller the rate of passing nitrogen,the larger the size of the nanomaterials.The morphology of the nanomaterials prepared by changing the reaction time did not change,but with the increase of the reaction time,the crystal growth size increased,the reaction time increased by 20 min,and the size of the truncated cube increased by about 100 nm.Through research and changing the experimental preparation conditions,a controllable Cu₂O nanocube material with a truncated cube structure with an average size of 183-747 nm was obtained.（2）Prepare Pt/Cu₂O composite catalyst by photoreduction deposition method and study the effect of photoreduction deposition time and light source power on the electrocatalytic oxidation performance of the composite catalyst.Using a 500 W mercury lamp as the light source for light deposition for 2 hours Oxidized methanol has higher performance.The effect of composite catalysis of Cu₂O with different sizes on the electrocatalytic oxidation performance was studied.It was found that the composite catalyst with a size of 400 nm Cu₂O and Pt catalyzed the oxidation of methanol.The mass activity was 412.6 mA/mg.It reached 65.03%when it was stable,and the If/Ib value was 1.24.Compared with commercial Pt/C catalysts,Pt/Cu₂O catalysts have high catalytic activity and stability,and have strong resistance to carbon monoxide（CO）poisoning.When the oxide semiconductor is used as a carrier,it can adsorb oxygen-containing groups and provide abundant hydroxyl groups to promote methanol oxidation.Under mercury lamp lighting conditions,the peak potential shifted by 11mV negatively,and the peak current increased by 64.9 mA/mg;the value of If/Ib increased by 0.03,and the mass activity decreased to 54.49%after 1150 cycles of cyclic stability testing.Enhanced resistance to CO poisoning.Because semiconductor materials can absorb photo-generated electrons and hole pairs during light exposure,photo-generated electrons are transferred to Pt particles to participate in the catalytic oxidation of methanol,promote the further oxidation of methanol oxidation intermediates,and release more Pt active sites.Photogenic holes have strong oxidizing ability to catalyze methanol oxidation.The decrease in the stability of the catalyst under light conditions may be due to the influence of the light catalyst for a long time during the cycle test.Under the effect of photoelectric cooperative catalysis,the catalytic oxidation performance of the catalyst is improved.（3）The Cu₂O truncated cube nano-materials were deposited on ultra-fine optical fiber by laser-induced light to obtain a saturable absorber device.The nonlinear absorption characteristics of the saturable absorber were measured,and the saturation light intensity and modulation depth of the saturable absorber were found to be 65.8 mW/cm2 and 12.2%,respectively.The Cu₂O saturable absorber is integrated into the Erbium-doped fiber laser.The Erbium-doped fiber laser based on the Cu₂O saturable absorber realizes the traditional soliton mode locking and harmonic mode locking.When the pump power is 219 mW,the traditional soliton mode locking is achieved,the mode locking state is stable,the stable output center wavelength is 1556.8nm,the repetition frequency is 3.91 MHz,the pulse width is 769 fs,and the spectral width is 3.9 nm.In the case of keeping the polarization of the oscillation cavity unchanged,only increasing the pump power can achieve 28,56,80,119 and 251 harmonic mode locking.When the pump power is 335 mW,mode locking up to 251 harmonics is achieved.Based on the Cu₂O saturable absorber,the 251st harmonic mode-locked pulse output with a center wavelength of 1556.8 nm,a repetition frequency of 0.98 GHz,a pulse width of 682 fs,and a spectral width of 4.5 nm was realized for the first time.