Study On The Growth Mechanism And Application Of Copper Nanostructures Prepared By Solid-state Ionic Method

The solid-state ionic method could be used to prepare metal nanostructures.The method had a simple preparation device.By controlling the direction of the direct current electric field,the current time of application and the magnitude of the current,the direction of growth,length,and order of the nanostructures could be controlled.The price of copper is cheaper than silver and gold,its reserves are abundant,and the copper nanostructures show complementary or higher properties than the corresponding bulk materials in the fields of optics,electricity,magnetism,etc,so it has become a hot spot in current research.In this paper,a solid-state ionic method combined with a vacuum thermal evaporation process was used.RbCu4Cl3I2 was selected as fast ion conductor film,and metal nanostructures were prepared by changing the metal electrodes deposited on both ends of the electrode under the action of an external electric field.The scanning electron microscope and energy scattering spectrometer were used to analyze the morphology and chemical composition of the nanostructures.Based on the above methods,the growth mechanism of the nanostructures prepared by this method could be explored.Besides,under the action of different applied currents,copper films were deposited on both ends of the electrodes,preparing the copper nanostructures with a macroscopic size of centimeters,and the morphology and composition of the copper nanostructures were detected and analyzed.Finally,the surface-enhanced Raman scattering(SERS)characteristics and photoelectric characteristics of copper nanostructures were summarized.When the applied current was 6 μA,the RbCu4Cl3I2 fast ion conductor film and silver/gold electrode were vapor-deposited on the substrate surface,and the copper nanostructures were successfully prepared.The results show that the silver/gold ions in the anode electrode are replaced by copper ions in the fast ion conductor during the preparation of nanostructures,copper ions reach the cathode to be reduced,and then copper nanostructures grow on the edge of the cathode.The composition of the fast ion conductor changes during this process,resulting in the length of the copper nanostructures being less than 1 cm.When the applied current was 4,6,8,10 μA,copper electrodes were vapor-deposited on both ends of the substrate surface,and the copper nanostructures with macroscopic dimensions up to centimeters were prepared.By calculating the fractal dimension of copper nanostructures,the results show that the "dendritic"structure of nanostructures is related to the apical advantage.As the current increases,the fractal dimension also tends to increase,but when the applied current increases to a certain extent,the fractal dimension decreases instead.This should be attributed to the excessive growth rate in the longitudinal direction,leading to a more obvious apical advantage.Analysis of its micro-morphology found that when the applied current was 8 μA,the surface roughness of the copper nanostructures was the highest,and with the increase of the applied current,the orderly arrangement of the micro-morphology of the copper nanostructures increased.Rhodamine 6G(R6G),Rhodamine B(RhB),crystal violet(CV),and malachite green(MG)probe molecules,and copper nanostructures were seleted as the SERS substrates to explore the mechanism of the SERS enhancement.Studies have shown that for the same probe molecule,copper nanostructures prepared under different electric field strengths have different enhancement properties as SERS substrates.When the applied current was 8 μA,the detection sensitivity of copper nanostructures for R6G and CV aqueous solution is better than other currents,and the detection limits are 10-9 mol/L and 10-12 mol/L,respectively.The results show that the high surface roughness makes the copper nanostructures exhibit excellent Raman enhancement characteristics.When the applied direct current were 8,10 μA,the detection limits of the copper-based SERS substrate for RhB and MG molecules are 10-10 mol/L and 10-6 mol/L,respectively.This is due to that the order of arrangement of the copper nanostructure has an enhanced effect on the SERS activity of the substrate.The research results show that increasing the surface roughness and arrangement order of copper nanostructures has a positive effect on the detection limit of probe molecules.Using centimeter-level macroscopic copper nanostructures as conductive materials and combined with the spin coating process,copper nanostructure transparent conductive films were prepared.The optical and electrical properties of the transparent conductive film were characterized by an ultraviolet spectrophotometer and a four-probe tester,and the effects of different electric field strengths and spin coating times on the optical and electrical properties of the conductive film were explored.At the same time,the copper nanostructure transparent conductive film conductivity uniformity was tested.The results show that when the applied current is 10 μA and the number of spin coating is 5 times,the electro-conductive film has the best photoelectric performance.The sheet resistance is 270 Ω/sq,the transmittance reaches 84.2%.And with the increase in the number of spin coatings,the uniformity of the electrical conductivity of the film shows a downward trend.