Study On Preparation,Structure Tuning And Properties Of Nanoporous Copper

Nanoporous metals show broad application prospects in catalysis,sensor,battery and some other fields.Because they exhibit high specific surface area and homogeneous physical and chemical properties due to the combination characterizations of nano size and pore structure.However,Nanoporous noble metals with excellent performance,such as nanoporous Au,nanoporous Pt,nanoporous Ag and so on,are limited by their high cost in wide industrial application.Therefore,it is an urgent problem to seeking the alternative materials with low cost and good performance.Dealloying has become the main preparation method of nanoporous metal because of the simple process and avoiding the disadvantages of traditional template method.A large number of studies have shown that the structure of nanoporous metals can be tuned by adjusting the dealloying process parameters and the design of precursor components.In this thesis,nanoporous copper materials were prepared by the dealloying method,and the preparation,evolution and regulation of precursor alloy and nanoporous structure and functional applications were studied respectively,which laid a technical foundation for the development of low-cost nanoporous materials and pore structure regulation.The main contents include the preparation of nanoporous copper by dealloying method and the study of structure tuning,the effect and mechanism of the third element addition to the precursor on the evolution of the porous structure during dealloying method;the properties of nanoporous structures towards electrocatalysis and degradation applications.The main research works and results are as follows:Part 1.Mn Cu precursor alloy was prepared by single roll spin quenching method,and its dealloying behavior was systematically studied.Nanoporous copper with average pore size ranging from 34 nm to 86 nm and average ligament size ranging from 45 nm to 125 nm can be obtained by adjusting the process parameters such as solution type,applied voltage,concentration,temperature and time in the process of dealloying.Among them,solution concentration,temperature and time have a significant effect on the structure of nanoporous copper.High solution concentration,temperature and long dealloying time are not conducive to the formation of stable structure nanoporous copper.Part 2.Based on the Mn Cu precursor alloy,the effect of minor Ni addition to dealloying precursor will be discussed,and the thermal stability of nano porous copper structure was explored.Due to the good solution ability between Ni and Cu,the Ni addition precursors still maintain uniform single-phase structure.The addition of Ni reduces the surface diffusion coefficient by an order of magnitude,and makes Ni atoms hinder the diffusion and recombination of Cu atoms in the process of dealloying,which effectively reduces the pore size of nanoporous copper.Under the same preparation conditions,the average pore size of nanoporous copper is reduced by 43%by adding 3%Ni element to the precursor.Part 3.On the basis of Mn Cu precursor,the impact of Al addition to the precursor on dealloying behavior was studied.Nanoporous copper with average pore size of 34 nm～84 nm and average ligament size of 50 nm～100 nm can be obtained by adjusting the dealloying time.It is found that the preheating of the precursor helps to expand the size range of the nanoporous structure.Among them,the precursors after heat treatment at 600℃were dealloyed to obtain the composite structure of micropores and nanoparticles.Part 4.The nanoporous coppers were used as electrode materials for non-enzyme glucose sensors.The relationship between peak current density and scanning rate was studied to explore the reaction control procedure.The cyclic voltammetry and chronoamperometry curves were used to study and evaluate the electrocatalytic oxidation of non-enzyme glucose.According to the results of various electrocatalytic properties,Ni addition nanoporous copper showed extraordinary catalytic activity,the detection sensitivity was as high as 1.134 m A·m M·cm^-2,the detection limit was as low as 1.05μm,and it exhibited the good anti-interference and cyclic stability.Its sensitivity is about ten times higher than that of similar catalysts.Part 5.A typical methyl orange azo dye in the printing and dyeing industry was used as the target reactant for the photocatalytic degradation behavior by nanoporous copper catalysts.According to the analysis of the degradation process by UV-vis absorption spectrum,the degradation efficiency of the nanoporous copper catalyst dealloyed by Mn Cu Al precursor is as high as 7.67 mg·g-1·min-1,which is two to three times higher than that of the other two catalysts.The reaction rate constant was evaluated by quasi-first order kinetic formula.The adsorption process of nanoporous copper on methyl orange was investigated by using the intra-particle diffusion model.Various linear relationships show that the adsorption process is not the only diffusion control.According to the degradation behavior at different temperatures,the activation energy of the catalyst was calculated.It turns out to be as low as 18.6 k J·mol^-1 of dealloyed Mn Cu Al,the lower energy value accounts to the better degradation efficiency.