论文总字数：28356字

摘 要

脱合金法是制备具有纳米多孔结构功能金属的常用方法。本文研究了Ag₃₀Zn₇₀前驱体合金在含聚乙烯吡咯烷酮（PVP）的HCl溶液中的选择溶解过程，选择适当电压对Ag₃₀Zn₇₀进行电化学脱合金从而制备纳米多孔银（NPS），并对脱合金产物进行XRD、SEM和EDS表征，最终通过循环伏安法研究NPS在含甲醛的碱性溶液中的电流响应特征，探究线性有机大分子PVP的引入量、脱合金时间和电压对NPS的形成过程的影响及其甲醛检测性能。

本实验利用高频感应熔炼及快速凝固方法制备Ag₃₀Zn₇₀前驱体合金条带，XRD结果显示前驱体合金为含有ε相的单相合金。在含有1.0 g/L PVP的0.1 M HCl溶液中对前驱体合金进行恒电位电化学脱合金，获得特征孔径为136~240 nm的NPS。结果显示：随着脱合金时间的延长，Ag₃₀Zn₇₀合金的ε相逐渐转化为NPS；长时间的脱合金过程造成纳米多孔结构韧带粗化，孔隙尺寸增大；随着施加电压的增大，脱合金过程显著加快，且易发生孔结构粗化现象，形成孔径增大，尺寸不均匀的纳米多孔结构，甚至导致多孔结构完全崩塌生成大颗粒状金属物。Ag₃₀Zn₇₀合金在含有不同PVP浓度的0.1 M HCl溶液中的极化曲线表明PVP有机分子抑制阳极溶解反应，优化纳米多孔结构。在1.0 g/L PVP 0.1 M HCl溶液中，Ag₃₀Zn₇₀合金0.20 V电压下脱合金6 ks制得的NPS具有最优纳米多孔结构。在含有不同浓度甲醛的0.1 M KOH溶液中循环伏安结果显示，甲醛氧化电流密度随着浓度的增加而增大。线性拟合HCHO氧化电流密度峰值与HCHO浓度，可得到反应灵敏度为0.28，线性相关系数R可达到0.99，表明在10~100 mM浓度范围内，NPS对甲醛有着优异的检测性能。

关键词：纳米多孔银 电化学脱合金法 聚乙烯吡咯烷酮添加 甲醛检测 循环伏安法

Abstract

Dealloying is a common method to fabricate functional metals with nanoporous structure. In this paper, the selective dissolution process of Ag₃₀Zn₇₀ alloy in HCl solution containing polyvinylpyrrolidone (PVP) has been investigated. Under the proper applied potential of electrochemical dealloying of Ag₃₀Zn₇₀ precursor alloy, the optimized nanoporous silver (NPS) can be obtained and characterized by XRD, SEM and EDS. The effects of PVP organic molecules, dealloying time and potential on the NPS formation,and formaldehyde detecting sensitivity of NPS has been investigated by using cyclic voltammetry in alkaline solutions.

In this experiment, the Ag₃₀Zn₇₀ precursor alloy was fabricated by high frequency induction melting and rapid solidification, which consisted of ε phase on the base of XRD patterns. After electrochemically dealloying in 0.1 M HCl solution containing PVP, NPS with characteristic pore size of about 136~240 nm was formed.

With the dealloying time increasing, the ε phase of Ag₃₀Zn₇₀ alloy was transformed to NPS gradually.The long time dealloying process will result in the coarsening of ligaments and the increase of pore size in nanoporous structure to some extent. The voltage will speed up the dealloying process significantly and accelerate the coarsening process easily, the pore size of nanoporous structure thus became larger and non-uniform. And the coarsening process even leads to the complete collapse of the porous structure to form large granular Ag particles. The polarization curves of Ag₃₀Zn₇₀ alloy in 0.1 M HCl with different PVP introduction show that the anodic dissolution can be suppressed by PVP. As the result, the nanoporous structure is optimized after electrochemical dealloying in 1.0 g/L PVP 0.1 M HCl solution for 6 ks with the applied potential of 0.20 V. The CV curves of NPS in 0.1 M KOH solution with different HCHO concentrations indicated that the current density of HCHO oxidation increase with the HCHO concentration. After linearly fitting the peak value of HCHO oxidation current density with HCHO concentration, the detection sensitivity is 0.28, and the correlation coefficient R can reach 0.99, which indicates that the nanoporous silver has superior detection performance for the formaldehyde in the range of 10~100 mM.

Keywords: Nanoporous silver; Electrochemical dealloying; Introduction of polyvinylpyrrolidone; Detection of formaldehyde; Cyclic voltammetry

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 纳米多孔材料 1

1.1.1 纳米材料的研究 1

1.1.2 纳米多孔金属材料的研究 1

1.2 纳米多孔金属材料的制备 1

1.2.1 常规多孔制备方法 2

1.2.2 脱合金制备纳米多孔结构方法 2

1.2.3 脱合金过程机理及影响因素 2

1.3 纳米多孔材料的性能及应用 4

1.3.1 超级电容器 4

1.3.2 表面增强拉曼散射 4

1.3.3 催化性能 5

1.4 研究目的及意义 5

第二章 实验内容及方法 7

2.1 实验样品制备 7

2.2 实验路线及方法 8

2.3 实验分析与表征 9

2.3.1 X-射线衍射（XRD） 9

2.3.2 场发射电子显微镜（FE-SEM） 9

2.3.3 能谱分析（EDS） 9

2.3.4 电化学实验 10

第三章 纳米多孔银的制备及其甲醛检测性能研究 11

3.1 脱合金时间对纳米多孔银结构的影响 11

3.1.1 不同浓度PVP酸性溶液中Ag₃₀Zn₇₀的活化溶解过程 11

3.1.2 电化学脱合金过程电流与时间的关系 12

3.1.3 时间对电化学脱合金样品成分的影响 13

3.1.4 时间对电化学脱合金样品微观形貌的影响 13

3.2 脱合金电压对纳米多孔银结构的影响 16

3.2.1 不同电压脱合金过程电流与时间的关系 16

3.2.2 电压对电化学脱合金样品成分的影响 17

3.2.3 电压对电化学脱合金样品微观形貌的影响 19

3.3 纳米多孔银的甲醛催化性能 21

3.3.1 前驱体Ag₃₀Zn₇₀合金碱性溶液中的循环伏安行为 21

3.3.2 纳米多孔银的甲醛催化性能研究 22

3.3.3 纳米多孔银的甲醛检测性能研究 24

第四章 结论 27

参考文献 29

发表论文及项目 33

致 谢 34

请支付后下载全文，论文总字数：28356字