纳米多孔银的制备及其甲醛高效检测

Fabrication of nanoporous silver and its superior sensitivities to formaldehyde

摘要:

纳米多孔银因其比表面积大且活性位点密度高等特性，在甲醛高效检测领域有潜在应用。本研究在0.1 mol?L-1盐酸溶液中对Ag30Zn70合金通过化学脱合金和电化学脱合金法两种方法制备纳米多孔银，研究化学脱合金时间和电化学脱合金电压对纳米多孔银孔结构的影响以及多孔结构的甲醛检测灵敏度和有效检测范围。结果表明，在自然浸泡24小时过程中，金属间化合物ε相中Zn发生缓慢选择溶解，形成纳米多孔Ag及残存ε相的共存结构，通过化学脱合金难以制备出Ag相占比高的纳米多孔结构。通过电化学脱合金方式施加电压0.1 V极化6000 s后，可制备出孔径约80 nm的三维连续贯通的纳米多孔银结构。循环伏安测定结果表明，在0.1 mol?L-1 KOH基液中，甲醛氧化电流密度随着甲醛浓度的增加而增大，氧化电流密度与甲醛浓度在10~100 mmol?L-1范围内呈良好的线性关系，甲醛检测灵敏度为0.1。纳米多孔银在50~100 mmol?L-1的高浓度范围表现出优异的甲醛检测性能。

Abstract:

Nanoporous silver owning to large specific surface area and high densities of active sites, has a great potential for superior formaldehyde detection. Both chemical dealloying and electrochemical dealloying of Ag30Zn70 precursor alloy in 0.1 mol?L-1 hydrochloric acid solution were employed to fabricate NPS. The effects of duration time of chemical dealloying and applied potential of electrochemical dealloying on the formation of nanoporous structure and the current response of formaldehyde have been investigated. The results show that slow selective dissolution of Zn elements in intermetallic ε phase takes place during chemical dealloying of 24 h, which leads to the formation of nanoporous structure consisting of Ag and residual ε phase. Through electrochemical dealloying with applied potential of 0.1 V for 6000 s, 3D bi-continuous NPS with characteristic pore size of 80 nm was achieved. The results of cyclic voltammetry show that the oxidation current density of formaldehyde was enhanced with the increasing of formaldehyde concentration in 0.1 mol?L-1 KOH solution. The response oxidation current densities linearly depended on formaldehyde concentrations between 10~100 mmol/L, and the sensitivity of formaldehyde detection was 0.10. The present reagents of nanoporous silver had superior formaldehyde detection abilities in high concentrations of 50~100 mmol?L-1.