【作者】 闫秀玲；

【导师】 丁轶；

【作者基本信息】 山东大学 ， 物理化学， 2011， 博士

【摘要】 本论文主要是将脱合金化法制备的纳米多孔金及其修饰材料应用于电化学检测、燃料电池以及生物载体方面。主要内容包括纳米多孔金对水合肼的电催化氧化及检测研究、纳米多孔金作为电极材料对直接水合肼/过氧化氢燃料电池性能的研究、纳米多孔金和铂修饰纳米多孔金分别作为阳极材料对葡萄糖燃料电池性能的初步探索以及纳米多孔金作为载体固载木聚糖酶,对木聚糖的生物催化研究。本论文旨在探索纳米多孔金及金基纳米多孔金属等材料在电化学检测、燃料电池和生物催化等方面的应用研究。1.纳米多孔金对水合肼的电化学检测纳米多孔金(NPG),是通过脱合金(AuAg)法制备的一种催化剂,本章系统地研究了NPG对水合肼的电催化氧化。用循环伏安法(CV)和计时电流法,在不同扫速和pH以及不同水合肼浓度条件下,研究了水合肼的电化学氧化行为。与普通块体金相比较,NPG表现出低的过电位和高的氧化电流等优良性能,水合肼氧化的起峰电位比较低约为-400 mV,比普通块体金至少负移200 mV。峰电流与扫速的平方根成线性关系说明NPG对水合肼的电氧化是受扩散控制的。通过计时电流法实验计算出水合肼的扩散系数为1.68×10-5cm2s-1,与文献报道相一致。水合肼浓度在100 nM～10.1μM区间时,NPG对水合肼氧化的电流响应与其浓度成正比,检测限可以达到16.7 nM,说明了它具有高灵敏特性,这对低浓度水合肼的检测是非常有意义的。实验结果阐明了NPG这种催化剂可以作为优良的电化学传感材料。2.纳米多孔金为电极材料的N2H4/H202燃料电池性能研究NPG薄膜是一种对水合肼和过氧化氢都具有高催化活性的催化剂。这种新颖的高活性电极薄膜材料可应用于直接水合肼／过氧化氢燃料电池(DHHPFC)中。本文探讨了不同孔径NPG对N2H4氧化和H202还原的电催化性能,同时着重研究了在以NPG同时作为阴极和阳极催化剂时DHHPFC的电池性能。测试结果表明,在相同测试条件下,NPG作为催化剂比相同载量商业Pt/C的功率密度高出至少一个数量级。这些实验结果表明NPG是一种拥有高催化性能的的非铂催化剂,在相关燃料电池领域具有潜在的应用价值。3.纳米多孔金属为电极材料的葡萄糖燃料电池(DGFC)性能研究(1)NPG为电极材料的DGFC性能研究采用电腐蚀法制得12 nm左右小孔径NPG样品,将其用于DGFC性能测试。首先对比了NPG在中性与碱性条件下对葡萄糖的电氧化性能,实验结果表明碱性条件下NPG对葡萄糖的催化性能远大于中性条件的。讨论了碱浓度对催化性能的影响；其次,研究了NPG为催化剂的DGFC性能。探讨了温度对DGFC性能的影响,实验结果表明随着温度升高,电池性能得以提高。(2)NPG-Pt为电极材料的DGFC性能研究通过在NPG上化学镀一薄层Pt制备而成的NPG-Pt薄膜,是一种多孔Au-Pt双金属纳米材料,用这种材料研究了葡萄糖的电氧化和燃料电池性能测试。NPG-Pt的结构通过SEM、TEM和XRD等手段来表征。将NPG-Pt作为阳极催化剂(Au和Pt载量分别为0.3 mg cm-2和60μg cm-2),将商业Pt/C作为阴极催化剂,燃料电池性能测试结果显示DGFC在碱性体系比中性环境性能要好得多。NPG-Pt材料有望作为一种有前景的低贵金属载量的催化剂应用于碱性葡萄糖燃料电池。4.纳米多孔金为载体固定木聚糖酶的催化性能研究NPG这种高表面积金属海绵,具有孔径可调和生物兼容性良好等特点,被证明是一种优良的木聚糖酶载体材料。结构分析表明木聚糖酶是通过Au-S键固定到NPG上,是一种单层吸附过程。对固载酶的活性和稳定性不同实验条件下进行了研究。结果显示,固载酶的活性可以保持达到自由酶活的80%。更重要的是,这种新颖的生物催化剂表现出良好的稳定性。即使经过十个连续循环反应,固载酶的活性仍然能够保持初始酶活的76%。更多还原

【Abstract】 This paper is focusing on applications of nanoporous gold (NPG) in electrochemical catalysis, fuel cell and enmzy immobilization. Investigations are based on several aspects mainly including:electrochemical detection of hydrazine by NPG, direct N2H4/H2O2 fuel cell based on NPG, glucose fuel cell based on NPG and NPG-Pt, xylanase immobilized on nanoporous gold as a highlyefficient biocatalyst.1. An effective and rapid electrochemical detection of hydrazine by NPGNPG membranes prepared by dealloying AgAu alloys in concentrated nitric acid towards hydrazine electrochemical oxidation were studied. Compared with bulk gold, NPG shows not only the enhanced current but lower overpotential of hydrazine oxidation. The diffusion coefficient of hydrazine was examined to be 1.68×10-3 cm2 s-1 using chronoamperometry. In addition, it can be found that the behavior of hydrazine oxidation on NPG depends strongly on the pH value of the solution. A detection limit of 16.7 nM hydrazine can be determined by high sensitive NPG. These results indicate that NPG can be employed to be as an efficient electrode material of electrochemical sensors for hydrazine detection in solution.2. A platinum-free direct N2H4/H2O2 fuel cell based on NPGDealloyedNPG is found to exhibit high electrocatalytic properties toward both hydrazine (N2H4) oxidation and hydrogen peroxide (H2O2) reduction. This observation allows the implementation of a direct hydrazine-hydrogen peroxide fuel cell (DHHPFC) based on these novel membrane electrode materials. The effects of fuel and oxidizer flow rate, concentration and cell temperature on the performance of DHHPFC are systematically investigated. With a loading of 0.1 mg cm-2 Au on each side, an open circuit voltage of 1.2 V is obtained at 80℃with a maximum power density 195 mW cm-2, which is 22 times higher than that of commercial Pt/C as electrocatalysts at the same noble metal load. NPG thus holds great potential as an effective and stable platinum-free electrocatalyst for DHHPFCs.3. NPG and Pt-decorated NPG for DGFC(1)NPG for DGFC The NPG with 12 nm pore size was obtained by electrochemical dealloying under anodic potential, and using it as catalyst for DGFC performance studying. Activity of glucose electrocatalytic oxidation on NPG was investigated in neutral and alkaline solution. The results indicated that the activity in alkaline was higher than that in neutral solution for glucose oxidation. Then e plored the performance of DGFC on NPG, the results illustrated that the performance of DGFC was improved with the increasing of temperature.(2) NPG-Pt for GDFCPt-decorated nanoporous gold (NPG-Pt), created by depositing a thin layer of Pt on NPG surface, was proposed as an active electrode for GDFC in neutral and alkaline solutions. The structure and surface properties of NPG-Pt were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD). A direct glucose fuel cell (DGFC) was performed based on the novel membrane electrode materials. With a low precious metal load of less than 0.3 mg cm-2 Au and 60μg cm-2 Pt in anode and commercial Pt/C in cathode, the performance of DGFC in alkaline is much better than that in neutral condition.4. Xylanase immobilized nanoporous gold as a biocatalystNPG, a nanostructured metallic sponge with tunable porosity and excellent biocompatibility, was employed as an effective support material for xylanase immobilization. Structure analyses revealed that the immobilization of xyalanse was realized via chemical bonding of sulphur end-groups with gold surface atoms, suggesting a characteristic self-assembled monolayer type adsorption process. The activity and stability for the immobilized enzyme were investigated under different conditions. And the immobilized enzymes were found to keep as high as 80% of the activity of free ones. More importantly, these novel composite nanobiocatalysts showed quite impressive stability. Even after ten reaction cycles, this bio-nanocomposite could still retain76% of the initial activity.更多还原