【作者】 赵宏；

【导师】 郑军伟； 赵斌元；

【作者基本信息】 苏州大学 ， 物理化学， 2013， 博士

【摘要】 特殊形貌的银纳米材料会呈现出与形貌相关的特殊的光学性能和催化性能。通过不同的合成方法控制合成不同形貌的银纳米结构一直都是具有挑战性的研究工作。本论文围绕这一研究主题，本着绿色合成的理念，利用生物质碳电化学转化机制，提供了一种缓慢稳定的晶体生长环境，通过改变银前驱体的浓度以及碳负载的无机离子种类等方式调控合成了花状、片状、带状和树枝状不同形貌的银纳米单晶，并研究其生长机制。同时利用了简单有效的合成方法合成出银包覆纳米复合结构，并研究了它们的催化和抑菌性能。本文主要开展了以下几个方面的研究工作。1.利用生物质碳表面官能团电化学转化的机制调控生长不同形貌的单晶银本项研究所做的工作就是仅利用规则的成型活性炭和银氨溶液获得了大量的单晶带银或片银。基于在生物质成型活性碳（biomass-derived monolithic activatedcarbon, MAC）上的还原基团可以电化学转化来维持银或其他贵金属生长的机理，通过利用AgCl作为晶种，选择银氨溶液作为前躯体，以及从前驱体溶液中释放出的OH-能使消耗的还原基团再生这三方面的结合，我们实现了绿色低价的单晶银的种植，并形成了单晶银的生长机制。本项研究工作进一步说明了在多孔材料上的功能基团可以实现电化学转化来扩大其应用范围。2.利用生物质碳的电化学转化及所负载无机离子调控合成枝状银纳米结构通过改变生物质碳上负载的无机离子，当碳上负载磷酸根离子时，可以在碳上长出树枝状银。比较碳上负载的氯离子、氢氧根离子和磷酸根离子对调控银纳米结构形貌生长的影响，不同的负载离子对应于不同的银的形貌。并探讨了相应的生物碳的电化学生长机制。3.利用生物质碳的电化学转化机制及低浓度的银前驱体溶液合成纳米带银基于生物质碳与银所形成的原电池生长单晶银的原理，以氧化银为前驱体，提供了单晶纳米带银的生长环境，利用温度、距离等生长环境来控制银离子释放浓度，生长出不同颜色、不同尺寸的纳米带银单晶。4.银纳米的核-壳包覆复合结构的合成(1)利用植物提取物与银形成碳包覆银的纳米结构，并考察了植物提取物的量、反应温度等对银纳米包覆结构的影响。(2)用氢气还原得到不同尺寸的银纳米粒子，无表面活性剂包覆的银纳米粒子与壳聚糖混合，形成了壳聚糖包覆银的纳米结构，并对其进行了抑菌性能测试。发现二者具有良好的协同抑菌性能。(3)银与二氧化硅微球的包覆结构的制备。通过敏化和化学沉积两步合成了银与二氧化硅微球的纳米包覆结构，并进行催化性能的测试，发现对硝基化合物转化为氨基化合物具有良好的催化性能。更多还原

【Abstract】 The intrinsic properties of silver nanostructures, such as optical and catalystproperties, are mainly detennined by their shapes and sizes. Shape-controlled synthesisof silver nanostructures has been and continues to be an area of challenging andactive research. As these issues to be addressed, we create a stable environment for thegrowth of single crystalline silver based on the principle that reductive groups inbiomass-derived monolithic activated carbon (MAC) could be electrochemicallyconversed to sustain the growth of silver and other noble metals. Then we show thatdifferent morphologies single crystalline silver including silver nanoflowers, nanoplates,belts or dendritic grow abundantly on the surface of MAC in a high-quality, low-costand eco-friendly way, and their growth mechanism are studied. A simple and effectivesynthesis method making silver coat or coated composite structure is presenting, andcatalytic and inhibitory properties of composite structure are tested. The followingresearches have been carried out.1.Tunable growth of different morphologies single crystalline silver by galvaniccell mechanism on MACHere we show that a large scale strip or flake single crystal silver grow throughbiomass-derived monolithic activated carbon (MAC) with [Ag(NH3)2]OH solution only.Based on the principle that reductive groups in MAC could be electrochemicallyconversed to sustain the growth of silver and other noble metals, through introducingcubic AgCl crystal seed, selecting silver ammonia solution as precursor, and OH-setfree from precursor facilitating the regeneration of the consumed reductive groups, ourwork achieves a green low-cost “planting” of single crystal silver and follows newmechanism of silver growth. It further suggests that functional groups on porousmaterials can be electrochemically conversed for more applications.2.Dendritic silver were prepared on monolithic activated carbon (MAC)pre-absorbed with PO43-anions Dendritic silver were prepared on monolithic activated carbon (MAC)pre-absorbed with PO43-anions. It is virtal that moderate Cl-, OH-and PO43-pre-absorbed in MAC to form the corresponding morphsynthesis of silver. A galvaniccell reaction mechanism by reductive functional groups on MAC is established.3.Nanobelts silver were prepaired through a galvanic cell reaction mechanism andlower Ag+concentrationBased on the principle that reductive groups in MAC could be electrochemicallyconversed to sustain the growth of silver, through introducing Ag2O precursor, selectinglower Ag+concentration，a continually grow mechanism of single crystal belts silver isestablished. Nanobelts silver with different colours and sizes were obtained by changingtemperature and distance.4.The synthesis of core-shell silver composite structure(1) Blending plant extracts and silver nanoparticles with ultrasonic, a carbonencapulsated silver composite structure was produced. The amount of extract andreaction temperature are important to the composite structure.(2) The silver nanoparticles with different sizes was prepaired by hydrogenreduction. Blending silver nanoparticles and chitosan, a chitosan-encapulsated silvercomposite structure was formed. Chitosan-encapulsated silver composite structure havesynergistic antibacterial effect on Escherichia coli.(3) The synthesis of silver-encapulsated silica microspheres composite structure.Silver-encapulsated silica microspheres were prepared by sensitization and chemicaldeposition. And that, these composite structure have catalytic reduction ofp-nitrophenol.更多还原