银纳米晶制备及其催化性能的研究.pdf

合肥工业大学硕士学位论文银纳米晶的制备及其催化性能研究姓名:张孟如申请学位级别:硕士专业:应用化学指导教师:柴多里 201204 合肥工业大学硕士学位论文银纳米晶的制各及其催化性能研究摘要本论文以硫酸银和硝酸银为银源,分别采用微波辅助液相合成法和气一固相还原法制备了银纳米晶。利用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)等方法对所制备的银纳米晶进行了分析表征,结果显示:采用微波辅助液相合成法制各的银纳米晶为纯相立方晶型,粒径较小、分布较窄。气一固相还原法制备出黑色银纳米晶,此种方法操作简单,反应条件易控制。探讨了硝酸银浓度、硝酸银和聚乙烯吡咯烷酮(PVP)不同用量比等因素对所制银纳米晶的尺寸和形貌的影响,以及银纳米晶可能的形成机理。催化实验结果表明:以微波辅助液相合成法制备的银纳米晶为催化剂,在银纳米晶与双氧水构成的氧化体系氧化亚甲基蓝显示了较高的氧化效果;在银纳米晶和硼氢化钾构成的还原体系中对亚甲基蓝亦给出了较好还原效果。从而表明银纳米晶在催化氧化和催化还原反应中均具有催化活性的特殊性能。进一步探讨了催化剂银纳米晶的用量、反应温度、反应时间等因素对亚甲基蓝氧化还原效果的影响,催化剂经多次重复使用后仍具有较高的催化活性。催化氧化亚甲基蓝的反应符合一级动力学方程,以及可能的催化反应机理。在还原亚甲基蓝的反应中,采用气一固相还原法制备的银纳米晶的催化性能不明显,这可能是因为所制备的银纳米晶粒径大且有部分团聚从而影响了其表面催化性能。关键词:气一固相还原法,微波辅助液相合成法,银纳米晶,催化活性合肥工业大学硕士学位论文 Preparation and Investigation ofCatalytic Properties ofSilver Nanocrystals ABSTRACT Intiffsthesis,silver sulfate and silver nitrate were used as silver source,through microwave—assisted liquid phase synthesis method and gas—solidphase reduction method seperately toprepare nanocrystals were characterized by X—ray diffraction(XaD),transmission electron microscopy(TEM),scanning electron microscope (SEM).The resultsshowed thatsilvernanocrystals prepared withmicrowave—assisted liquid phase synthesis were allcubic incrystalphase,and silvernanoparticles with small sizeand narrow size silver nanocrystals were prepared by gas—solid phase reduction —solid phase reduction method provided asimple way toprepare silvernanocrystals,and thereaction conditions were easy tobe influenceof silvm’nitrate concentration,dosage ratiosofsilvernitrate topolyvinylpyrrolidone(PVP)on thesizeandmorphology ofsilvernanocrystals were studied and theformation mechanism ofsilvernanocrystals were investigated. The catalytic tests results showed that silver nanocrystals prepared with microwave—assisted liquid phase synthesis method as catalysts,which proved tobe an excellent oxidation intheoxidation system of silvernanocrystals andhydrogen peroxide. Silvernanocrys