【作者】 王艳丽；

【导师】 张明旭；

【作者基本信息】 安徽理工大学 ， 环境工程， 2012， 博士

【摘要】 论文分别采用超声波辐射、可见光光照、简易加热和溶致液晶模板方法,制备系列纳米Pd材料,通过改变实验条件调控其微观形貌；针对空气污染物—甲醛,将不同体系制备的纳米Pd修饰到玻碳电极表面,利用三电极化学系统,通过循环伏安法系统的研究了不同催化剂修饰电极对甲醛的电催化氧化,为拓展甲醛的电化学行为研究奠定了理论基础。1.采用超声波辐射、可见光光照和简易加热合成方法,以PdCl2为金属前驱物,在水-乙醇混合溶液中,分别在没有模板.CTAB表面活性剂模板和CTAB-SDS混合表面活性剂模板等反应体系内制备纳米Pd催化剂,采用XRD、TEM、UV、 HRTEM和低温氮吸附-脱附等技术进行了表征。考察了不同实验条件(无模板、CTAB模板和CTAB-SDS模板)对纳米催化剂微观形貌的影响,探讨了Pd2+的还原机理,系统研究了所制备的纳米催化剂修饰玻碳电极对甲醛的电催化氧化活性。通过三种方法相同实验条件下对甲醛的电催化活性和相对标准偏差比较,结果表明,以CTAB-SDS混合表面活性剂为软模板,采用简易加热合成方法制备的纳米Pd修饰电极对甲醛的电催化活性是最好的。最佳实验条件是加热3h,CTAB与SDS的摩尔比为100：1,该合成条件的纳米催化剂平均粒径为(30±2)nm,呈规则形貌,特别是四边形纳米催化剂的产率较高,利用其修饰电极对甲醛的电催化氧化峰Ⅰ的电流值为1345μA,峰电流的相对标准偏差仅为0.72%。2.在25℃,构建盐水/SDS/环己烷/正戊醇三元溶致液晶体系,利用小角XRD、DSC和偏光显微分析等技术手段,绘制三元相图,确定液晶区域；以溶致液晶为模板,分别在避光、白炽灯光照及紫外光辐射等不同实验条件下合成纳米Pd催化剂,考察了不同实验条件对其微观形貌的影响,并利用其修饰电极对甲醛的电催化氧化进行了系统研究。通过三种实验条件对甲醛的电催化氧化峰Ⅰ的电流值和相对标准偏差比较,结果表明,在白炽灯光照条件下,制备的纳米Pd催化剂修饰电极对甲醛的电催化活性是最好的。最佳实验条件是反应时间6h,白炽灯光照强度100W；该合成条件的纳米粒子呈菱形、五边形和四方形,粒径为(31±2)nm,且分布较集中,和避光条件制备的纳米Pd催化剂的微观形貌比较,光照6h与避光24h的纳米催化剂的形貌和尺寸相类似,表明光和热的作用可以加速纳米粒子的生长,利用此材料修饰玻碳电极,氧化峰Ⅰ的电流值为988μA,峰电流的相对标准偏差为3.89%。3.比较简易加热方法和溶致液晶的优化实验方案,表明采用简易加热合成方法制备纳米催化剂修饰电极对甲醛的催化行为足最好的。更多还原

【Abstract】 The series nano-Pd materials were prepared via ultrasonic irradiation, visible lighting, simple heating and lyotropic liquid crystal (LLC) methods, respectively. The micro-morphology was controlled by change of experimental conditions. The electrocatalytic properties of the series nano-Pd materials modified glassy carbon electrode(Pd/GCE) for formaldehyde oxidation were investigated by cyclic voltammetry(CV) using three electrode system. The thesis was not only to obtain some kinds of simple synthetic methods for preparing nano-Pd materials with controllable morphology and size, but to supply theoretical basis for development of formaldehyde on the electrochemistry.1. The nano-Pd materials were prepared via ultrasonic irradiation, visible lighting, and simple heating methods separately in the palladium (Ⅱ) chloride H2O/EtOH solution without template and with the soft template of hexadecyl trimethyl ammonium bromide(CTAB) and the mixture of CTAB and sodium dodecyl sulfonate(SDS), respectively. The samples were characterized by XRD、TEM、UV、HRTEM and low temperature nitrogen adsorption-desorption. The effects of the experimental conditions on the micro-morphology of palladium nanoparticles were investigated and the reaction mechanisms were also discussed. The electrocatalytic properties of the nano-Pd modified glassy carbon electrode (Pd/GCE) for formaldehyde oxidation had been also studied systematically by cyclic voltammetry. Comparison of the electrocatalytic activity for formaldehyde and the relative standard deviation using three methods under the same experiment conditions, the results indicate that the nano-Pd materials wich were prepared via simple heating methods with the soft template of the mixture with a distributed size of (30±2) nm, has the best excellent electrocatalytic activity for the oxidation of formaldehyde with the peak I value of1345μA and the RSD (relative standard deviation) of0.72%. The optimized experimental condition was that the molar ratio of CTAB:SDS was100:1and the reaction time was3h. Under the optimized condition, the nano particles were easy to form regular morphology, such as quadrilateral nanoparticles.2. The phase diagrams of the ternary system of brine/SDS/cyclohexane/n-pentanol were determined at25℃. The small angle X-ray diffraction, DSC and the polarizing microscope were used for determining the structures of various samples in brinc/SDS/cyclohexane/n-pentanol liguid crystalline regions. The nano-Pd materials were prepared via without light, visible lighting and ultraviolet light methods respectively with lyotropic liquid crystal as soft template. The effects of the experimental conditions on the micro-morphology of palladium nanoparticles were investigated as well. The electrocatalytic properties of the nano-Pd modified glassy carbon electrode (Pd/GCE) for formaldehyde oxidation had been also studied systematically by cyclic voltammctry. Comparison of the electrocatalytic activity for formaldehyde and the RSD under the three experiment conditions, the results indicate that the nano-Pd materials wich were prepared via visible lighting methods with a distributed size of (31±2) nm. has the best excellent elcctrocatalytic activity for the oxidation of formaldehyde with the peak I value of988μA and the RSD of3.89%. The optimized experimental condition is that the strength of incandescent lamp was100W and the reaction time was6h. Under the optimized condition, the nano-particles were rhombus, pentagonal and regular quadrilateral. The size and morphology of the nano-Pd were similar to synthesis in24h without lighting and6h lighted. The results showed that the growth of the nano-Pd accelerated because of the function of light and heat.3. Comparison of the electrocatalytic activity for formaldehyde under the optimized experiment conditions, the results indicate that the glassy carbon electrode(Pd/GCF) was modified by nano-Pd materials which were prepared via simple heating methods, had the better electrocatalytic activity for the oxidation of formaldchyde.更多还原