不同方法制备的Pd基催化剂对乙醇电催化性能的研究

发布时间：2018-03-10 22:18

本文选题：乙醇氧化反应　切入点：石墨烯　出处：《河北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：直接乙醇燃料电池(DEFCs)已经被公认为是非常有前途的能量转换器。它可以直接把乙醇中储存的化学能转换成电能。在本论文中,除了用水热法制备Pd基催化剂之外,还采用了以水热法为基础,在电沉积过程中通过循环伏安法、计时电流法制备石墨烯负载的Pd基催化剂。利用SEM和TEM表征方法观察催化剂的结构和形貌。利用循环伏安法、计时电流法和阻抗法等一系列电化学测试方法探究催化剂对乙醇的电催化活性。主要实验内容如下:1.首先,我们将PdO和石墨烯在一定条件下热解,制得的样品固定在玻碳(GC)电极上,然后就可以得到经过热解处理的PdO/G负载的玻碳电极。我们采用了循环伏安扫描的方法,在一定的电势范围内,更换了四种不同的扫速对上述制得的样品进行扫描,循环圈数均为50圈,这样就得到了四种不同扫速处理的PdO/石墨烯负载的GC电极,在这项工作中,扫速分别为5、10、50和90mV s-1,上述制得的催化剂记为a、b、c和d。样品的形貌特征主要通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征。所制备的催化剂对乙醇氧化反应(EOR)的电催化活性主要通过循环伏安法(CV)和计时电流法进行测试。电化学测试结果表明,扫速为10mV s-1制得的PdO/G催化剂的电催化性能最好。该催化剂优于其他催化剂的主要原因是它的Pd含量相对较多并且粒径相对较小。2.将PdO和石墨烯组成的悬浮溶液放入马弗炉中,在200℃下煮沸2小时,过滤并干燥,将最后所得样品表示为PdO/G材料。然后,将样品固定在玻碳(GC)电极上,产生PdO/G涂覆的GC电极。最后,在含有PdCl_2和Na2SO4的溶液中,以10mV s-1的扫描速率,通过恒电位的方法扫描制备各种循环圈数(0,20,50和80个循环)的电极,这样就产生四种PdO/G电极(记为催化剂a、b、c和d),表示为电位扫描周期(PSC)处理的PdO/G电极。样品的形貌主要通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征。PSC处理的催化剂对乙醇氧化反应(EOR)的电催化能力主要通过循环伏安法(CV)和计时电流法(CA)检测。电化学结果表明,通过50个循环处理的PdO/G催化剂(催化剂c)在所有制备的催化剂中表现出了最好的电催化活性。与其它催化剂相比,较小的粒径和较高的金属Pd含量被认为是催化剂c对EOR优异的电催化活性的主要原因。实验结果表明,扫描周期是一种可以提高PdO/G复合材料对EOR电催化活性的方法。3.通过热解法制备PdO和石墨烯复合材料,然后将得到的复合材料涂覆在玻碳电极上,在含有PdCl_2和Na2SO4的溶液中,通过计时电流法,施加不同的负电位(-0.65V,-0.75V和-0.85V)制备出三种PdO/G电极,分别记为催化剂a、催化剂b和催化剂c。催化剂的结构和形貌主要通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征。催化剂对乙醇的电催化活性主要通过循环伏安法、计时电流法和阻抗法检测。电化学测试结果表明,催化剂b对EOR的催化效果更好。因为催化剂b的颗粒粒径最小,并且与其他催化剂相比,催化剂b中金属Pd的含量最多,所以我们认为催化剂b对乙醇的电催化效果最好。4.将PdO与PdCl_2按摩尔比为1:1放入玻璃瓶中,然后把石墨烯放入到玻璃瓶中,超声30min,制得PdO、PdCl_2和石墨烯组成的悬浊液,将悬浊液放入马弗炉中,在200℃分别煅烧3h、4h和5h,从而制得石墨烯负载的Pd基催化剂(记为催化剂a、催化剂b和催化剂c)。用SEM和TEM观察催化剂的结构和形貌,用循环伏安法、计时电流法和阻抗法等一系列电化学方法探究催化剂的电氧化性。从EDS图中分析可得,催化剂b中金属Pd的含量最高,结合SEM、TEM图谱分析可得,催化剂b的颗粒粒径最小。并且电化学测试结果表明,催化剂b对EOR的催化效果更好。因此我们认为,催化剂b对乙醇的电催化活性最好。
[Abstract]:Direct ethanol fuel cell (DEFCs) has been recognized as a very promising energy converter. It can be directly stored in the ethanol chemical energy into electrical energy. In this paper, in addition to hydrothermal preparation of Pd catalysts, also by hydrothermal method as the foundation, by cyclic voltammetry the electrodeposition process, the preparation of Pd based catalysts supported on graphene chronoamperometry method. To observe the structure and morphology of the catalyst using SEM and TEM characterization methods. Using cyclic voltammetry, chronoamperometry and electrochemical impedance method and a series of test methods on electrocatalytic activity for ethanol catalytic agent. The main contents are as follows: 1. first experiment we will, PdO and graphene pyrolysis under certain conditions, the prepared samples immobilized on glassy carbon electrode (GC), then you can get through the glassy carbon electrode pyrolysis PdO/G load. We use cyclic voltammetry Scanning method in a certain range of potential, the replacement of the four different scan rate scan of the prepared samples, the number of cycles was 50 laps, so that you get the GC electrode four different scan rate processing PdO/ graphene load, in this work, the sweep speed respectively. 5,10,50 and 90mV s-1, the prepared catalyst is denoted as a, B, C and D. morphology of the sample by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization. The prepared catalysts for ethanol oxidation (EOR) electrocatalytic activity mainly by cyclic voltammetry (CV) and chronoamperometry test. The electrochemical test results show that the sweep speed for the electrocatalytic performance of PdO/G catalyst 10mV S-1 was the best. The main reason for the catalyst is better than that of other catalysts is Pd the content of the relatively large particle size is relatively small and.2. PdO and graphene. The suspension solution into the muffle furnace, under the temperature of 200 DEG C to boil for 2 hours, filtering and drying, the final sample expressed as PdO/G material. Then, the sample was immobilized on glassy carbon electrode (GC), GC PdO/G coated electrode. Finally, the solution containing PdCl_2 and Na2SO4, with the scan rate 10mV s-1, by scanning the potentiostatic method to prepare a variety of number of cycles (0,20,50 and 80 cycles) of the electrode, resulting in four kinds of PdO/G electrode (denoted as B, catalyst a, C and D), expressed as a potential scanning cycle (PSC) PdO/G electrode treatment. The morphologies of the samples by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization of.PSC catalysts for ethanol oxidation treatment (EOR) electrocatalytic ability mainly by cyclic voltammetry (CV) and chronoamperometry (CA) detection. The electrochemical results show that through 50 cycles of treatment of the PdO/G catalyst (C catalyst ) in all the catalysts prepared showed the best electrocatalytic activity. Compared with other catalysts, smaller particle size and higher content of metal Pd is thought to be a catalyst for C EOR with excellent electrocatalytic activity for the main reason. The experimental results show that the scanning cycle is a method to improve the electrocatalytic EOR the activity of the PdO/G composite material.3. and preparation of PdO graphene composite materials by pyrolysis method, and the obtained composite material coated on glassy carbon electrode, in aqueous solution containing PdCl_2 and Na2SO4, chronoamperometry by applying a negative potential different (-0.65V, -0.75V and -0.85V) were prepared by three kinds of PdO/G electrode. They were recorded as a catalyst, the structure and morphology of catalyst B and C. catalysts by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization of the catalyst. The electrocatalytic activity for ethanol mainly by cyclic volt ANN method, chronoamperometry and impedance detection method. The electrochemical test results show that the better catalytic effect of catalyst B on EOR. Because the particles of B catalyst particle size, and compared with other catalysts, the most content of metal Pd B catalyst, so we think that the electrocatalytic effect of B catalyst for ethanol best.4. PdO with the PdCl_2 molar ratio of 1:1 in a glass bottle, then put the graphene into glass bottles, ultrasonic 30min, preparation of PdO, PdCl_2 and graphene is composed of suspension, the suspension is placed in a muffle furnace, at a temperature of 200 DEG C respectively 4H and 5h, 3h burning, so as to prepare Pd based catalysts supported on graphene (remember catalyst a, catalyst B and C catalyst). Structure and morphology of SEM and TEM on the catalyst, using cyclic voltammetry, chronoamperometry and electrochemical impedance method and a series of methods to explore the electro oxidation of catalyst. From the EDS diagram analysis The content of metal Pd in catalyst B is the highest. Combined with SEM and TEM analysis, the particle size of catalyst B is the smallest. The electrochemical test results show that the catalyst B has better catalytic effect on EOR. Therefore, we believe that the catalyst B has the best electrocatalytic activity for ethanol.

【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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