纳米铂基催化剂的制备与性能研究
发布时间：2018-10-12 08:28
【摘要】：纳米材料因其所具备独特的物理性能、化学性能,一直备受广大科研工作者的青睐。到目前为止,关于纳米材料的研究已经取得丰硕的成果,纳米材料已经被广泛的应用到光学传感元件、仿生学、催化以及药物化学等领域。随着近年来对燃料电池研究的兴起,催化剂作为影响燃料电池性能和大规模应用的关键因素之一成为了人们关注的焦点。贵金属铂由于具有其他材料所不具备的高催化活性,常被选做反应催化剂材料。但是贵金属铂催化剂同样有着明显的缺点,即昂贵的成本以及容易发生碳中毒现象。本文通过模板法成功制备得到了纳米Pt-Ru合金催化剂、纳米Pt-Ni合金催化剂以及Pt-Ru合金纳米线催化剂三种材料,分别对三种材料进行性能测试发现,相比较于目前商业化使用的铂黑催化剂,本中得到的三种材料具有更高的电催化活性、更强的抗碳中毒能力以及更低的成本,主要工作如下：通过使用表面活性剂P123作为软模板,抗坏血酸(AA)还原制备得到了纳米Pt-Ru合金催化剂。通过电化学催化实验研究发现,由于堆积成球型结构的催化剂颗粒大小在3nm左右且催化剂表面具有介孔结构,所以相比较于商业铂黑催化剂具有更大的电催化活性表面积(ECSA);同时由于引入金属Ru与Pt形成了合金结构,从而增加了催化剂抗碳中毒的能力,并且因为价格较低的Ru的引入,使得催化剂材料的成本相对于由纯铂构成的商业铂黑催化剂而言有所下降。通过选用非离子表面活性剂Brij58作为软模板,利用硼氢化钠在冰浴中还原,成功制备得到了不同含Pt质量分数的纳米Pt-Ni合金催化剂材料。制备得到的合金催化剂颗粒大小在6-8nm的范围,颗粒分布均匀尺寸均一。通过电化学催化实验研究发现,六种不同质量分数的电催化活性面积均明显高于商业铂黑催化剂,同时由于引入了金属材料Ni使得催化剂抗碳中毒的能力得到了增强,并且因为Ni低廉的价格,大大降低了催化剂的成本。同时通过对比六种不同含量的催化剂材料性能发现Pt wt%=50%的样品具有最高的电催化活性表面积42.9 m2 g-1,在催化甲醇氧化实验中具有最大的正向扫描峰位电流密度(ECSA标准化后)0.84mA cm-2,较高的正反向扫描峰位电流密度比If/Ib=1.19。通过改进的Stober法制备了粒径为30nm的二氧化硅小球,并使用抽滤法将二氧化硅小球填充到孔径为200nm的多孔氧化铝模板中,以此复合结构为模板制备得到了三种不同含铂质量分数的Pt-Ru合金纳米线材料。合成的合金纳米线直径200nm,且均匀分布有大量直径为30nm的孔结构。通过电催化实验发现,三种样品的ECSA均大于商业铂黑催化剂,且具有更强的抗碳中毒能力以及更低的成本。三种样品中,Pt wt%=75%的样品具有最高的ECSA=38.3 m2 g-1,最大的正向扫描峰位电流密度(ECSA标准化后)0.52 mA cm-2以及高的正反向扫描峰位电流密度比If/Ib=1.57。
[Abstract]:Nanomaterials are favored by researchers for their unique physical and chemical properties. Up to now, great achievements have been made in the research of nanomaterials. Nanomaterials have been widely used in the fields of optical sensing elements, bionics, catalysis and pharmaceutical chemistry. With the development of fuel cell research in recent years, catalyst as one of the key factors affecting fuel cell performance and large-scale application has become the focus of attention. Precious metal platinum is often selected as a catalyst for reaction because of its high catalytic activity that other materials do not. However, precious metal platinum catalysts also have obvious disadvantages, such as high cost and carbon poisoning. In this paper, three kinds of nanocrystalline Pt-Ru alloy catalysts, nanometer Pt-Ni alloy catalysts and Pt-Ru alloy nanowire catalysts were successfully prepared by template method. Compared with the current commercial use of platinum black catalysts, the three materials obtained in this paper have higher electrocatalytic activity, stronger resistance to carbon poisoning and lower cost. The main work is as follows: nanometer Pt-Ru alloy catalyst was prepared by using surfactant P123 as soft template and ascorbic acid (AA) reduced. By electrochemical catalytic experiments, it was found that the size of the catalyst was about 3nm and the mesoporous structure was found on the surface of the catalyst. Therefore, compared with commercial platinum black catalysts, the electrocatalytic surface area of (ECSA); is larger than that of commercial platinum black catalysts, and the metal Ru and Pt are introduced to form alloy structure, which increases the ability of the catalyst to resist carbon poisoning, and because of the introduction of lower price Ru, The cost of catalyst material is lower than that of commercial platinum black catalyst composed of pure platinum. Nonionic surfactant Brij58 was used as soft template and sodium borohydride was used to deoxidize in ice bath. Nanocrystalline Pt-Ni alloy materials with different mass fraction of Pt were prepared successfully. The particle size of the prepared alloy catalyst is in the range of 6-8nm, and the particle size is uniform. The electrochemical catalytic experiments showed that the electrocatalytic activity area of the six different mass fractions of the catalysts was significantly higher than that of commercial platinum black catalysts, and the ability of the catalysts to resist carbon poisoning was enhanced by the introduction of metal material Ni. And because of the low price of Ni, the cost of catalyst is greatly reduced. At the same time, by comparing the performance of six kinds of catalyst materials with different contents, it was found that the Pt wt%=50% sample had the highest electrocatalytic activity surface area of 42.9 m2 g-1, and the largest forward scanning peak current density (ECSA) in the catalytic methanol oxidation experiment. Higher peak current density ratio of positive and backward scanning of 0.84mA cm-2, to If/Ib=1.19. Silica pellets with diameter of 30nm were prepared by improved Stober method and filled into porous alumina template with pore diameter of 200nm by filter method. Three kinds of Pt-Ru alloy nanowires with different platinum content were prepared by using the composite structure as template. The synthesized nanowires are 200 nm in diameter and have a large number of pore structures with 30nm diameter uniformly distributed. The results of electrocatalytic experiments showed that the ECSA of the three samples was higher than that of commercial platinum black catalysts and had stronger resistance to carbon poisoning and lower cost. Of the three kinds of samples, the sample of Pt wt%=75% has the highest ECSA=38.3 m2 g-1, the maximum peak current density of positive scan (after ECSA standardization) of 0.52 mA cm-2, and the high peak current density ratio of positive and negative scanning to If/Ib=1.57..
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1
本文编号：2265461
[Abstract]:Nanomaterials are favored by researchers for their unique physical and chemical properties. Up to now, great achievements have been made in the research of nanomaterials. Nanomaterials have been widely used in the fields of optical sensing elements, bionics, catalysis and pharmaceutical chemistry. With the development of fuel cell research in recent years, catalyst as one of the key factors affecting fuel cell performance and large-scale application has become the focus of attention. Precious metal platinum is often selected as a catalyst for reaction because of its high catalytic activity that other materials do not. However, precious metal platinum catalysts also have obvious disadvantages, such as high cost and carbon poisoning. In this paper, three kinds of nanocrystalline Pt-Ru alloy catalysts, nanometer Pt-Ni alloy catalysts and Pt-Ru alloy nanowire catalysts were successfully prepared by template method. Compared with the current commercial use of platinum black catalysts, the three materials obtained in this paper have higher electrocatalytic activity, stronger resistance to carbon poisoning and lower cost. The main work is as follows: nanometer Pt-Ru alloy catalyst was prepared by using surfactant P123 as soft template and ascorbic acid (AA) reduced. By electrochemical catalytic experiments, it was found that the size of the catalyst was about 3nm and the mesoporous structure was found on the surface of the catalyst. Therefore, compared with commercial platinum black catalysts, the electrocatalytic surface area of (ECSA); is larger than that of commercial platinum black catalysts, and the metal Ru and Pt are introduced to form alloy structure, which increases the ability of the catalyst to resist carbon poisoning, and because of the introduction of lower price Ru, The cost of catalyst material is lower than that of commercial platinum black catalyst composed of pure platinum. Nonionic surfactant Brij58 was used as soft template and sodium borohydride was used to deoxidize in ice bath. Nanocrystalline Pt-Ni alloy materials with different mass fraction of Pt were prepared successfully. The particle size of the prepared alloy catalyst is in the range of 6-8nm, and the particle size is uniform. The electrochemical catalytic experiments showed that the electrocatalytic activity area of the six different mass fractions of the catalysts was significantly higher than that of commercial platinum black catalysts, and the ability of the catalysts to resist carbon poisoning was enhanced by the introduction of metal material Ni. And because of the low price of Ni, the cost of catalyst is greatly reduced. At the same time, by comparing the performance of six kinds of catalyst materials with different contents, it was found that the Pt wt%=50% sample had the highest electrocatalytic activity surface area of 42.9 m2 g-1, and the largest forward scanning peak current density (ECSA) in the catalytic methanol oxidation experiment. Higher peak current density ratio of positive and backward scanning of 0.84mA cm-2, to If/Ib=1.19. Silica pellets with diameter of 30nm were prepared by improved Stober method and filled into porous alumina template with pore diameter of 200nm by filter method. Three kinds of Pt-Ru alloy nanowires with different platinum content were prepared by using the composite structure as template. The synthesized nanowires are 200 nm in diameter and have a large number of pore structures with 30nm diameter uniformly distributed. The results of electrocatalytic experiments showed that the ECSA of the three samples was higher than that of commercial platinum black catalysts and had stronger resistance to carbon poisoning and lower cost. Of the three kinds of samples, the sample of Pt wt%=75% has the highest ECSA=38.3 m2 g-1, the maximum peak current density of positive scan (after ECSA standardization) of 0.52 mA cm-2, and the high peak current density ratio of positive and negative scanning to If/Ib=1.57..
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1
【共引文献】
相关博士学位论文 前2条
1 王立刚;合成气直接制取二甲醚反应体系的研究[D];中国科学院研究生院（大连化学物理研究所）;2007年
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相关硕士学位论文 前3条
1 夏鹏;ZnO/HZSM-5催化溴甲烷水解制二甲醚的研究[D];湖南大学;2011年
2 李娇;Mg/Zn掺杂孔雀石和Al/Zr掺杂绿铜锌矿性质的第一性原理研究[D];太原理工大学;2015年
3 占瑛;MO/SiO_2-γ-Al_2O_3催化溴甲烷水解制甲醇和二甲醚的研究[D];华东师范大学;2015年
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