铜基多元合金纳米管的制备及其合金化效应对催化性能的影响
发布时间：2019-01-29 20:18
【摘要】：为了研究铜基合金纳米管的成分及其合金化效应对其电催化性能的影响,本论文以铜纳米线为模板,采用电化学置换的合成方法,分别制备了不同种类的铜基多元合金纳米管并对其性能及氧气还原反应的机理进行了研究。首先以氯铂酸为铂源,铜纳米线为前驱体模板,通过控制氯铂酸的滴加量,制备了不同成分的铜铂二元合金纳米管。制得的纳米管的直径在100-150纳米之间,壁厚15-25纳米,管长2-3微米;铜铂元素在合金纳米管壁上均匀分布。对不同成分的铜铂合金纳米管进行了电催化性能的研究。其中,成分为Cu40Pt60催化性能最优,其催化氧气还原反应的起始电位和半波电位分别超出商业Pt/C 57mV和20m V,在催化甲醇氧化过程中正负扫峰电流密度的比值约为商业Pt/C的1.57倍。材料合金化效应能够大幅提高其电催化活性。材料氧化还原反应机理研究结果表明:相较于商业Pt/C,铜铂合金中由于铜铂间的合金化效应改变了 Pt 5d轨道的电子结构,从而减弱了氢氧根与合金表面相互作用,提高了电催化反应的速率。其次,为了降低上述二元合金的成本,使用相对便宜的氯化钯替换了氯铂酸,采用相同的电化学置换方法,制备了铜钯合金纳米管。结果发现,该催化表现出优秀的催化甲醇氧化性能,大部分催化剂催化甲醇氧化的性能优于商业Pt/C。其中成分为Cu20Pd80性能最优,为了进一步探明合金化效应对催化性能的影响,在上述二元合金的基础上,又制备了铜铂钯三元合金纳米管。在三元合金纳米管中各金属元素均匀分布在合金纳米管壁上,其合金化程度达到原子级水平。由于金属间的协同效应使得三元合金具有优异的催化性能。不同成分的三元合金的催化氧气还原性能均优于商业Pt/C,其中性能最优的为Cu28.5Pt37.2Pd34.3,在酸性体系下其起始电位和半波电位分别超出商业Pt/C 88mV和49mV;在电位值为0.85V(vs.RHE)处其催化氧气还原动力学电流密度约为商业Pt/C的8倍。此外,其催化甲醇氧化的正负扫峰电流密度的比值约为商业Pt/C的1.9倍。最后,通过比较三种不同类型的合金催化剂性能,催化活性由强到弱为:铜铂钯三元合金铜铂二元合金铜钯二元合金。三元合金的高度合金化是引起高的氧气还原和甲醇氧化的电催化性能的原因之一。
[Abstract]:In order to study the effect of the composition and alloying effect of Cu-base alloy nanotubes on their electrocatalytic properties, in this paper, copper nanowires were used as templates and electrochemical replacement method was used to synthesize copper nanotubes. Different kinds of copper-based multicomponent alloy nanotubes were prepared and their properties and mechanism of oxygen reduction were studied. Firstly, using chloroplatinic acid as platinum source and copper nanowires as precursor template, copper-platinum binary alloy nanotubes with different compositions were prepared by controlling the amount of chloroplatinic acid. The diameter of the nanotubes is between 100-150 nm, the wall thickness is 15-25 nm, the length of the nanotubes is 2-3 渭 m, and the copper and platinum elements are distributed uniformly on the alloy nanotubes. The electrocatalytic properties of copper platinum alloy nanotubes with different compositions were studied. Among them, the composition of Cu40Pt60 has the best catalytic performance. The initial potential and half-wave potential of the catalytic oxygen reduction reaction are higher than commercial Pt/C 57mV and 20mV, respectively. In the process of catalytic methanol oxidation, the ratio of positive and negative sweep peak current density is about 1.57 times of commercial Pt/C. The material alloying effect can greatly improve its electrocatalytic activity. The results of redox reaction show that the electronic structure of Pt 5d orbital is changed due to the effect of copper-platinum alloying in commercial Pt/C, copper-platinum alloys, which weakens the interaction between hydroxide and the surface of the alloy. The rate of electrocatalytic reaction was increased. Secondly, in order to reduce the cost of the binary alloy, palladium chloride was used to replace chloroplatinic acid, and copper alloy nanotubes were prepared by the same electrochemical replacement method. The results showed that the catalyst exhibited excellent catalytic performance of methanol oxidation, and most of the catalysts showed better catalytic performance than commercial Pt/C.. In order to further investigate the effect of alloying effect on catalytic performance, copper platinum-palladium ternary alloy nanotubes were prepared on the basis of the above binary alloys. In the ternary alloy nanotubes, all metal elements are uniformly distributed on the wall of the alloy nanotubes, and the alloying degree reaches the atomic level. The ternary alloys have excellent catalytic performance due to the synergistic effect between metals. The catalytic oxygen reduction performance of ternary alloys with different composition is superior to commercial Pt/C,. The best performance of Cu28.5Pt37.2Pd34.3, is that the initial potential and half wave potential of Cu28.5Pt37.2Pd34.3, in acid system are higher than commercial Pt/C 88mV and 49mV respectively. At the potential value of 0.85 V (vs.RHE), the kinetic current density of catalytic oxygen reduction is about 8 times that of commercial Pt/C. In addition, the ratio of positive and negative peak current density of methanol oxidation is about 1. 9 times that of commercial Pt/C. Finally, by comparing the performance of three kinds of alloy catalysts, the catalytic activity from strong to weak is as follows: copper-platinum-palladium ternary alloy copper-platinum binary alloy copper-palladium binary alloy. The high alloying of ternary alloys is one of the reasons for the high electrocatalytic properties of oxygen reduction and methanol oxidation.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36
[Abstract]:In order to study the effect of the composition and alloying effect of Cu-base alloy nanotubes on their electrocatalytic properties, in this paper, copper nanowires were used as templates and electrochemical replacement method was used to synthesize copper nanotubes. Different kinds of copper-based multicomponent alloy nanotubes were prepared and their properties and mechanism of oxygen reduction were studied. Firstly, using chloroplatinic acid as platinum source and copper nanowires as precursor template, copper-platinum binary alloy nanotubes with different compositions were prepared by controlling the amount of chloroplatinic acid. The diameter of the nanotubes is between 100-150 nm, the wall thickness is 15-25 nm, the length of the nanotubes is 2-3 渭 m, and the copper and platinum elements are distributed uniformly on the alloy nanotubes. The electrocatalytic properties of copper platinum alloy nanotubes with different compositions were studied. Among them, the composition of Cu40Pt60 has the best catalytic performance. The initial potential and half-wave potential of the catalytic oxygen reduction reaction are higher than commercial Pt/C 57mV and 20mV, respectively. In the process of catalytic methanol oxidation, the ratio of positive and negative sweep peak current density is about 1.57 times of commercial Pt/C. The material alloying effect can greatly improve its electrocatalytic activity. The results of redox reaction show that the electronic structure of Pt 5d orbital is changed due to the effect of copper-platinum alloying in commercial Pt/C, copper-platinum alloys, which weakens the interaction between hydroxide and the surface of the alloy. The rate of electrocatalytic reaction was increased. Secondly, in order to reduce the cost of the binary alloy, palladium chloride was used to replace chloroplatinic acid, and copper alloy nanotubes were prepared by the same electrochemical replacement method. The results showed that the catalyst exhibited excellent catalytic performance of methanol oxidation, and most of the catalysts showed better catalytic performance than commercial Pt/C.. In order to further investigate the effect of alloying effect on catalytic performance, copper platinum-palladium ternary alloy nanotubes were prepared on the basis of the above binary alloys. In the ternary alloy nanotubes, all metal elements are uniformly distributed on the wall of the alloy nanotubes, and the alloying degree reaches the atomic level. The ternary alloys have excellent catalytic performance due to the synergistic effect between metals. The catalytic oxygen reduction performance of ternary alloys with different composition is superior to commercial Pt/C,. The best performance of Cu28.5Pt37.2Pd34.3, is that the initial potential and half wave potential of Cu28.5Pt37.2Pd34.3, in acid system are higher than commercial Pt/C 88mV and 49mV respectively. At the potential value of 0.85 V (vs.RHE), the kinetic current density of catalytic oxygen reduction is about 8 times that of commercial Pt/C. In addition, the ratio of positive and negative peak current density of methanol oxidation is about 1. 9 times that of commercial Pt/C. Finally, by comparing the performance of three kinds of alloy catalysts, the catalytic activity from strong to weak is as follows: copper-platinum-palladium ternary alloy copper-platinum binary alloy copper-palladium binary alloy. The high alloying of ternary alloys is one of the reasons for the high electrocatalytic properties of oxygen reduction and methanol oxidation.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36
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