非负载型铜基合金纳米管的制备及其电催化性能的研究

发布时间：2018-11-01 19:16

【摘要】：本文通过电化学置换法,利用铜纳米线作为牺牲模板,通过调节金属盐前驱体种类、浓度以及反应温度制备了高长径比的铜基合金纳米管。重点研究了合金的成分、晶体结构对其电催化的性能的影响规律,为开发非负载型纳米电催化材料提供了基础数据支持。首先,不同合金比例的铜钯合金纳米管,其直径在100nm左右,长度约几微米,壁厚20nm左右。在催化氧气还原反应过程中,不同合金比例铜钯合金纳米管在催化氧气还原反应中Cu45Pd55具有最好的催化活性并且比商业Pt/C更好。根据动力学相关参数的计算,发现Cu45Pd55有着最大的交换电流密度证明了其催化速率最快,具有更好的催化活性。XPS表明Cu的加入引起了Pd 3d轨道结合能的变化。活性提高的原因可以归结于合适的Pd的3d结合能可以提高催化活性。并且在甲醇氧化测试中,Cu45Pd55表现出了优异的催化活性,其质量比活性为商业Pt/C的2.33倍。其活性增强的原因主要是Cu的加入使得Pd失电子,促进了甲醇中C-H键的断裂,并且促进生成了大量的Pd-OHad加快了中间产物的氧化,从而提高了催化活性和抗CO中毒能力。其次,通过加入CuCl的络合剂Na2S2O3证明了在Cu和PdCl2发生的置换反应中反应路径为先生成CuCl,之后CuCl歧化分解生成Cu和Cu2+,由于柯肯达尔效应最终形成了中空管状结构。最后,通过加入Na2S2O3作为添加剂,利用电化学置换法,制备了铜基非晶态合金纳米管,确定其非晶态结构,制备得到的纳米管制直径在100nm左右,长度在几微米,壁厚15nm左右。在甲醇氧化性能测试中,铜铂非晶态合金纳米管具有比晶态的铜铂合金和商业Pt/C更好的催化能力和抗CO毒化能力,CO起始氧化电位比起商业Pt/C负了70mV。甲醇电催化氧化动力学过程的研究结果表明：其活性增强的原因是促进了甲醇的吸附和活化,并且促进了Pt-OHad的生成,加速Pt-COad的氧化,最终提高了催化活性。
[Abstract]:In this paper, copper alloy nanotubes with high aspect ratio were prepared by electrochemical replacement method and copper nanowires as sacrificial templates, by adjusting the type, concentration and reaction temperature of metal salt precursors. The effect of the composition and crystal structure of the alloy on its electrocatalytic performance was studied, which provided the basic data support for the development of unsupported nano-electrocatalytic materials. First of all, the diameter, length and wall thickness of copper-palladium alloy nanotubes with different ratios are about 100nm, several microns and 20nm respectively. In the process of catalytic oxygen reduction, Cu45Pd55 has the best catalytic activity and is better than commercial Pt/C in the process of catalytic oxygen reduction. According to the calculation of the kinetic parameters, it is found that Cu45Pd55 has the highest exchange current density, which proves that it has the fastest catalytic rate and better catalytic activity. XPS indicates that the addition of Cu causes the change of the binding energy of Pd 3D orbital. The reason for the increase of activity can be attributed to the suitable 3D binding energy of Pd can improve the catalytic activity. In methanol oxidation test, Cu45Pd55 showed excellent catalytic activity, and its mass specific activity was 2.33 times that of commercial Pt/C. The main reason for the enhancement of the activity is that the addition of Cu makes Pd lose electrons, promotes the breaking of C-H bond in methanol, and accelerates the formation of a large number of Pd-OHad to accelerate the oxidation of intermediate products, thus enhancing the catalytic activity and the ability of resisting CO poisoning. Secondly, it is proved that the reaction path in the substitution reaction between Cu and PdCl2 is that CuCl, is first formed, then CuCl is decomposed to Cu and Cu2, and finally the hollow tubular structure is formed due to the Kokkendal effect by adding CuCl to the complex agent Na2S2O3. Finally, by adding Na2S2O3 as additive, copper based amorphous alloy nanotubes were prepared by electrochemical replacement method. The amorphous structure of the nanotubes was determined. The nanowire diameter of the nanotubes was about 100nm, the length was several microns and the wall thickness was about 15nm. In methanol oxidation test, Cu-Pt amorphous nanotubes have better catalytic ability and anti-CO toxicity than Cu-Pt alloy and commercial Pt/C. The initial oxidation potential of CO is 70 MV lower than that of commercial Pt/C. The results of kinetic study on methanol electrocatalytic oxidation showed that the reason for the enhancement of methanol activity was that it promoted the adsorption and activation of methanol, promoted the formation of Pt-OHad, accelerated the oxidation of Pt-COad, and finally enhanced the catalytic activity.
【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】：TB383.1;O643.36

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