NiCu合金和聚AMT的电催化析氢性能的研究

发布时间：2018-04-25 22:37

本文选题：析氢反应 + 枝状NiCu纳米晶　；参考：《合肥工业大学》2015年硕士论文

【摘要】：氢能是一种理想的能源载体,具有无污染、能量密度高、可实现各类能源的能量转移等优点。电解水可制得高纯度氢气,但因能源消耗大,大规模的实际生产应用受到了很大限制,需要通过开发高催化活性的电极材料来降低析氢过电势。本论文中,在不同基底电极表面分别修饰镍铜纳米合金和2-氨基-5-巯基-1,3,4-噻二唑(AMT),研究两种材料对析氢反应的电催化活性。通过恒电流法在铜基底表面沉积不同原子比的NiCu合金,并测试其在硫酸介质中的催化析氢性能。采用场发射扫描电子显微镜(FE-SEM)和能谱(EDX)技术对合金层的表面形貌和组成进行分析表征,结果表明,所沉积的NiCu合金组成与采用的电流密度直接相关,当电流密度为50 mA cm-2时,NiCu原子比为1:1,呈枝晶状的纳米珍珠链紧密排列。利用线性极化法对析氢电催化活性进行评价,NiCu原子比为1:1时活性最强,交换电流密度比Cu电极提高2836倍,析氢超电势(η50)降低265 mV;比纯Ni的Cu基电极的交换电流密度提高8.5倍,析氢超电势(η50)降低135 mV。由交流阻抗图谱和计时电势数据可知,NiCu纳米合金能显著降低析氢反应的电荷传递电阻,有利于提高活性氢从活性位点的脱附能力。综合分析可知,枝状NiCu纳米晶是具有优越电催化活性的非贵金属析氢催化剂。采用多圈循环扫描伏安法在玻碳电极表面电氧化AMT形成导电聚合物PAMT,并测试其在酸性电解液中的催化析氢性能。对制备的电极材料进行FE-SEM和XPS表征,PAMT薄膜表面均匀致密,表面呈褶皱的短丝状形貌(长度小于100 nm)。经Tafel曲线分析可知,PAMT催化剂使电极开路电势正移约313mV,析氢活化能显著降低；由交流阻抗图谱和计时电势法可以看出,PAMT膜不仅能降低析氢反应的电荷传递电阻,还能有效加快氢原子从电极活性位点的脱除过程。在PAMT薄膜上的析氢活性位可用—N=来表示,其成对出现可满足H-H结合所需。上述分析表明,富含氮、硫原子的导电聚合物作为析氢电催化剂具有广阔的发展前景。不同的基底材料对电催化体系的影响作用不同。为考察不同碳基底电极对修饰PAMT导电聚合物薄膜的析氢性能影响,同样在sCPE电极表面电聚合PAMT薄膜。对比PAMT/sCPE和PAMT/GCE电极在酸性介质下的催化析氢活性,经过比较,在不同基底电极上修饰PAMT薄膜的最佳聚合圈数存在差异；在碳糊电极的最佳聚合圈数为100,而玻碳电极的聚合圈数在60时达到最佳析氢活性,且PAMT/sCPE薄膜电极的交换电流密度是sCPE电极的647倍,活化能提高65%1而PAMT/GCE电极是GCE电极的533倍,活化能提高48%。从上述实验数据分析可知,sCPE基底电极的析氢催化活性在一定程度上要优于GCE电极。
[Abstract]:Hydrogen energy is an ideal energy carrier, which has the advantages of no pollution, high energy density and can realize energy transfer of all kinds of energy. Electrolytic water can produce high purity hydrogen, but because of the large energy consumption, the application of large-scale practical production is greatly limited, it is necessary to develop high catalytic activity electrode materials to reduce the potential of hydrogen evolution. In this paper, the electrocatalytic activity of nickel copper nanoalloy and 2-amino-5-mercaptol 3-thiadiazole-4-thiadiazolium on the surface of different substrate electrodes for hydrogen evolution was studied. NiCu alloys with different atomic ratios were deposited on the surface of copper substrate by constant current method and their catalytic hydrogen evolution properties in sulfuric acid medium were tested. The surface morphology and composition of the alloy layer were characterized by FE-SEM and EDX techniques. The results show that the composition of the deposited NiCu alloy is directly related to the current density. When the current density is 50 Ma cm-2, the atomic ratio of Ni Cu is 1: 1, and the nanocrystalline pearl chains are arranged tightly. The electrocatalytic activity of hydrogen evolution was evaluated by linear polarization method. The activity of NiCu atom was strongest at 1:1, the exchange current density was 2836 times higher than that of Cu electrode, the superpotential of hydrogen evolution (畏 50) was decreased by 265 MV, and the exchange current density of Ni based electrode was 8.5 times higher than that of pure Ni based electrode. The superpotential of hydrogen evolution (畏 50) is reduced by 135 MV. The electrochemical impedance spectra and chronopotentiometry data show that NiCu nanocrystalline alloy can significantly reduce the charge transfer resistance of hydrogen evolution reaction and improve the desorption ability of active hydrogen from the active site. Comprehensive analysis shows that dendritic NiCu nanocrystals are non-noble metal hydrogen evolution catalysts with superior electrocatalytic activity. AMT was electrooxidized on the surface of glassy carbon electrode by multi-loop cyclic scanning voltammetry to form a conductive polymer, PAMT.The catalytic hydrogen evolution of PAMTs in acidic electrolyte was tested. The prepared electrode materials were characterized by FE-SEM and XPS. The surface of the films was uniform and compact, and the surface of the films was pleated with short filaments (length less than 100nm). According to the analysis of Tafel curves, the open circuit potential of the electrode was positively shifted to about 313mV, and the activation energy of hydrogen evolution was significantly decreased, and the electrochemical impedance diagram and chronopotentiometry showed that the PAMT film could not only reduce the charge transfer resistance of hydrogen evolution reaction, but also decrease the charge transfer resistance of hydrogen evolution reaction. It can also accelerate the removal of hydrogen atoms from the active sites of the electrode. The active sites of hydrogen evolution on PAMT thin films can be represented by -N =, and the pair can meet the needs of H-H binding. The results show that the electrically conductive polymers rich in nitrogen and sulfur atoms are promising as electrocatalysts for hydrogen evolution. The effect of different substrate materials on the electrocatalytic system is different. In order to investigate the effect of different carbon substrate electrodes on the hydrogen evolution properties of modified PAMT conductive polymer films, PAMT films were also electropolymerized on the surface of sCPE electrodes. By comparing the catalytic hydrogen evolution activity of PAMT/sCPE and PAMT/GCE electrodes in acid medium, the optimum number of polymerization cycles for modified PAMT films on different substrate electrodes is different. The optimum polymerization cycle number of carbon paste electrode is 100, while the polymerization cycle number of glassy carbon electrode is 60. The exchange current density of PAMT/sCPE thin film electrode is 647 times that of sCPE electrode, and the activation energy of PAMT/GCE electrode is 533 times that of GCE electrode. Activation energy increases by 48. According to the above experimental data, the catalytic activity of the substrate electrode for hydrogen evolution is better than that of the GCE electrode to some extent.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2;O643.36

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