Evaluation and Enhancement of the Oxygen Reduction Reaction Activity on Hafnium Oxide Nanoparticles Assisted by L(+)-lysine
Evaluation and Enhancement of the Oxygen Reduction Reaction Activity on Hafnium Oxide Nanoparticles Assisted by L(+)-lysine
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DOI：
10.1016/j.electacta.2015.10.184
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发表时间：
2016-05
影响因子：
6.6
通讯作者：
M. Chisaka;N. Itagaki
中科院分区：
文献类型：
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作者：
M. Chisaka;N. Itagaki
由于氧化物的绝缘性质，评估氧化物的氧还原反应（ORR）很困难。在本研究中，将不同量的L(+)-赖氨酸添加到前驱体分散体中，用于在还原氧化石墨烯片(HfOx-rGO)上水热合成氧化铪纳米粒子，以在HfOx催化剂上涂覆碳层，从而增加电导率和活性位点数量。循环伏安法表明，当L(+)-赖氨酸与GO,R的质量比大于26时，形成碳层，并且碳层的数量随着R的增加而单调增加。 X射线光电子能谱和旋转盘电极分析表明，热解产生ORR活性氧缺陷，其形成被认为涉及碳热还原。当 53 ≤ R ≤ 210 时，HfOx–rGO 含有相似数量的氧缺陷和 ORR 活性，如 0.1 mol dm−3H2SO4 中的可逆氢电极的起始电位为 0.9 V 所示。然而，活性位点的数量取决于R，因为L(+)-赖氨酸衍生的碳层的数量增加了活性位点的数量和对氧扩散的电阻率。
Evaluation of the oxygen reduction reaction (ORR) on oxide compounds is difficult owing to the insulating nature of oxides. In this study, various amounts of L(+)-lysine were added to the precursor dispersion for the hydrothermal synthesis of hafnium oxide nanoparticles on reduced graphene oxide sheets (HfOx–rGO) to coat the HfOxcatalysts with layers of carbon, thereby increasing the conductivity and number of active sites. When the mass ratio of L(+)-lysine to GO,R, was above 26, carbon layers were formed and the amount monotonically increased with increasingR, as noted by cyclic voltammogrametry. X-ray photoelectron spectroscopy and rotating disk electrode analyses revealed that pyrolysis produced ORR-active oxygen defects, whose formation was proposed to involve carbothermal reduction. When 53 ≤R≤ 210, HfOx–rGO contained a similar amount of oxygen defects and ORR activity, as represented by an onset potential of 0.9 V versus the reversible hydrogen electrode in 0.1 mol dm−3H2SO4. However, the number of active sites depended onRdue to the amount of L(+)-lysine-derived carbon layers that increased both the number of active sites and resistivity towards oxygen diffusion.