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An Unveiled Electrocatalysis Essence of NiCo Hydroxides through in Situ Raman Spectroscopy for Urea Oxidation
Energy Technology ( IF 3.6 ) Pub Date : 2022-02-16 , DOI: 10.1002/ente.202101010
Xu Yang 1 , Huimin Zhang 2 , Binbin Yu 3 , Yan Liu 4 , Wei Xu 1 , Zucheng Wu 1
Affiliation  

The electrochemical urea oxidation reaction (UOR) is the performance-limiting half reaction of urea electrolysis for producing renewable hydrogen energy. Nevertheless, the essence of electrode function mechanism of catalysts remains unclear. Therefore, design and optimization of catalysts are restricted. Herein, an in situ Raman spectroscopy method is employed to directly measure the electrode properties of the NiCo double hydroxides (NiCo DHs) under working conditions. Given definitely evidence, the evolution process of in situ Raman spectra shows that the Ni element is converted to NiOOH under UOR potentials, while the Co dopant is converted to CoOOH and further to higher-valence CoO2 species. Obviously, the catalytically active phase toward UOR is really a complex NiOOH–CoOOH–CoO2 phase. Accurately matched spectral wavenumbers and electrochemical measurements of the catalytic electrodes explicitly reveal that the addition of Co assuredly reduces the onset potential for electroactive NiOOH formation. The Raman results also indicate effects of the NiO bond elongation and increased disorder caused by Co doping. Herein, an important understanding and new mechanistic perspectives for the electrode reaction process of UOR with NiCo binary catalysts are provided.

中文翻译:

通过原位拉曼光谱揭示了 NiCo 氢氧化物电催化尿素氧化的本质

电化学尿素氧化反应(UOR)是尿素电解产生可再生氢能的性能限制半反应。然而,催化剂的电极功能机理的本质仍不清楚。因此,催化剂的设计和优化受到限制。本文采用原位拉曼光谱法直接测量工作条件下镍钴双氢氧化物(NiCo DHs)的电极性能。鉴于确凿的证据,原位拉曼光谱的演变过程表明,在 UOR 电位下,Ni 元素转化为 NiOOH,而 Co 掺杂剂转化为 CoOOH 并进一步转化为更高价的 CoO 2物种。显然,对 UOR 的催化活性相实际上是一个复杂的 NiOOH–CoOOH–CoO 2阶段。精确匹配的光谱波数和催化电极的电化学测量明确表明,添加 Co 确实降低了电活性 NiOOH 形成的起始电位。拉曼结果还表明了 Ni O 键伸长和 Co 掺杂引起的无序度增加的影响。在此,为 UOR 与 NiCo 二元催化剂的电极反应过程提供了重要的理解和新的机理观点。
更新日期:2022-02-16
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