Urea oxidation electrocatalysis on nickel hydroxide: the role of disorder
JOURNAL OF SOLID STATE ELECTROCHEMISTRY(2020)
摘要
The urea oxidation reaction (UOR) is an important challenge in electrocatalysis, in the context of electrolyzers, fuel cells, medical sensing, and bio-waste treatment. The leading electrocatalysts for the UOR are nickel hydroxide surfaces, operating by the Botte mechanism: Ni II (OH) 2 is oxidized to Ni III OOH, and the latter drives the UOR. However, these materials have several polymorphs, with α- and β-Ni(OH) 2 , and γ- and β-NiOOH, as described by the Bode diagram. We now report a systematic study of a series of nickel hydroxides, varying gradually from α-rich to β-rich materials. The crystallinity, order, hydration, intercalation, and morphology of these materials have been characterized by XRD, Raman, ATR-FTIR, XPS, and HRSEM and linked to their electrochemical activity. The disordered α phase was found to be superior to the β phase as a UOR electrocatalyst, with an oxidation onset potential of 0.31 V vs. SCE, better reversibility, and higher anodic current densities. Moreover, the perfect match in onset potentials between UOR electrocatalysis and the Ni 2+ /Ni 3+ oxidation was observed for both phases, suggesting that the Botte mechanism is true for both the α-Ni(OH) 2 /γ-NiOOH couple and the β-Ni(OH) 2 /β-NiOOH couple. We further characterize the dynamic behavior of these materials (activation and aging), allowing us to propose a unified Botte-Bode diagram of UOR on Ni(OH) 2 /NiOOH.
更多查看译文
关键词
Urea oxidation,Nickel hydroxide,Crystallinity,Disorder,Electrocatalysis
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要