1. Nitrogen dopants in nickel nanoparticles embedded carbon nanotubes promote overall urea oxidation.
- Author
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Zhang, Quan, Kazim, Farhad MD., Ma, Shuangxiu, Qu, Konggang, Li, Min, Wang, Yangang, Hu, Hao, Cai, Weiwei, and Yang, Zehui
- Subjects
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HYDROGEN evolution reactions , *CARBON nanotubes , *NITROGEN , *UREA , *CATALYST poisoning , *DOPING agents (Chemistry) , *NICKEL - Abstract
• Nitrogen atoms in Ni@NCNT facilitate the in-situ conversion of metallic Ni to Ni3+ species. • Nitrogen atoms in Ni@NCNT weaken the interaction between Ni3+ and CO 2 in urea oxidation. • 1.56 V is required to achieve 10 mA cm−2 in overall urea oxidation for Ni@NCNT. Urea electro-oxidation is an attractive and alternative anodic reaction in the electrochemical generation of hydrogen using wastewater ascribing to the low theoretical voltage and non-precious metal (nickel) catalyst for urea oxidation reaction (UOR); however, the sluggish UOR and poisoning of catalyst impede the practical application. Here, in this work, we synthesize a series of nickel nanoparticles embedded nitrogen doped carbon nanotubes (Ni@NCNT) and study the effect of nitrogen dopants on UOR catalytic activity. The nitrogen dopants can weaken the binding strength between CO 2 species and active sites resulting in alleviation of CO 2 poisoning; simultaneously, nitrogen dopants also promote the in-situ conversion of Ni3+ species facilitating UOR catalysis; as a result, electrocatalytic current density of 45.8 mA cm−2 is recorded for Ni@NCNT in 1 M KOH electrolyte with 0.5 M urea at 1.5 V vs. RHE, which is 3.8 fold better than commercial Pt/C (11.8 mA cm−2). Moreover, Ni@NCNT, due to the more nitrogen dopants, exhibits a comparable overpotential to commercial Pt/C for driving hydrogen evolution reaction (HER) catalysis in 1 M KOH electrolyte at high current density (400 mA cm−2). Subsequently, 1.56 V is demanded for overall UOR catalysis on Ni@NCNT with current density of 10 mA cm−2. This work offers useful information for designing a stable and efficient electrocatalyst for not only UOR but also electrochemical generation of H 2 from wastewater. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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