Bifunctional Al-Doped Cobalt Ferrocyanide Nanocube Array for Energy-Saving Hydrogen Production via Urea Electrolysis

The very slow anodic oxygen evolution reaction (OER) greatly limits the development of large-scale hydrogen production via water electrolysis. By replacing OER with an easier urea oxidation reaction (UOR), developing an HER/UOR coupling electrolysis system for hydrogen production could save a signif...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2023-10, Vol.28 (20), p.7147
Main Authors: Gao, Xiafei, Gao, Mengyue, Yu, Xueping, Jin, Xiaoyong, Ni, Gang, Peng, Juan
Format: Article
Language:English
Subjects:
Alternative energy
Aluminum
Canada
Cobalt
cobalt ferrocyanide
Crystal structure
Cyanides
Electrolytes
electronic structure
Electrons
Energy conservation
Energy consumption
Energy management systems
Energy use
energy-saving
Hydrogen
Hydrogen production
Iron compounds
Microscopy
Morphology
Nanomaterials
Nickel
Oxidation
Spectrum analysis
Urea
urea oxidation
Water pollution
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Summary:The very slow anodic oxygen evolution reaction (OER) greatly limits the development of large-scale hydrogen production via water electrolysis. By replacing OER with an easier urea oxidation reaction (UOR), developing an HER/UOR coupling electrolysis system for hydrogen production could save a significant amount of energy and money. An Al-doped cobalt ferrocyanide (Al-Co2Fe(CN)6) nanocube array was in situ grown on nickel foam (Al-Co2Fe(CN)6/NF). Due to the unique nanocube array structure and regulated electronic structure of Al-Co2Fe(CN)6, the as-prepared Al-Co2Fe(CN)6/NF electrode exhibited outstanding catalytic activities and long-term stability to both UOR and HER. The Al-Co2Fe(CN)6/NF electrode needed potentials of 0.169 V and 1.118 V (vs. a reversible hydrogen electrode) to drive 10 mA cm−2 for HER and UOR, respectively, in alkaline conditions. Applying the Al-Co2Fe(CN)6/NF to a whole-urea electrolysis system, 10 mA cm−2 was achieved at a cell voltage of 1.357 V, which saved 11.2% electricity energy compared to that of traditional water splitting. Density functional theory calculations demonstrated that the boosted UOR activity comes from Co sites with Al-doped electronic environments. This promoted and balanced the adsorption/desorption of the main intermediates in the UOR process. This work indicates that Co-based materials as efficient catalysts have great prospects for application in urea electrolysis systems and are expected to achieve low-cost and energy-saving H2 production.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules28207147