Efficient nanointerface hybridization in a nickel/cobalt oxide nanorod bundle structure for urea electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Urea electrolysis is crucial for energy applications.
• Efficient nanostructured catalysts are needed to improve urea oxidation kinetics.
• The valence state of Ni in Ni/Co oxide nanostructures influences catalytic performance.

Purpose of the Study:

• To investigate the correlation between Ni valence states and catalytic capability in hybrid Ni/Co oxide nanorods for urea oxidation.
• To understand the synergistic effects in Ni/Co oxide nanostructures for enhanced electrocatalysis.
• To evaluate the performance of Ni/Co oxide catalysts in urea-assisted water electrolysis for hydrogen production.

Main Methods:

• Synthesis of hybrid Ni/Co oxide nanorods with specific nanostructure assembly.
• Characterization of crystal lattice hybridization and valence states (Ni2+/Ni3+) at the Ni/Co oxide interface.
• Electrochemical testing to determine catalytic activity, selectivity, and onset potentials for urea oxidation and water oxidation.

Main Results:

• Crystal lattice hybridization observed at the interface of Ni/Co oxide nanoparticles within nanorod bundles.
• An optimal Ni2+/Ni3+ ratio in Ni/Co oxide demonstrated the highest catalytic ability due to synergistic effects and high valence Ni species.
• Achieved low onset potential (1.29 V) for urea oxidation versus water oxidation (1.52 V), with high selectivity below 1.50 V.
• Demonstrated energy efficiency for hydrogen evolution in urea-assisted water electrolysis, requiring 190 mV less potential for 10 mA cm-2.

Conclusions:

• The valence state of Ni, specifically the Ni2+/Ni3+ ratio, is critical for optimizing the catalytic performance of Ni/Co oxide nanorods.
• Synergistic effects between Ni and Co oxides, driven by optimal Ni valence states, significantly enhance urea oxidation kinetics.
• Ni/Co oxide nanostructures show great promise for energy-efficient hydrogen production through urea-assisted water electrolysis.