Three-dimensional Ni₄O₄-cubane metal-organic framework as a high-performance electrocatalyst for urea oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is a bottleneck in overall water-splitting due to its sluggish kinetics.
• The urea oxidation reaction (UOR) presents a more efficient alternative for water-splitting applications.
• Developing efficient electrocatalysts is crucial for advancing water-splitting technologies.

Purpose of the Study:

• To investigate a novel three-dimensional (3D) nickel-containing metal-organic framework (MOF 1) as an electrocatalyst for the urea oxidation reaction (UOR).
• To evaluate the catalytic activity, efficiency, and stability of MOF 1 for UOR.
• To explore the potential of MOF 1 in energy conversion processes and addressing urea contamination.

Main Methods:

• Synthesis and characterization of a 3D nickel-containing metal-organic framework (MOF 1).
• Electrochemical evaluation of MOF 1 for the urea oxidation reaction (UOR), including onset potential and Tafel slope measurements.
• Stability testing using controlled potential electrolysis and characterization via powder X-ray diffraction and X-ray photoelectron spectroscopy.

Main Results:

• MOF 1 exhibited a low onset potential of 1.18 V for UOR in KOH (1 M) and urea (0.33 M).
• The catalyst achieved a low overpotential of 1.24 V at a current density of 10 mA cm⁻².
• MOF 1 demonstrated excellent physicochemical stability over a 17-hour electrolysis test.
• The material showed a low Tafel slope of 38.8 mV dec⁻¹, indicating efficient catalytic kinetics for UOR.

Conclusions:

• The 3D nickel-containing MOF 1 is a highly efficient and robust electrocatalyst for the urea oxidation reaction (UOR).
• MOF 1 offers a promising alternative to the oxygen evolution reaction (OER) in water-splitting, with lower overpotentials and improved kinetics.
• This work highlights the potential of MOF 1 for energy conversion and mitigating urea contamination issues.