Metal-organic framework derived bimetal oxide CuCoO₂ as efficient electrocatalyst for the oxygen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are versatile precursors for synthesizing electrocatalysts due to their tunable properties.
• Efficient electrocatalysts are crucial for water splitting, particularly for improving the oxygen evolution reaction (OER).

Purpose of the Study:

• To synthesize hexagonal MOF-derived CuCoO2 (MOF-CCO) nanocrystals using ZIF-67 and Cu-BTC as precursors.
• To investigate the influence of synthesis parameters on the structure and morphology of MOF-CCO.
• To evaluate the OER performance and understand the catalytic mechanism of the synthesized MOF-CCO.

Main Methods:

• One-step solvothermal synthesis using ZIF-67 and Cu-BTC.
• Systematic variation of precursor solvent content, reaction temperature, reactant ratios, NaOH addition, and reactant concentration.
• Electrochemical characterization including overpotential, Tafel slope, and durability tests in 1.0 M KOH.
• X-ray Photoelectron Spectroscopy (XPS) for surface analysis and mechanistic investigation.

Main Results:

• Optimal MOF-CCO nanocrystals (MOF-CCO1) of ~288 nm exhibited excellent OER activity.
• Achieved a low overpotential of 364.7 mV at 10 mA cm-2 and a Tafel slope of 64.1 mV dec-1.
• Demonstrated attractive durability in 1.0 M KOH solution.
• XPS analysis revealed oxygen vacancies, increased surface OH- content, and synergistic redox effects contributing to high catalytic efficiency.

Conclusions:

• The developed one-step solvothermal method successfully produced MOF-CCO nanocrystals with superior OER performance.
• Oxygen vacancies and synergistic effects of redox pairs are key factors for enhanced catalytic activity.
• This work offers a new pathway for synthesizing delafossite nanomaterials for improved water splitting electrocatalysis.