Designing a Glycerol Oxidation Electrocatalyst through Active Site Identification and Optimisation in Co₃O₄.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Identifying active sites in electrocatalysts like Co₃O₄ is crucial for improving glycerol oxidation reaction (GOR) performance.
• The precise role of cobalt coordination environments in Co₃O₄'s GOR activity remains unclear.

Purpose of the Study:

• To systematically investigate the influence of cobalt coordination on GOR activity in spinel catalysts.
• To elucidate the specific cobalt sites responsible for GOR in Co₃O₄.
• To design and synthesize an enhanced electrocatalyst for GOR based on structure-activity insights.

Main Methods:

• Synthesis of spinel catalysts (Co₃O₄, MgCo₂O₄, CoAl₂O₄) to vary cobalt coordination.
• Electrochemical characterization of glycerol oxidation reaction (GOR) performance.
• Fabrication of a novel CuCo₂O₄/NF catalyst via cation substitution.

Main Results:

• GOR activity is critically dependent on the geometric coordination of cobalt sites.
• Octahedral Co³⁺Oh sites are the primary active sites for GOR, not tetrahedral Co²⁺Td sites.
• The developed CuCo₂O₄/NF catalyst shows excellent GOR performance (10 mA cm⁻² at 1.16 V vs RHE) and stability (>120 h).
• High Faradaic efficiency (98.04%) for formic acid conversion was achieved with CuCo₂O₄/NF at 1.40 V vs RHE.

Conclusions:

• Clarified the structure-activity relationship between cobalt coordination and GOR activity in Co₃O₄.
• Demonstrated that substituting tetrahedral Co²⁺Td sites with Cu²⁺ enhances intrinsic activity of octahedral Co³⁺Oh sites.
• Provided a strategy for designing robust and stable spinel electrocatalysts for GOR.