Morphology and Surface Reconstruction-Driven Catalytic Enhancement in CoMn₂O₄ for Efficient OER Application

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient and durable oxygen evolution reaction (OER) catalysts are crucial for alkaline water electrolysis.
• Earth-abundant materials are sought after to reduce the cost of electrolysis.

Purpose of the Study:

• To develop and investigate nanograss-like CoMn2O4 electrode films for efficient OER in alkaline media.
• To explore the effect of synthesis temperature on the OER performance and durability of CoMn2O4 catalysts.

Main Methods:

• Direct growth of nanograss-like CoMn2O4 films on stainless-steel substrates using a temperature-controlled hydrothermal approach.
• Systematic investigation of OER performance in 1.0 M KOH, including overpotential measurements at various current densities.
• Durability testing of the optimized catalyst over 100 hours.

Main Results:

• CoMn2O4 synthesized at 120 °C (CMO-120) exhibited the best OER activity, requiring a low overpotential of 292 mV at 10 mA cm⁻².
• CMO-120 demonstrated exceptional performance at high current densities (434 mV at 300 mA cm⁻²), outperforming catalysts synthesized at other temperatures.
• The enhanced activity is linked to the interconnected nanograss architecture, mixed Co/Mn redox states, and abundant defect-related oxygen species, improving surface area and charge transport.
• CMO-120 showed excellent durability over 100 hours post-activation.

Conclusions:

• Precise temperature regulation during synthesis is an effective strategy for optimizing Mn-Co spinel catalysts for alkaline OER.
• The developed nanograss-like CoMn2O4 presents a promising earth-abundant catalyst for efficient and durable alkaline water electrolysis.