Co-Enriched High Entropy Oxides for Efficient Continuous Electrochemical Methane Conversion: Catalytic Performance...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Traditional thermochemical syngas production is energy-intensive and relies on fossil fuels.
• Electrochemical conversion of methane presents a sustainable alternative pathway.
• Developing efficient catalysts for methane electroconversion remains a key challenge.

Purpose of the Study:

• To explore high-entropy oxide (HEO) catalysts for electrochemical methane conversion.
• To identify specific elemental compositions within HEOs that enhance catalytic activity.
• To assess the economic and environmental viability of the developed catalytic process.

Main Methods:

• Synthesis and characterization of a multi-element high-entropy oxide (Co, Cr, Fe, Mn, Ni).
• Electrochemical testing of the HEO catalyst for methane-to-ethanol conversion at room temperature.
• Analysis of catalyst properties using projected density of states (PDOS) to understand methane activation mechanisms.
• Long-term stability testing in a flow cell electrolyzer.
• Process modeling for economic and environmental impact assessment.

Main Results:

• A cobalt-rich HEO catalyst demonstrated high efficiency for room-temperature electrochemical methane conversion.
• PDOS analysis indicated that cobalt sites have an optimal p-band center for methane activation.
• The Co-rich HEO catalyst achieved an ethanol production rate of 12315 µmol/gcat/hr with 63.5% Faradaic efficiency at 1.6 VRHE.
• Continuous methane-to-ethanol conversion was achieved at 26533 µmol/gcat/hr over 100 hours in a flow cell.
• Process modeling suggested commercial viability and significant CO₂ emission reduction.

Conclusions:

• Cobalt-rich high-entropy oxides are highly effective catalysts for electrochemical methane conversion to ethanol.
• The catalyst's performance is linked to the electronic structure of cobalt sites, facilitating methane activation.
• The developed process offers a sustainable, economically feasible, and environmentally beneficial alternative to conventional methods.