Electrocatalytic Methane Oxidation Greatly Promoted by Chlorine Intermediates

Area of Science:

• Catalysis
• Electrochemistry
• Materials Science

Background:

• Methane (CH4) conversion at ambient conditions is challenging due to its inert C-H bond.
• Selective activation of CH4 without over-oxidation is crucial for producing value-added chemicals.

Purpose of the Study:

• To develop an efficient and selective method for methane conversion at room temperature.
• To utilize electrochemically generated intermediate chlorine species (*Cl) for CH4 activation.
• To investigate mixed cobalt-nickel spinels as electrocatalysts for this process.

Main Methods:

• Electrochemical generation and stabilization of intermediate chlorine species (*Cl) on mixed cobalt-nickel spinels.
• Tuning Co/Ni ratios in spinel catalysts to optimize performance.
• Characterization of catalyst properties and reaction mechanisms.

Main Results:

• The CoNi2Ox electrocatalyst demonstrated high CH3Cl yield (364 mmol g-1 h-1) and selectivity (>400) at room temperature.
• Lower overpotentials for *Cl formation facilitated effective CH4 activation and conversion to CH3Cl.
• Ni3+ at octahedral sites stabilized surface-bound *Cl species, preventing over-oxidation to CO2.
• Successful CH4 conversion demonstrated under seawater conditions.

Conclusions:

• Mixed cobalt-nickel spinels efficiently catalyze methane conversion to methyl chloride (CH3Cl) at room temperature using electrochemically generated chlorine species.
• The developed electrocatalytic system offers a promising route for sustainable methane valorization.
• The process shows potential for application under challenging conditions, including seawater environments.