Electrochemical conversion of methane measured by anode out gas monitoring over Ce-Co-Cu anode electrocatalysts

Solid oxide fuel cells (SOFCs) enable the highly efficient conversion of fuels to electricity, offering notable fuel flexibility. However, conventional nickel-based SOFC anode materials currently available on the market are unable to effectively utilise low-carbon fuels without succumbing to carbon deposition, which degrades the anode rapidly. This study introduces a nickel-free SOFC anode electrocatalyst capable of achieving impressive power densities exceeding 400 mW·cm^-2 at 850˚C when operating directly with pure methane. Comparative analysis of three cell types, each with varying amounts of ceria, cobalt, and copper in their anode compositions, was conducted. Gas chromatography was employed to monitor anode effluent gases under electrochemical conditions, complemented by electrochemical impedance assessments using hydrogen as the fuel to identify polarisation sources within these innovative anode configurations.

The findings reveal that tracking chemical and electrochemical reactions in SOFCs provides insights into efficiency and fuel conversion mechanisms, wherein the anode material transforms fuel into useful products while generating electricity and heat. Notably, copper additions influence these behaviours, although Cobalt-rich catalysts exhibit superior performance in facilitating fuel conversion through combined electrochemical and thermochemical reactions. Distribution of relaxation times analysis highlights the necessity of optimising microstructure and mitigating gas diffusion polarisation effects, corroborating the validity of equivalent circuit models aligned with electrochemical impedance spectroscopy data.