Catalytic effect of Pd-Ni bimetallic catalysts on high-temperature co-electrolysis of steam/CO₂ mixtures

The performance of solid oxide electrolysis cells for high-temperature co-electrolysis of steam/CO₂ mixtures was enhanced by raising the amount of Pd-Ni bimetallic catalysts fabricated inside their fuel-electrode substrate. High-temperature co-electrolysis has been proposed as a promising technology to store renewable electrical energy in the form of chemical energy and convert CO₂ to valuable syngas. To deploy it into energy markets, it is essential to improve its energy storage efficiency and syngas productivity. In this study, the catalytic effect of Pd-Ni bimetallic catalysts on electrochemical performance and CO₂ conversion was examined to meet these needs. Their homogeneous morphology and distribution were obtained by using an advanced infiltration technique. Increasing the amount of Pd-Ni bimetallic catalysts promotes a reverse water gas shift (RWGS) reaction enhancing steam transport toward the functional layer and hence decreasing a concentration overpotential. This raises a limiting current density and reduces an overvoltage imposed on the cells, in particular, at high current density. In addition, the enhanced RWGS reaction kinetics driven by a higher amount of Pd-Ni bimetallic catalysts loadings enables increasing the CO₂ conversion rate and CO concentration in the product stream. These may enhance the energy storage capacity and lowers the energy requirements for high-temperature co-electrolysis.