Co nanoparticles decorated with in-situ exsolved oxygen-storage CeO2 for an efficient and stable electrolysis of pure CO2

The valorization of the CO2 greenhouse gas is important in decarbonization using the renewable energies. Intermediate temperature solid oxide electrolysis cells (SOEC) working at around 800 degrees C can be useful in activating the strong C--O bond (799 kJ mol-1) in CO2 for the production of CO and decreasing the precious electricity by partially using the heat instead. Ceria/Co doping on the stable chromite is employed to design a composite oxide/metal cathode with a unique ceria decorating Co0 for the direct CO2 electrolysis. The in situ outgrowth of Co0 from the B site activates the ceria exsolution from the A site, or vice versa, producing a well-adhered heterojunction for the activation of CO2. A high current and stable density above 1 Acm- 2 for 300 h is obtained at a bias of 1.3 V for the CO2 at a Faraday efficiency close to unity. The higher electrochemical performance of the cell with Ce/Co0 codoped cathode is explained by the oxygen storage property of the ceria rather than the direct activation of CO2 over ceria. This work presents a novel method of constructing metal/oxide cathode for efficient CO2 analysis and in-depth mechanistic explanation for the metal/oxide hetero-structure in CO2 activation.

Automated summary

The valorization of CO2 greenhouse gas is important in decarbonization using renewable energies. Intermediate temperature solid oxide electrolysis cells (SOEC) can activate the strong C-O bond in CO2 for the production of CO and decrease electricity consumption. In this study, a composite oxide/metal cathode with ceria/Co doping on stable chromite is designed for direct CO2 electrolysis. The unique heterojunction structure formed by ceria exsolution and Co0 outgrowth from the B site enables efficient CO2 activation and high electrochemical performance.