Advanced Electrochemical System for Energy Storage through CO₂ conversion

The extensive usage of fossil fuel as energy source has led to the increased atmospheric concentration of CO₂, which is mainly responsible for the negatively intensified greenhouse effect upon our living habitat. Various pathways have been studied in order to alleviate the negative effects of CO₂ emission; electrochemical reduction of CO₂ is considered as one of the promising method to effectively reduce CO₂ emission. The process involves the conversion of CO₂ to useful chemicals and fuels using high temperature solid oxide electrolysis cells (SOECs), these devices can run in the opposite direction in solid oxide fuel cells but utilize similar concepts, and involve materials challenges and operating conditions to achieve 'Power to Fuels'. It is well known that CO₂ molecules are very stable so that high energy input is required for cathodic reaction to proceed. The cathodic reaction, therefore, plays a vital role in the overall cell performance and so far, extensive investigations have been conducted to develop the advanced cathode materials with high catalytic activity and stability.

Among various types of catalysts for SOECs, perovskite-based materials have attracted world wide research efforts as the mixed ionic and electronic conductors through introducing proper doping elements into perovskite lattice during synthesis process. Nonetheless, the cathodic material thus developed still suffer from relatively lower catalytic activity compared to conventional nickel-based cermets. In this work, three strategies are adopted to improve their performance of CO₂ electrochemical reduction. It has been demonstrated that the perovskites with exsolved nanoparticles anchored on the surface of matrix exhibit excellent catalytic activity in comparison with the conventional ones. As a facile in-situ process, exsolution can significantly increase the number of reaction sites by forming uniformly dispersed active nanoparticles and at the same time, can efficiently impede agglomeration of nanoparticles under high temperature. Therefore, the perovskite with exsolved nanoparticles is a promising cathode material that can enhance the overall performance of CO₂ reduction in an electrochemical cell.