Investigation of Electrocatalytic CO₂ Reduction Reaction Mechanism: Role of H₂s and Exsolved Metal Nanoparticle at Perovskite Oxides Electrodes

ABSTRACT Affordable and sustainable energy demands from post-modern society as well as the need to lower the CO 2 emissions require alternative approaches rather than business-as-usual [1] . Solid oxide fuel cells (SOFC) and solid oxide electrolysis cells (SOEC) are one of the promising technologies that are being developed to meet these needs. The working principle of an SOEC is based on heterogeneous electrocatalysis to produce syngas (CO and H 2 ) by splitting CO 2 and H 2 O at high temperatures. The stability and electrochemical performance of the components, including the solid-state electrolyte and the electrode materials, are vital to making this technology mature enough to enhance its economic competitiveness [2] . Therefore, the physical and chemical features of the components need to be understood fundamentally. Due to its high electrocatalytic activity, Ni-YSZ cermets are still the most commonly used electrode materials in SOECs. However, the poisoning of these catalysts by sulfur deposition and coke formation is a problem. As a result, there has been growing interest in using mixed conducting perovskites oxides (MIECS) as electrode materials, which are more resistant to these challenges and as their chemical and physical properties can be easily tailored [3] . Here, we investigate a family of MIECS that can be used in many fuel environments and is also highly active in air, namely LCFCr (La 0.3 Ca 0.7 Fe 0.7 Cr 0.3 O 3-δ ). One specific objective of the current study is to elucidate the CO 2 reduction mechanism based on varying the composition of LCFCr [4,5] as well as by alterations of the operating conditions, such as temperature, reactant gas mixture, and applied potential. Importantly, the effect of the presence of H 2 S in the gas phase [6] and ex-solved metal nanoparticles on the surface [7] during exposure to CO 2 at open circuit and under CO 2 reduction conditions is being investigated. This work involves the use of reactive molecular dynamics (ReaxFF MD), electrochemical perturbations, and thermo-catalytic methods, with our initial ReaxFF MD results showing good agreement with the experimental results [8] . ACKNOWLEDGMENTS This computational research was supported by the Canada First Research Excellence Fund (CFREF), while the platforms for this computational work were provided by Westgrid (https://www.westgrid.ca) and Compute Canada (https://www.computecanada.ca). Thanks are also extended to Dr. Haris Ansari, Oliver Calderon, Michael Pidburtnyi, Dr. Scott Paulson, Dr. Anand Singh, Sara Bouzidi and Adam Bass for helpful discussions.