Enhanced CO₂ Electrolysis Through Mn Substitution Coupled with Ni Exsolution in Lanthanum Calcium Titanate Electrodes

In this study, perovskite oxides La_0.3Ca_0.6Ni_0.05Mn_xTi_{0.95- x}O_{3- γ} (x = 0, 0.05, 0.10) are investigated as potential solid oxide electrolysis cell cathode materials. The catalytic activity of these cathodes toward CO₂ reduction reaction is significantly enhanced through the exsolution of highly active Ni nanoparticles, driven by applying a current of 1.2 A in 97% CO₂ - 3% H₂O. The performance of La_0.3Ca_0.6Ni_0.05Ti_0.95O_3-γ is notably improved by co-doping with Mn. Mn dopants enhance the reducibility of Ni, a crucial factor in promoting the in situ exsolution of metallic nanocatalysts in perovskite (ABO₃) structures. This improvement is attributed to Mn dopants enabling more flexible coordination, resulting in higher oxygen vacancy concentration, and facilitating oxygen ion migration. Consequently, a higher density of Ni nanoparticles is formed. These oxygen vacancies also improve the adsorption, desorption, and dissociation of CO₂ molecules. The dual doping strategy provides enhanced performance without degradation observed after 133 h of high-temperature operation, suggesting a reliable cathode material for CO₂ electrolysis.