Tuning exsolution of nanoparticles in defect engineered layered perovskite oxides for efficient CO₂ electrolysis

Solid oxide electrolysis cell (SOEC) could be a potential technology to afford chemical storage of renewable electricity by converting water and carbon dioxide. In this work, we present the Ni-doped layered perovskite oxides, (La₄Sr_n−4)_0.9Ti_0.9nNi_0.1nO_3n+2 with n = 5, 8, and 12 (LSTNn) for application as catalysts of CO₂ electrolysis with the exsolution of Ni nanoparticles through a simple in-situ growth method. It is found that the density, size, and distribution of exsolved Ni nanoparticles are determined by the number of n in LSTNn due to the different stack structures of TiO₆ octahedra along the c axis. The Ni doping in LSTNn significantly improved the electrochemical activity by increasing oxygen vacancies, and the Ni metallic nanoparticles afford much more active sites. The results show that LSTNn cathodes can successfully be manipulated the activity by controlling both the n number and Ni exsolution. Among these LSTNn (n = 5, 8, and 12), LSTN8 renders a higher activity for electrolysis of CO₂ with a current density of 1.50A cm⁻²@2.0 V at 800 °C. It is clear from these results that the number of n in (La₄Sr_n−4)_0.9Ti_0.9nNi_0.1nO_3n+2 with Ni-doping is a key factor in controlling the electrochemical performance and catalytic activity in SOEC.