Harnessing the electrocatalytic potential of in-situ exsolution of Ni nanoparticles on lanthanum and calcium co-doped strontium titanate for CO2 reduction in solid oxide electrolysis cells

Abstract

The exsolution phenomenon of metal nanoparticles from a perovskite oxide involves the creation of oxygen vacancies, contributing to improved catalytic activity for CO2 reduction. In this context, a B-site Ni-doped and A-site La, Ca co-doped strontium titanate, denoted as La0.20Sr0.25Ca0.45Ni0.05Ti0.95O3-δ (Ni-LSCT), is synthesized with the aim of serving as a highly efficient cathode in conjunction with LSM as the anode and YSZ as the electrolyte for CO2 reduction via solid oxide electrolysis process. The incorporation of 5 mol% Ni doping at the B-site of the perovskite is successfully achieved, leading to the subsequent release of highly dispersed nanoparticles upon exposure to a reducing environment. YSZ-electrolyte-supported SOECs featuring the Ni-LSCT cathode demonstrate a notable current density of 0.93 A/cm2 at an applied voltage of 2.5 V at 800 °C in pure CO2. Moreover, at the same temperature, the reduction current density measures 1.21 A/cm2 when the Ni-LSCT serves as the cathode in a 70/30 molar ratio (CO2/H2) environment and 1.73 A/cm2 with a 50/50 molar ratio of the feed gas, both at an applied voltage of 2.5 V. This suggests an enhanced CO2 reduction performance in a reducing atmosphere. The introduction of Ni doping into LSCT enhances the electrochemical activity of the cathode by augmenting oxygen vacancies, while the presence of Ni nanoparticles on the cathode surface intensifies the active sites. Collectively, this innovative electrocatalyst configuration presents promising prospects for CO2 electrolysis within the SOEC framework.