Enhancing Electrochemical Efficiency of Solid Oxide Electrolysis Cells for Carbon Dioxide Reduction Through Nickel-Doped Titanate-Based Cathode with Doped Ceria Electrolyte

Abstract

Solid oxide electrolysis cell (SOEC) is a potential technology for converting the principal greenhouse gas, carbon dioxide (CO₂), into carbon monoxide (CO) by employing renewable energy. SOECs have great potential, including high-energy efficiency, fast electrode kinetics, and competitive cost; however, this technology still has challenges in developing highly active, robust CO₂ cathode electrocatalysts. In this work, we report the Ni-doped lanthanum strontium calcium titanate (La_0.20Sr_0.25Ca_0.45Ni_0.05Ti_0.95O_3−δ) cathode for application as the cathode of CO₂ electrolysis with gadolinia-doped ceria (Gd_0.1Ce_0.9O_1.95) electrolyte in SOEC. The exsolution of Ni nanoparticles is achieved by a simple in situ growth method at 800 °C. The Ni doping in LSCT significantly improved the electrochemical activity of the catalyst by increasing oxygen vacancies, and the Ni metallic nanoparticles can afford much more active sites for CO₂ reduction. The CO₂ electrolysis mechanism is studied by the distribution of relaxation time analysis of impedance spectroscopy. Ni-LSCT renders a higher activity for electrolysis of CO₂ with an exceptionally high reduction current density of 3.89 A cm⁻² at 2.5 V potential applied and 800 °C temperature with GDC (Gd_0.1Ce_0.9O_1.95) electrolyte. Ni doping is a crucial factor in controlling the electrochemical performance and catalytic activity in SOEC and GDC electrolytes, which is further helped by the high ionic conductivity.