A-site deficient perovskite with nano-socketed Ni-Fe alloy particles as highly active and durable catalyst for high-temperature CO2 electrolysis

Abstract

The solid oxide electrolysis cell (SOEC) has attracted increased attention in recent years due to its capability to reduce CO2 emissions in a highly efficient and environmentally sustainable fashion. Previous work in our group has fabricated an A-site Ce doped La0.7Sr0.3Cr0.5Fe0.5O3-δ (LSCrF) with gadolinium doped ceria (GDC) as the cathode material in SOEC by the conventional method. This composite cathode presents a satisfying electrochemical performance and good stability due to the presence of excessive oxygen vacancies and strong CO2 adsorption ability. However, its electrochemical catalytic activity is still limited by the catalyst specific area. Hence, the optimization of electrode microstructure is considered as a promising way to further improve the SOEC performance by increasing the active reaction area. In this study, highly active (La0.65Sr0.3Ce0.05)0.9(Cr0.5Fe0.5)0.85Ni0.15O3-δ (Ni-LSCeCrF)/GDC nanostructured cathode was successfully fabricated by incorporating infiltration and in situ exsolution processes. The optimized microstructure contains fine and uniformly distributed perovskite particles on GDC backbone with nano-socketed Ni-Fe alloy nanoparticles. The Ni-LSCeCrF/GDC cathode shows significantly improved electrochemical performance, CO production rate, and Faraday efficiency for CO2 reduction reaction. Furthermore, the density functional theory calculations show that Ni doping could reduce the segregation energy of Fe, revealing a new strategy of multiple elements doping to form active alloy by in situ exsolution.