Single-phase nickel-doped ceria cathode with in situ grown nickel nanocatalyst for direct high-temperature carbon dioxide electrolysis

Abstract

This paper reports the in situ growth of Ni nanocatalysts to anchor onto the CeO₂ surface to combine the surface oxygen vacancies and form heterogeneous catalysis sites with the aim of improving electrocatalytic activity through direct exsolution of Ni nanoparticles from the Ni-doped CeO₂ lattice in a reducing atmosphere at higher temperatures. The combined use of XRD, TEM, SEM and XPS confirms the in situ exsolution of Ni nanoparticles on the CeO₂ surface. The doping of CeO₂ with nickel leads to a charge redistribution and an increase of oxygen vacancy concentration. The electrical properties of Ce_1−xNi_xO₂ (x = 0, 0.05, 0.10, 0.15 and 0.20) are systematically investigated and correlated to their electrochemical performance in symmetrical and electrolysis cells. The electrical properties and electrochemical performances improve with increasing Ni contents. The Ce_0.85Ni_0.15O₂ cathode with anchored Ni nanocrystal shows the best electrochemical performances for carbon dioxide electrolysis with reasonable short-term stability; however, the electro-catalytic activity of Ce_0.8Ni_0.2O₂ with excess Ni particles on the surface rapidly decays because of adverse agglomeration of Ni particles at high temperatures.