Cu infiltrated Ni-YSZ cathode in CO2 (+H2) stream: Reverse water gas shift vs. CO2 electrolysis

Abstract

Ni-Yttria Stabilized Zirconia (Ni-YSZ) cermet electrode is known to perform in CO₂ (+H₂) stream. Introducing H₂ in CO₂ containing streams enables thermochemical reverse water gas shift reaction (rWGS: CO₂ + H₂ → CO + H₂O) at open circuit. Without the application of any bias, the rWGS responds positively to an increase in temperature and concentrations of CO₂ and H₂. Application of bias results in enhancement in CO yield above the rWGS baseline value. With bias, both CO₂ and H₂O electrolysis are enabled. The infiltration of Cu on the Ni-YSZ backbone results in significant improvement of the reaction kinetics and increases H₂ and CO production. Impedance analysis indicates that the kinetic limitation originates from reaction steps with slower time constants with Ni{Cu}_x-YSZ outperforming Ni-YSZ in this aspect. Cu infiltration suppresses particle coarsening typically observed in Ni-YSZ.