A chromium oxide coated nickel/yttria stabilized zirconia electrode with a heterojunction interface for use in electrochemical methane reforming

Abstract

This work investigated the use of nickel/yttria stabilized zirconia (Ni/YSZ) coated in situ with chromium oxide (Cr₂O₃) for electrochemical methane (CH₄) reforming in solid oxide electrolysers. Combined analysis using X-ray diffraction spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy confirmed the formation of Cr₂O₃ on the Ni surface with a heterojunction interface formed by reducing nickel chromite (NiCr₂O₄) to a core–shell structure. The electrical properties of the Cr₂O₃ coated Ni/YSZ were investigated and correlated to the electrochemical performance. Significant improvements of electrode activity were achieved with Cr₂O₃ coated Ni/YSZ in contrast to traditional Ni/YSZ in a CH₄ atmosphere. Strong carbon deposition resistance was also observed in a methane–carbon dioxide (CH₄–CO₂; 1 : 1) atmosphere at 800 °C. Significant enhancement in electrochemical CH₄–CO₂ reforming was successfully achieved in oxide ion conducting electrolysers with Cr₂O₃ coated Ni/YSZ cathodes.