Rutile-Type CoTiNbO-Based Cathode with In Situ Exsolved Metal Particles for Direct CO Electrolysis.

Rutile-type CoTiNbO (CTO)-based materials doped with Fe or Ni were investigated as cathode electrodes to modify their electrical conductivity and electrocatalysis toward CO splitting. Higher electric conductivity was found in CoFeTiNbO (CTO-Fe, 0.78 S cm) and CoNiTiNbO (CTO-Ni, 2.10 S cm) compared to CTO (0.49 S cm) after the reduction at 800 °C in Ar-5% H. Co and Co-Ni particles exsolved in situ from the surface of CTO, CTO-Fe, and CTO-Ni after reduction. CTO-Ni and CTO-Fe cathodes did better in the CO electrolysis at 800 °C than the CTO one, but the CTO-Ni cell was unstable after 10 h of operation due to the carbon deposition that blocked the electrode. The cell with CTO-Fe demonstrated a good stability for CO splitting in 100 h. This work demonstrates that rutile-type CTO-based cathodes are promising to provide an efficient and candidate oxide cathode for the electrolysis of CO.