An Efficient Trifunctional Spinel-Based Electrode for Oxygen Reduction/Evolution Reactions and Nonoxidative Ethane Dehydrogenation on Protonic Ceramic Electrochemical Cells.

Protonic ceramic electrochemical cells (PCECs) have received considerable attention as they can directly generate electricity and/or produce chemicals. Development of the electrodes with the trifunctionalities of oxygen reduction/evolution and nonoxidative ethane dehydrogenation is yet challenging. Here these findings are reported in the design of trifunctional electrodes for PCECs with a detailed composition of Mn 0.9 Cs 0.1 Co 2 O 4-δ (MCCO) and Co 3 O 4 (CO) (MCCO-CO, 8:2 mass ratio). At 600 °C, the MCCO-CO electrode exhibits a low area-specific resistance of 0.382 Ω cm 2 and reasonable stability for ≈105 h with no obvious degradation. The single cell with the MCCO-CO electrode shows an encouraging peak power density of 1.73 W cm -2 in the fuel cell (FC) mode and a current density of -3.93 A cm -2 at 1.3 V in the electrolysis cell (EC) mode at 700 °C. Moreover, the MCCO-CO cell displays promising operational stability in FC mode (223 h), EC mode (209 h), and reversible cycling stability (52 cycles, 208 h) at 650 °C. The MCCO-CO single cell shows an encouraging ethane conversion to ethylene (with a conversion of 40.3% and selectivity of 94%) and excellent H 2 production rates of 4.65 mL min -1 cm -2 at 1.5 V and 700 °C, respectively, with reasonable Faradaic efficiencies.