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

Abstract

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_0.9Cs_0.1Co₂O_4-δ (MCCO) and Co₃O₄ (CO) (MCCO–CO, 8:2 mass ratio). At 600 °C, the MCCO–CO electrode exhibits a low area-specific resistance of 0.382 Ω cm² 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 H₂ production rates of 4.65 mL min⁻¹ cm⁻² at 1.5 V and 700 °C, respectively, with reasonable Faradaic efficiencies.