High-performance Ruddlesden–Popper perovskite oxide with in situ exsolved nanoparticles for direct CO2 electrolysis

Abstract

Carbon dioxide (CO₂) is one of the principal greenhouse gases accountable for global warming and extreme climate changes. Electrochemically converting CO₂ into carbon monoxide (CO) is a promising approach for CO₂ utilization in achieving industrial decarbonization. High-temperature CO₂ electrolysis via solid oxide electrolysis cells (SOECs) has great potential, including high-energy efficiency, fast electrode kinetics, and competitive cost; however, this technology still has challenges associated with developing highly active, robust CO₂ electrodes for SOECs. We report novel Ruddlesden–Popper structured Pr_1.2Sr_0.8Mn_0.4Fe_0.6O_4−δ (RP-PSMF) with in situ exsolved Fe nanoparticles as the CO₂ electrode in SOECs for direct CO₂ conversion to CO. The mechanism of CO₂ electrolysis is studied by using the distribution of relaxation times method from electrochemical impedance spectroscopy. La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ (LSGM)-electrolyte supported SOECs with the RP-PSMF cathode have achieved exceptionally high current densities of 2.90, 1.61, 0.91, and 0.48 A·cm⁻² at an applied voltage of 1.5 V at 800, 750, 700, and 650 °C, respectively. Moreover, SOECs with the RP-PSMF cathode have exhibited a stable electrolysis performance for 100 h under a current cycling operation. These results suggest that RP-PSMF with exsolved Fe nanoparticles is a highly promising cathode for high-temperature direct CO₂ electrolysis cells.