Heterogeneity in the Mo doped La0.55Sr0.45FeO3 cathode for direct CO2 electrolysis

The large-scale integration of intermittent renewable energies into the power grid could reduce the CO2 emission from the combustion of fossil fuel, but it requires energy storage techniques to balance the energy production and demand. The electrolysis of CO2 that converting electricity into chemicals/fuels provides a sustainable way of energy storage and CO2 reduction. Solid oxide electrolysis cell (SOEC) operating at around 800 degrees C was able to provide highly efficient transformation of CO2 because the high temperature was able to decrease the energy demand and increase the activation of CO2 than room temperature electrolysis. In this study, Mo-doped ferrite perovskite, La0.55Sr0.45Fe0.85Mo0.15O3, was studied as the cathode of an SOEC for the direct electrolysis of CO2 at 800 degrees C. Cell with La0.55Sr0.45Fe0.85Mo0.15O3 cathode showed a significantly higher current density during CO2 electrolysis than the one with La0.55Sr0.45FeO3 cathode. Compared with the parent La0.55Sr0.45FeO3 cathode that will subject to a superficial decomposition into Fe-0 and SrO or SrCO3 at an elongated cathodic bias of -1.4 V, Mo-doping will induce the production of Ruddlesden-Popper phase (e.g. (La,Sr)(2)(Mo,Fe)O-4, Fe-Mo-O oxides and Fe-0). La0.55Sr0.45Fe0.85Mo0.15O3 cathode was found to an unobvious current decrease at -1.1 V, but a cell degradation was found under a high bias of -1.4 V. During the 97 h' aging under a cathodic bias (-1.4 V), the reduced molybdenum cation in La0.55Sr0.45Fe0.85Mo0.15O3 was found to be less mobile than Fe3+/2+, La3+ or Sr2+, and the perovskite with Fe-deficit region were also found to be important for the activation of CO2 and dissociation of CO in the electrochemical process.

Automated summary

The large-scale integration of intermittent renewable energies into the power grid can reduce CO2 emissions from fossil fuel combustion, but energy storage techniques are required to balance energy production and demand. The electrolysis of CO2, converting electricity into chemicals/fuels, offers a sustainable energy storage and CO2 reduction method. This study investigates the use of a Mo-doped ferrite perovskite as a cathode material in a solid oxide electrolysis cell (SOEC) for the direct electrolysis of CO2 at high temperatures. The Mo-doped cathode shows higher current density during CO2 electrolysis compared to the undoped cathode, and the presence of Mo-doping leads to the production of Ruddlesden-Popper phase and Fe-Mo-O oxides. However, the Mo-doped cathode exhibits degradation under high bias, suggesting the need for further optimization.