Investigation of CO2 Splitting on Ceria-Based Redox Materials for Low-Temperature Solar Thermochemical Cycling with Oxygen Isotope Exchange Experiments

The surface exchange and bulk transport of oxygen are highly relevant to ceria-based redox materials, which envisaged for the solar thermochemical splitting carbon dioxide in future. Experimental investigations isotope on CeO2-δ, Ce0.9M3+0.1O1.95-δ (with M3+ = Y, Sm) Ce0.9M4+0.1O2-δ M4+ Zr) samples were carried out first time utilizing oxygen-isotope-enriched C18O2 gas atmospheres as tracer source, followed by Secondary Ion Mass Spectrometry (SIMS), at temperature range 300 ≤ T 800 °C. experimental K˜O D˜O data reveal promising results terms CO2 when trivalent (especially Sm)-doped ceria is employed. reaction temperatures lower than previously proposed/reported due weak dependency parameters D˜O. majority experiments show higher values Sm-doped cerium comparison Y-doped Zr-doped ceria, well nominally undoped ceria. apparent activation energies both lowest Using oxide exhibits various negative aspects. Zr-doping enhances reducibility, but possible Zr-based alteration effects dopant-induced migration barrier enhancement detrimental diffusion