Abstract
Paired charge-compensating doped ceria has great potential for solar thermochemical splitting of H2O and CO2 because of its balanced reduction and oxidation properties.
Highlights
The thermochemical splitting of H2O and CO2 via two-step redox cycles driven by concentrated solar energy is a favorable thermodynamic pathway to produce renewable fuels, because it uses the entire solar spectrum to generate H2/CO and O2 in separate steps.[1,2,3] Nonstoichiometric ceria has emerged as the benchmark redox material mainly due to its fast kinetics and morphological stability[4,5,6,7,8] even a er hundreds of consecutive redox cycles.[9]
The fabrication of the Paired charge-compensating doped ceria (PCCD) materials was successful as dopant concentrations were within 1 mol% of the nominal values, as determined by ICP-OES
We found that the PCCD materials are phase pure and stable over multiple redox cycles
Summary
The thermochemical splitting of H2O and CO2 via two-step redox cycles driven by concentrated solar energy is a favorable thermodynamic pathway to produce renewable fuels, because it uses the entire solar spectrum to generate H2/CO and O2 in separate steps.[1,2,3] Nonstoichiometric ceria has emerged as the benchmark redox material mainly due to its fast kinetics and morphological stability[4,5,6,7,8] even a er hundreds of consecutive redox cycles.[9]. The technical feasibility of this cycle has been experimentally demonstrated with a 5 kW solar reactor, yielding high selectivity, stability, mass conversion and solar-to-fuel energy efficiency.[10] due to its relatively low reducibility, pure ceria requires T > 1773 K and pO2 < 10 mbar to achieve even moderate values of Dd. Doping ceria with tetravalent transition metals such as Zr4+ 14 and 17) increases Dd under the same T and pO2, while other dopants fail to do so.[1,11,14,17,18,19,20,21,22,23,24,25] Hercynite and selected perovskites, e.g. Sr- and Mn-doped LaAlO3, have lower reduction enthalpies and achieve higher reduction extents,[26,27,28] but they suffer from less favorable oxidation thermodynamics, which leads to lower speci c fuel yields under most conditions.[29] the search continues for metal oxides which balance the energetics of reduction and oxidation to yield high solar-to-fuel energy conversion efficiencies
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