Giant Onsite Electronic Entropy Enhances the Performance of Ceria for Water Splitting

Previous studies have shown that a large solid-state entropy of reduction increases thethermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical watersplitting cycles. In this context, the configurational entropy arising from oxygen offstoichiometryin the oxide, has been the focus of most previous work. Here we report a differentsource of entropy, the onsite electronic configurational entropy, arising from coupling betweenorbital and spin angular momenta in lanthanide f orbitals. We find that onsite electronicconfigurational entropy is sizable in all lanthanides, and reaches a maximum value of≈4.7 kB per oxygen vacancy for Ce4+/Ce3+ reduction [1]. This unique and large positive entropysource in ceria explains its excellent performance for high-temperature catalytic redox reactionssuch as water splitting. Our calculations also show that terbium dioxide has a high electronicentropy and thus could also be a potential candidate for solar thermochemical reactions.

کلیدواژه ها:

Water Splitting ، Ceria