Multi-shelled CeO2 hollow microspheres as superior photocatalysts for water oxidation

A general self-templating method is introduced to construct triple-shelled CeO2 hollow microspheres, which are composed of tiny CeO2 nanoparticles. When the triple-shelled CeO2 hollow microspheres are used as photocatalysts for direct water oxidation with AgNO3 as the electron scavenger, excellent activity and enhanced stability for O-2 evolution are achieved, in contrast with commercial CeO2 nanoparticles, single-shelled CeO2 hollow microspheres and double-shelled CeO2 hollowmicrospheres. Such an outstanding performance is attributed to the unique properties of the triple-shelled CeO2 hollow microspheres including more efficient multiple reflections of the incident light by the inner shells, the larger surface area and more active sites for improving separation of electron-hole pairs, and the more curved surfaces unfavorable for deposition of in situ generated Ag nanoparticles.