Effects of the Atmosphere in a Hydrothermal Process on the Morphology and Photocatalytic Activity of Cerium Oxide

Abstract The hydrothermal method is widely applied in nanomaterials synthesis, and most of the influencing factors have already been taken into account. However, the effect of atmosphere in solution on the performance of nanomaterials has been underestimated for a long time. In this article, reaction solvents were saturated with three classical gases (argon, oxygen, and carbon dioxide), and then heated at 180 °C for 24 h to obtain the cerium dioxide (CeO 2 ) nanoparticles. The properties of the three types of CeO 2 are significantly different from that of the normal CeO 2 (without gas saturation). The morphologies of the prepared CeO 2 particles are different, even appear the hollow structure in CeO 2 −CO 2 (synthesized in CO 2 saturated condition). The more absorbing and meaningful thing is that the photocatalytic activity of CeO 2 −CO 2 has been greatly improved. The concordance of the CO 2 atmosphere (acid gas) and CeO 2 (owning substantial content of basic sites) is the key point for the excellent photocatalytic performance.