Water pretreatment promoting the removal of indoor formaldehyde over nano-CeO2 at ambient temperature

Abstract

An efficient and noble-metal-free catalyst is of practicality for the ambient temperature removal of indoor formaldehyde (HCHO), which severely threats human health. In this study, a commonly used nano-CeO₂ material is improved via a simple water pretreatment for efficient HCHO removal at ambient temperature. Notably, CeO₂ pretreated with 20 mL of deionized water at 80 °C (CeO₂-20–80) shows a HCHO removal efficiency of 77.3% and HCHO conversion efficiency of 44.9% in 3 h, which is much higher than CeO₂ (p-CeO₂) without water pretreatment. Indoor fluorescent light further boosts the conversion of HCHO into CO₂ with a HCHO removal efficiency of 80.0% and HCHO conversion efficiency of 67.7%. Various characterizations, including XRD, Raman spectroscopy, N₂ sorption isotherm, XPS, EPR and theoretical calculations, reveal that the preferential adsorption of H₂O molecule on the (220) crystal facet of CeO₂, high specific surface area, a large amount of reactive oxygen species and easier adsorption of the HCHO on the (111) crystal facet than (220) of CeO₂ are responsible for the enhanced HCHO removal performance of CeO₂-20–80. This study provides insight into the improvement of cost-effective catalysts using a simple way and the full utilization of energies on hand for pollution control.