Polar Cubic CeO₂ Nanoparticles on Graphene for Enhanced Room-Temperature NO₂ Sensing Performance

Composites of graphene and CeO₂ nanoparticles with high-energy {100} facets exposed are prepared by the hydrothermal method. The percentage of high-energy {100} polar plane increases with elevating temperature, but the proportion of Ce³⁺ and oxygen vacancy (O_v) decreases. As a result, the sensitivity of CeO₂{100}/graphene composites toward NO₂ at room temperature is enhanced. First-principles calculations are done to uncover the mechanism. The adsorption energy of NO₂ on the six-coordinated Ce of the CeO₂{100} polar plane is the most negative, indicating the most preferred sites for the adsorption of NO₂. However, if more O_v are generated, the proportion of six-coordinated Ce atoms will be reduced, and the interaction with NO₂ will be reduced because of charge recombination. Consequently, the sensing performances toward NO₂ are deteriorated. The results provide new information pertaining to the design and fabrication of room-temperature sensing materials for NO₂. © 2023 American Chemical Society.