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

Compositesof graphene and CeO2 nanoparticleswith high-energy{100} facets exposed are prepared by the hydrothermal method. Thepercentage of high-energy {100} polar plane increases with elevatingtemperature, 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 temperatureis enhanced. First-principles calculations are done to uncover themechanism. The adsorption energy of NO2 on the six-coordinatedCe of the CeO2{100} polar plane is the most negative, indicatingthe most preferred sites for the adsorption of NO2. However,if more O-v are generated, the proportion of six-coordinatedCe atoms will be reduced, and the interaction with NO2 willbe reduced because of charge recombination. Consequently, the sensingperformances toward NO2 are deteriorated. The results providenew information pertaining to the design and fabrication of room-temperaturesensing materials for NO2.