Growth of small sized CeO2 particles in the interlayers of expanded graphite for high-performance room temperature NOx gas sensors

In this paper, CeO2/graphene-like nanosheet composites (CeGNCs) have been synthesized via a facile solvothermal reaction. In the synthesis, the Ce(NO3)3 precursor was fully infused into the interlayers of expanded graphite (EG) under vacuum-assisted conditions, and then CeO2 nanoparticles grow in situ in the interlayers of inexpensive EG under solvothermal conditions to form CeGNCs. The results show that the CeO2 particles with an average diameter of about 3 nm are highly dispersed on the graphene-like nanosheet (>10 layers). The synergy between the tiny size of CeO2 and good conductivity of the graphene-like nanosheet is favorable for improving the gas sensing property of composites. The gas sensing tests indicate that the CeGNCs have superior performances to the pure CeO2. Especially, the CeGNCs with 46.7 wt% of CeO2 show higher NOx gas sensing performance with low detection limit of 5.0 ppm, high sensitivity of 10.39% and short response time of 7.33 s compared to 100 ppm NOx at room temperature, which is more than 4.6 times higher compared with the pure CeO2. Hence, the approach developed in this work would be important for the low-cost and large-scale production of the CeGNC material with highly promising applications in gas sensors.