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

Abstract

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 NO_x 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 NO_x 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.