Highly selective low-temperature triethylamine sensor based on Ag/Cr_2O_3 mesoporous microspheres

摘要

Cr_2O_3 mesoporous microspheres were synthesized via an ethanol solvothermal process and microspheres were prepared by a surfactant-modified method. The two products were characterized by XRD, EDX, XPS, TEM and HRTEM techniques. The diameter of Cr_2O_3 microspheres was 1-1.5 μm, which were further constructed by the building blocks of nanoplates. The Ag/Cr_2O_3 microspheres kept the morphology and mesoporous structure of Cr_2O_3 microspheres and Ag nanoparticles were successfully deposited on the surface of Cr_2O_3 microspheres with the particle size of 7-25 nm. The gas sensing properties of the Cr_2O_3 and Ag/Cr_2O_3 microspheres to triethylamine (TEA) were measured at different working temperatures. The response of Cr_2O_3 microspheres to 50 ppm TEA was 15.2 at working temperature of 170 ℃, while that of Ag/Cr_2O_3 increased to 52.9 at a lower temperature of 92 ℃. The modification of Ag nanoparticles not only greatly lowered the optimum working temperature, enhanced the response of Cr_2O_3 microspheres to TEA gas, but also further improved the selectivity of the sensor to TEA. The significant improvement of Ag/Cr_2O_3 microspheres to TEA gas sensing property could be attributed to the modified Ag sensitization and catalytic effect, and mesoporous structure of Cr_2O_3 microspheres.