Synthesis of ultra-small Ag nanoparticles decorated on hierarchical porous α-Fe2O3 hollow microspheres for highly efficient H2S gas sensors

초록

In this report, the ultra-small Ag nanoparticle-decorated hollow alpha-Fe2O3 microspheres were successfully synthesized by facile hydrothermal method using uniform carbon microspheres as a hard template. The ultra-small Ag nanoparticle-doped hollow alpha-Fe2O3 spherical microstructures were assembled by primary alpha-Fe2O3 nanorods. The gas sensing properties of the Ag nanoparticles-decorated hollow alpha-Fe2O3 microspheres have been investigated for H2S gas detection. It was found that the sensors based on Ag-doped alpha-Fe2O3 showed good gas sensing performance for H2S with high response, fast response time, ultra-low detection limit and good selectivity. At the optimal working temperature, the response of the Ag3-alpha-Fe2O3 nanocomposite sensor was 33 for 10 ppm H2S, which was 8 times higher than that of the pure hollow alpha-Fe2O3 microsphere sensors. Furthermore, the response time of this sensor (3 s) was shorter than that of the pristine alpha-Fe2O3 sensor (97 s). The remarkable improvement in H2S gas sensing properties of the Ag nanoparticles-doped hollow alpha-Fe2O3 microspheres may be due to the formation of ohmic contact between the noble metal Ag and alpha-Fe2O3, as well as the unique catalytic behavior of silver nanoparticle in the dissociation of H2S molecules. These effects increase number of adsorption/reaction sites for oxygen and target gas, leading to improved charge transfer and enhanced reaction kinetics.

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