Utilization of both-side metal decoration in close-packed SnO₂ nanodome arrays for ultrasensitive gas sensing

Metal decoration on hollow metal oxide nanostructures is an attractive route to enhance gas sensing properties. Herein, we present a facile method for the utilization of metal decoration on both the inner and outer surfaces of hollow metal oxide nanostructure for the first time. Close-packed SnO₂ nanodome arrays decorated with Au nanoparticles are fabricated by soft-template method and self-agglomeration of an Au film. The position of Au decoration for SnO₂ nanodome arrays is controlled by changing the deposition sequence of Au and SnO₂ films. While inside, outside, and both-side Au-decorated SnO₂ nanodome arrays show much higher responses to various gases than a bare SnO₂ nanodome, it is shown that the response of both-side Au-decorated SnO₂ nanodome arrays to C₂H₅OH at 300 °C is 18 times higher than that of the bare SnO₂ nanodome arrays and the theoretical detection limit is below 1 ppb. These are attributed to the catalytic effect of Au nanoparticles on the modulation of barrier potentials in links between the individual SnO₂ nanodomes. Our results demonstrate that the utilization of both-side metal decoration is an effective strategy for enhancing the gas sensing performance of hollow metal oxide nanostructures.