Templated bicontinuous Tin oxide thin film fabrication and the NO2 gas sensing

• Bicontinuous SnO2 thin film is fabricated by templating nanoporous gold leaf via ALD.
• The annealed SnO2 film shows the working-temperature dependence on NO2 sensing.
• The NO2 detection limit is 170 ppb with a rapid response/recovery time of 40/130 s.
• We test the NO2 sensing performance at the gas flow of dry N2 or air.
• The in-depth mechanism of SnO2 film on NO2 sensing is elucidated.

Bicontinuous Tin oxide (SnO2) thin films were fabricated by atomic layer deposition (ALD), annealing, and acid washing with nanoporous gold (NPG) structure serving as templates. The resultant SnO2 films show high sensitivity on NO2 gas. The detection limit is as low as 170 ppb in dry N2 flow with a rapid response/recovery time of 40/130 s at the optimized working temperature of 300 °C. The performances dependence of the gas sensor on the working temperatures and the exposure environments reveal that the gas responses strongly rely on the dynamic balance of O2, O2−O2−, O−, NO2−NO2−, and NO3−NO3−. Our study not only shows this bicontinuous SnO2 films is promising for sensitive gas sensor but also provides insightful understanding on the NO2 gas sensing mechanism.

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