Tandem Electric-Fields Prolong Energetic Hot Electrons Lifetime for Ultra-Fast and Stable NO2 Detection.

Prolonging energetic hot electrons lifetimes and surface activity in the reactive site can overcome the slow kinetics and unfavorable thermodynamics of photo-activated gas sensors. However, bulk and surface recombination limit simultaneous optimization of both kinetics and thermodynamic. Here we deploy tandem electric-fields at (111)/(100)Au-CeO2 to ensure a sufficient driving force for carriers transfer and elucidate the mechanism of the relationship between charges transport and gas-sensing performance. The asymmetric structure of (111)/(100)CeO2 facet junction provide interior electric-fields, which facilitates electron transfer from (100)face to (111)face. This separation of reduction and oxidation reaction sites across different crystal faces helps inhibit surface recombination. The increased electron concentration at the (111)face intensifies the interface electric field, which promotes electron transfer to Au site. The local electric-field generated by the surface plasmon resonance effect promotes the generation of high energy hot-electrons, which maintains charge concentration in interface field by injecting into (111)/(100)CeO2, thereby provide thermodynamic contributions and inhibit bulk recombination. The tandem electric fields enable the (111)/(100)Au-CeO2 to rapidly detect 5 ppm of NO2 at room temperature with stability maintained within 20 s. This article is protected by copyright. All rights reserved.