High-Temperature Gas Sensor Based on Novel Pt Single Atoms@SnO2 Nanorods@SiC Nanosheets Multi-heterojunctions.

Designing a novel heterojunction structure on a SiC gas sensing material is extremely desirable for high-performance gas sensors applied in harsh environments. Inspired by the unprecedented catalyzing effect of single-atom catalysts, here, we have sequentially loaded tin oxide nanorods (SnO2 NRs) and platinum single atoms (Pt SAs) on silicon carbide nanosheets (SiC NSs) to build a novel Pt SAs@SnO2 NRs@SiC NSs multi-heterojunction. Gas sensors based on Pt SAs@SnO2 NRs@SiC NSs show highly enhanced gas sensing performance, including high response (119.75 ± 3.90), ppb level detecting, short response/recovery time (∼14 and ∼ 20 s), good selectivity, and excellent stability under high temperature. Particularly, the Pt SAs@SnO2 NRs@SiC NSs gas sensor has a response larger than 30 even under 500 °C and possesses good long-term stability. Such improvement of sensing performance can be attributed to the catalyzing effect of Pt single atoms, band gap tuning of the SnO2 nanostructure, promoted electron transfer of SnO2@SiC, and high surface area of two-dimensional (2D) SiC nanosheets. This approach enlightens the perspective application of single-atom catalysts, small-size effect of SnO2 nanorods, and 2D nanostructure on gas sensing fields and provides new routes for designing new types of gas sensing materials.