Novel silicon carbide nanosheets were synthesized by a carbothermal reduction reaction. We studied their high-temperature gas sensing properties and the mechanism of n–p conductivity transition during gas sensing tests.

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.

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Two‐dimensional (2D) structure is a good candidate for fabricating humidity sensors due to its advantages including high surface/volume ratio, abundant active sites, and fast carrier motion rate. Here, an impedance‐type nonoxide humidity sensor based on silicon carbide nanosheets (SiC NSs) is prepared via carbothermal reduction between graphene oxide and silicon powder. The final product, with a high surface area of 90.1 m2 g−1, contains SiC with a thin oxide layer on the surface and some remained reduced graphene oxide. The synthesized SiC NSs exhibit excellent sensing properties such as a high sensitivity to water in ambient atmosphere (16991.1 at 95% relative humidity (RH)), a wide range of RH response (11–95%), short response time (3 s) and recovery time (3 s), and good linear response toward humidity, which are more excellent than the commercial SiC nanowires and most of the nanostructure humidity sensors in literature. The good humidity sensing performance of this sample can be contributed to the advantage of nanosheet structure, the fast electron transfer rate in the SiC semiconductor, and the donor effect of electrons. This report provides a technical guidance on the designing of novel 2D structure nonoxide humidity sensors.