Pt and black phosphorus co-modified flower-like WS₂ composites for fast NO₂ gas detection at low temperature

Incomplete recovery, baseline drift, and a long response time have been impeding the practical applications of transition metal dichalcogenide (TMD)-based gas sensors. Here, we report WS₂ sensors with significantly improved gas recovery, rapid response, and negligible baseline drift by the incorporation of black phosphorus (BP) as well as the decoration of Pt to detect NO₂ for the first time. Compared to bare WS₂, the BP-WS₂ sensors show higher sensitivity, better repeatability, and more excellent selectivity towards NO₂ at the optimal operating temperature of 50 °C. Furthermore, the optimized 30%BP-WS₂/Pt sensors exhibit a continuous enhancement in the recovery level and sensitivity with negligible baseline drift. The 30%BP-WS₂/Pt sensor also exhibits a shorter response time of 28 s than 49.5 s for its counterpart WS₂ sensor towards 32 ppm NO₂. The enhanced sensing properties are primarily due to the combined effects of more adsorption sites provided by BP, the spill-over effect of Pt catalysis, and the WS₂/BP heterostructure. Therefore, the Pt-decorated 30%BP-WS₂ sensor exhibits prominent gas-sensing properties of high gas sensitivity, a low detection limit of 100 ppb, good selectivity, and fast response. Our strategy provides a new route for designing and optimizing TMD-based gas sensors with excellent gas-sensing performance.