Cataluminescence on 2D WS2 Nanosheets Surface for H2S Sensing

Abstract In the present work, two-dimensional (2D) transition metal dichalcogenides (TMDs) WS2 nanosheets, which was synthesized through simple ultrasonic-assisted liquid exfoliation, was used for constructing H2S CTL gas sensor for the first time. With respect to other H2S CTL gas sensors based on metal oxides and metal-free materials, this sensor based on WS2 nanosheets is outstanding in H2S sensing with excellent properties at relative low temperature of 187 ℃. Furthermore, both of the response and recovery time are as fast as 0.2 s with linear range of 0.26-6.38 µg·mL-1 (R2=0.9933) and detection limit of 0.06 µg·mL-1 (S/N=3). The characterization results showed that as-prepared WS2 nanosheets had larger surface, richer edges and more sulfur defects by comparing with bulk WS2, which are beneficial for catalytic performance improving. Importantly, the possible mechanism is proposed. In detail, some amount of WO3 were in-situ generated forming WS2/WO3 hybrids, and WO3 could keep exchange balance with WS2 during H2S sensing attributed to repeatable S-O bonding exchange. This is crucial for the repeatability of the sensor. This work provides a new view for CTL gas sensing mechanism and may open a new avenue of applying TMDs in H2S CTL sensors.