Two-dimensional black phosphorus/tin oxide heterojunctions for high-performance chemiresistive H2S sensing

Hydrogen sulfide (H2S) emission from industrial fields and bacteria decomposing of sulfur-containing organic matter poses a significant impact on human health and atmospheric environment, thus necessitating the development of a H2S sensor with high sensitivity and exclusive selectivity especially at a very low dose. Chemiresistive sensors based on traditional metal oxides were readily limited by the elevated operating temperature and severe cross-sensitivity. To overcome these obstacles, we prepared two dimensional (2D) tin oxide (SnO2) nanosheets decorated with thin black phosphorus (BP) as the sensing layer of MEMS H2S sensors. Compared with pure SnO2 counterparts, BP-SnO2 sensors demonstrated lower optimal working temperature (130 degrees C vs. 160 degrees C), higher response (8.1 vs. 4.6) and faster response/recovery speeds (39.8 s/47.4 s vs. 79 s/140 s) toward 5 ppm H2S as well as larger sensitivity (1.3/ppm vs. 0.342/ppm). In addition, favorable repeatability, long-term stability, selectivity and humidity tolerance were exhibited. Thin BP not only served as an excellent conductivity platform within the composites, but enriched the adsorption sites by constructing p-n heterojunctions and introducing more oxygen vacancy, thus separately accelerating and strengthening the gas-solid interaction. This study showcased the application superiorities of BP nanosheets in the field of gas sensing, simultaneously providing a new strategy for trace H2S sensing via the 2D heterojunctions.

Automated summary

Hydrogen sulfide (H2S) emission and decomposition of sulfur-containing organic matter have a significant impact on human health and the environment. To address this issue, researchers developed a H2S sensor using two-dimensional tin oxide (SnO2) nanosheets decorated with thin black phosphorus (BP) as the sensing layer. The BP-SnO2 sensor demonstrated higher sensitivity, lower operating temperature, faster response/recovery speeds, and better stability compared to pure SnO2 sensors. This study highlights the potential of BP nanosheets in gas sensing and provides a new strategy for trace H2S sensing.