Black Phosphorus Nanosheet/Tin Oxide Quantum Dot Heterostructures for Highly Sensitive and Selective Trace Hydrogen Sulfide Sensing

Conductometric detection of hydrogen sulfide (H2S) gas is highly desired in the fields of environmental protection and noninvasive human health assessment due to its unique merits of real-time monitoring, low cost, and high miniaturization. In this regard, semiconducting metal oxides, such as tin oxide (SnO2), have been extensively employed for H2S detection but suffer from constrained sensitivity, elevated operation temperature, and poor selectivity. To overcome these drawbacks, mixed-dimensional heterostructures of two-dimensional (2D) black phosphorus (BP) nanosheet-templated zero-dimensional (0D) SnO2 quantum dots (QDs) (BP/SnO2) were prepared in this work for trace H2S detection. The constituent ratio-optimized BP/SnO2 sensors showed a high response of 233.8 and swift response/recovery speeds of 16.4/9.5 s toward 5 ppm H2S and ultralow energy consumption at a relatively low operation temperature (10 mW@130 °C), rivaling or surpassing that of most of the sensors in recent academic reports and commercial products. Moreover, excellent repeatability, long-term stability, and selectivity were demonstrated. When exposed to 5 ppm H2S under 80% relative humidity, the sensor displayed a 75% response retention with respect to the dry case, revealing a favorable humidity tolerance. Furthermore, the BP/SnO2 sensors outperformed their reduced graphene oxide (rGO)- and molybdenum disulfide (MoS2)-templated counterparts in terms of response intensity and response/recovery speeds. Benefiting from the abundant p–n heterojunctions and sufficient material utility within the mixed-dimensional heterostructures, the as-prepared BP/SnO2 sensors showcased brilliant application prospects for energy-saving and portable H2S detection systems.