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

Conductometric detection of hydrogen sulfide (H 2 S) 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 (SnO 2 ), have been extensively employed for H 2 S 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) SnO 2 quantum dots (QDs) (BP/SnO 2 ) were prepared in this work for trace H 2 S detection. The constituent ratio-optimized BP/SnO 2 sensors showed a high response of 233.8 and swift response/recovery speeds of 16.4/9.5 s toward 5 ppm H 2 S 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 H 2 S 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/SnO 2 sensors outperformed their reduced graphene oxide (rGO)- and molybdenum disulfide (MoS 2 )-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/SnO 2 sensors showcased brilliant application prospects for energy-saving and portable H 2 S detection systems.