An efficient vapor-phase processing method derived mesoporous N-C@SnO2-Co3O4 hollow nanoboxes with abundant surface oxygen vacancy for highly improved gas sensing application

Highlights: • Mesoporous N-C@SnO₂-Co₃O₄ hollow nanoboxes were obtained via vapor-phase processing. • N-C dopant helped greatly improve gas sensing properties than SnO₂-Co₃O₄ counterpart. • High acetone selectivity accompanied with anti-humidity and low working temperature. • Oxygen vacancy derived from N-C dopant contributed to the enhanced sensing mechanism. -- Abstract: For widely used semiconductor-based chemoresistive sensors, low sensitivity and poor anti-interference in the complex environment (humidity resistance, etc.) are two main constraints of application. To enhance the sensitivity, many effective strategies have been developed such as constructing heterostructures with synergistic effects, introducing abundant oxygen vacancies as active sites, designing hollow/cavity structure to increase surface area to facilitate target gas adsorption, and so on. Besides, the interference caused by water vapor can be blocked.via MOF or molecular sieve membranes but is accompanied with the shielding of some target molecules. The above methods are faced with the problems of complex process, large workload of material screening and failure to maintain the device stability. Hence, an effective vapor-phase method derived N-C@SnO₂-Co₃O₄ complex that combined the hydrophobicity, acetone selectivity, p-n heterostructure with mesoporous hollow characteristics was proposed, named mesoporous N-C@SnO₂-Co₃O₄ hollow nanoboxes (HNBs). Particularly, the chemoresistive sensor based on N-C@SnO₂-Co₃O₄ HNBs (2.0%) showed satisfactory selectivity to acetone vapor at relatively low working temperature (160 °C), and the response remained stable even under high humidity (with the R.H. of 90%). Impressively, a three-fold enhancement in response signal was observed for the sensor based on N-C@SnO₂-Co₃O₄ HNBs when compared with its counterpart of SnO₂-Co₃O₄, which can be ascribed to the consequent unpaired electrons from oxygen vacancies and hollow mesoporous structures. Additionally, a sensing prototype based on the N-C@SnO₂-Co₃O₄ HNBs was practically fabricated. The satisfactory sensing response and stability further verified the potential applications in industrial acetone detection. This facile vapor-phase approach sheds light on designing sensing materials with enhanced sensitivity and humidity resistance, as well as device stability simultaneously.