Design of a ppb-level gas sensor based on hollow nanosphere structures for H2S detection in aerospace environments

Abstract

Detecting hydrogen sulfide (H₂S) is crucial for aerospace applications, as it is commonly present in planetary soils. However, the vacuum conditions encountered in aerospace, characterized by ultra-low pressure and oxygen-deficient atmospheres, pose significant challenges for conventional sensors. In this paper, we report the design and fabrication of a ppb-level H₂S gas sensor based on hollow CuO–SnO₂ nanosphere structures (∼200 nm). Remarkably, the sensor achieves the reliable detection of H₂S at concentrations as low as 50 ppb, even under high-vacuum conditions (∼3 × 10⁻³ Pa). Moreover, it maintains stable sensing performance from room temperature (25 °C) to sub-zero environments (−40 °C), with responses of 464.6 and 3.9 toward 5 ppm H₂S, respectively. Unlike conventional sensors that rely on oxygen vacancies and require ambient oxygen to function, our sensor exploits a direct chemical reaction between CuO and H₂S, enabling efficient operation in oxygen-free vacuums. The hollow nanosphere architecture enhances gas adsorption, while a built-in p–n heterojunction provides charge modulation independent of oxygen. This synergistic structural and electronic design delivers ppb-level H₂S sensing under extreme vacuum conditions, positioning CuO–SnO₂ nanospheres as a versatile platform for gas sensing in both ambient and aerospace environments.