Sensitive hydrogen sensing using SnO2 enabled by single-layer graphene composites

Developing high-performance sensors for the rapid and reliable detection of hydrogen in the air is crucial. In this study, a hydrogen sensor utilizing a single-layer graphene/SnO₂ composite was synthesized via the hydrothermal method. The investigation focused on assessing the impact of varying doping levels of single-layer graphene (SLG) on the hydrogen-sensing capabilities of the SnO₂ base material. The results indicated that optimal performance was achieved with an SLG doping of 4 mg. The SnO₂/SLG-4 mg material exhibited its best response at a temperature of 250 °C, with a response value of 1.98 for 10 ppm of hydrogen, and a response/recovery time of 1.32/3.54 s. The sensing mechanism of the single-layer graphene/SnO₂ composite sensor is attributed to the SLG doping, which facilitates the formation of an n-p heterojunction structure on the surface of the SnO₂ grains. This structure increases the electron concentration; SLG doping also contributes to grain refinement. Analysis from X-ray photoelectron spectroscopy (XPS) revealed that SLG doping enhances the concentration of oxygen vacancies, increasing the number of active sites on the material's surface, thereby optimizing its hydrogen-sensing capabilities. This method of doping single-layer graphene provides a new idea and method for the preparation of low detection limit gas sensors.