Convenient detection of H2S based on the photothermal effect of Au@Ag nanocubes using a handheld thermometer as readout

Highlights: • A simple and sensitive photothermal assay is developed for quantitative detection of H₂S. • The photothermal conversion properties of Au@Ag nanocube can be changed by the addition of H₂S. • The molecular detection can be translated into a simple temperature test. • This method can be applied to detect H₂S around dumps with a simple sample pretreatment. Hydrogen sulfide (H₂S), as a hazardous gas, is often found around dump areas. Long term exposure can cause harm to health, it is highly necessary to develop some simple and sensitive methods for on-site H₂S detection. Herein, a convenient photothermal assay has been designed for the quantitation of H₂S using a handheld thermometer as readout. Au@Ag nanocubes (Au@Ag NCs), a core-shell nanocomposite with strong light absorption at ∼450 nm, was chosen as a novel photothermal agent in this study. Under the laser irradiation at 450 nm, the Au@Ag NCs show a strong photothermal effect, and a significant temperature enhancement can be measured by the thermometer easily. The presence of H₂S can lead to the deposition of sulfur onto Au@Ag NCs, altering the localized surface plasmon resonance absorption, size, surface composition, and morphology of Au@Ag NCs and hence leading to the reduction of photothermal effect. The change of the temperature has a linear relationship with the H₂S concentration in the range of 0.5–80.0 μM with a detection limit of 0.35 μM. By combining with simple sample purification procedures, the developed method has been applied to detect H₂S in garbage odor gas with satisfactory results.