Pt nanoparticle decoration on femtosecond laser-irradiated SnO₂ nanowires for enhancing C₇H₈ gas sensing

In this study, we have fabricated a sensitive and selective toluene gas sensor based on SnO₂ nanowires (NWs) using the femtosecond (FS) laser irradiation and Pt nanoparticle (NPs) decoration. The effects of different laser parameters, including wavelength, laser pulse energy, hatch distance, and scan speed, are investigated on the gas-sensing properties. The FS laser irradiation-induced embossing surface is found to be a dominant factor in determining the gas-sensing behavior, which provides more oxygen absorption sites, resulting in an increase in the width of the electron depletion layer (EDL) and the sensor response. The Pt decoration on the FS laser-irradiated SnO₂ NWs developed additional EDL, which further enhances the sensor response. The Pt-decorated and FS laser-irradiated SnO₂ NWs gas sensor shows a high selectivity toward C₇H₈ owing to the catalytic effect of Pt toward toluene, where the sensor response to 50 ppm C₇H₈ is as high as 53 at 300 °C. Based on X-ray photoelectron spectroscopy and transmission electron microscopy analyses, a gas-sensing mechanism of the Pt-decorated and FS laser-irradiated SnO₂ NWs gas sensor is proposed. This study highlights a promising combination of Pt decoration and FS laser irradiation for the realization of reliable toluene gas sensors.