Solution-processed metal doping of sub-3 nm SnO2 quantum wires for enhanced H2S sensing at low temperature

Abstract

Doping a foreign atom into metal oxides enables the modulations of the electronic and chemical properties of active sites. SnO₂ quantum wires (QWs) possessing large surface area with highly exposed active sites have been demonstrated as promising sensing materials in gas sensors but they still suffer from unsatisfactory selectivity and limits of detection (LODs). Herein, we realize the electronic interaction of transition metal atoms (Cr, Mo, and W) and sub-3 nm ultrathin SnO₂ QWs using a general one-step solution process at low temperature (180 °C). Density functional theory calculations reveal that such tailored electronic structures reduce energy barriers for adsorption of gas molecules and transportation of electrons, which facilitates oxygen adsorption and activation, and thus accelerates surface reaction kinetics with H₂S molecules. Our results indicate that transition metal doping induces more oxygen vacancies (V_O) that lead to boosted H₂S chemical-sensing performances. Representative W-doped SnO₂ QWs (W–SnO₂) achieve enhanced low-temperature H₂S-sensing properties with a record LOD of down to 0.48 ppb, which surpasses most of the reported metal oxide-based gas sensors.