Metastable Antimony‐Doped SnO2 Quantum Wires for Ultrasensitive Gas Sensors

Abstract Doping is fundamental to controlling the properties of bulk semiconductors. Although the antimony (Sb V )‐doping strategy is widely employed in the design of practical tin oxide (SnO 2 ) semiconductor gas sensors for higher signal‐to‐noise ratio, challenges remain to dope semiconductor nanocrystals since the diffusion of impurity atoms may be far from realized at the synthesis temperatures used. Herein, a metastable Sb‐doping strategy is proposed to overcome the serious receptor‐versus‐transducer mismatch in SnO 2 quantum wires (QWs). The solvothermal synthesis of colloidal Sb III ‐doped SnO 2 QWs has been conducted at 180 °C, whereby the antimony amount is varied to optimize the structural and morphological properties for higher surface activity and electrical conductivity. A unique n‐type doping mechanism arising from the stable presence of Sb III on SnO 2 (101) facets via Sn II ‐O‐Sb III is demonstrated. Further, the use of sensitive (down to 4 ppb, the lowest detection limit ever reported), fast (response and recovery time of 43 s and 96 s toward 10 ppm of H 2 S) gas sensors for H 2 S detection at near room temperature (40 °C) is showcased. The metastable Sb‐doping strategy may pave the way to ultrasensitive gas sensor possessing low power consumption and excellent integration compatibility to satisfy the increasing demand for ubiquitous and reliable gas detection.