Metastable Antimony‐Doped SnO2 Quantum Wires for Ultrasensitive Gas Sensors

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 (SnO2) 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 SnO2 quantum wires (QWs). The solvothermal synthesis of colloidal Sb-III-doped SnO2 QWs has been conducted at 180 degrees 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 SnO2 (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 H2S) gas sensors for H2S detection at near room temperature (40 degrees 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.