Sb-Doped SnO₂ Hollow Spheres for Low-Resistance and Highly Selective Xylene Sensors

It is important to be able to detect xylene with high selectivity and low sensor resistance when monitoring indoor and outdoor air quality. In this study, we report the development of Sb-doped SnO₂ hollow spheres synthesized via ultrasonic spray pyrolysis for high-performance xylene detection with significantly reduced sensor resistance. The 2 mol% Sb-doped SnO₂ sensor exhibited a remarkably high response (S_X = 24.0) and selectivity (S_X/S_E = 3.4) toward 5 ppm xylene at 300 °C. Notably, the sensor resistance in air (R_a) was reduced by ~200-fold compared to that of pure SnO₂, reaching a practical level of 38.5 kΩ, which enables cost-effective signal measurement. Furthermore, the 2Sb-SnO₂ sensor demonstrated a low detection limit of 50 ppb and rapid response times (4-5 s). These results suggest that Sb doping is a highly effective strategy for engineering low-resistance and highly selective SnO₂ gas sensors. This study could pave the way for a practical approach to designing xylene detection systems for indoor air monitoring.