Low-Temperature H₂S Detection with Hierarchical Cr-Doped WO₃ Microspheres

Hierarchical Cr-doped WO₃ microspheres have been successfully synthesized for efficient sensing of H₂S gas at low temperatures. The hierarchical structures provide an effective gas diffusion path via well-aligned micro-, meso-, and macroporous architectures, resulting in significant enhancement in sensing response to H₂S. The temperature and gas concentration dependence on the sensing properties elucidate that Cr dopants remarkably improve the response and lower the sensor’ operating temperature down to 80 °C. Under 0.1 vol % H₂S, the response of Cr-doped WO₃ sensor is 6 times larger than pristine WO₃ sensor at 80 °C. We suggest the increasing number of oxygen vacancies created by Cr dopants to be the underlying reason for enhancement of charge carrier density and accelerated reactions with H₂S.