Tuning the sensing selectivity of mesoporous hierarchical Ti-doped Co3O4 to toluene and xylene via controlling the oxygen defects

Abstract

Vast efforts have been made to develop high-performance gas sensing materials for the detection of harmful volatile organic compounds (VOCs) like toluene and xylene. However, it is challenging to selectively detect toluene and xylene simultaneously. Herein, the hierarchical Ti-doped cobalt layered hydroxides miscrospheres were synthesized first and sintered at high temperature consequently to prepare hierarchical Ti-doped Co3O4 miscrospheres. The incorporation of Ti into the lattice of Co3O4 decreased the crystal sizes and crystallinity, resulting in higher specific surface area and more oxygen defects. Interestingly, the 3 at.% Ti-doped Co3O4 miscrospheres sintered at 450 °C exhibited the highest response of 64.9 to 50 ppm of xylene at 210 °C, while the 1 at.% Ti-doped Co3O4 miscrospheres calcined at 500 °C displayed the highest response of 57.2 to 50 ppm of toluene at 240 °C, which were about 11.8 and 7.8 times higher in comparison with pristine Co3O4. The different selectivity of Ti-doped Co3O4 to toluene and xylene arises from the different amounts of oxygen vacancies and defect oxygen ions. The obtained Ti-doped Co3O4 microspheres also showed the merits of good selectivity, repeatability and long-term stability, indicating the promising applications of Ti-doped Co3O4 miscrospheres in the detection of toluene and xylene.