Tunable oxygen vacancies of cobalt oxides for efficient gas sensing application

It is a big challenge to apply p-type metal oxide semiconductors for gas sensing. This study presents an efficient and rapid approach to detect triethylamine (TEA) by newly generated p-type Co3O4 nanosheets with rich oxygen vacancies. These porous Co3O4 nanosheets were synthesized via a simple but efficient hydrothermal method, followed by annealing process. The defect concentration, highly related to the morphology of the obtained sensing materials, was readily adjustable by controlling annealing temperature. It was found that the presence of abundant oxygen vacancies and the large specific surface area have synergistically promoted gas sensing performance using Co3O4 nanosheets in detecting TEA with a sensitive response (Sg/a = 124.36 for 100 ppm TEA) at an operating temperature (200 °C). Furthermore, the Co3O4 nanosheets have exhibited excellent selectivity, repeatability and stability, probably attributed to the formation of mesoporous structures and appropriate oxygen vacancy concentrations. This work may offer an effective path for designing p-type metal oxide semiconductor nanomaterials for gas sensing applications by controlling oxygen vacancies and particle morphologies.