Construction of heterojunction interface between SnO2 nanorods and MOF-derived Co3O4 nanoparticles fabricated via AACVD for H2 sensor

Metal-organic-framework (MOF)-derived oxide is a promising gas-sensing material candidate because of its high surface area, porosity and structural diversity. Utilizing Aerosol-assisted chemical vapor deposition (AACVD), the fabrication of MOF-derived films performs characteristic morphology and controlled size, which greatly improve the gas-sensing performance. Herein, the heterojunction interface between SnO 2 nanorods and MOF-derived Co 3 O 4 nanoparticles was prepared by two step AACVD. Firstly, SnO 2 nanorods were directly grown on flat electrode. Subsequently, size-controlled MOF-derived Co 3 O 4 nanoparticles were coated on SnO 2 nanorods. The hydrogen sensors were developed based on the above sensing materials with different deposition time ( 0, 30, 40 and 50 min) to demonstrate gas-sensing performance. The Co 3 O 4 /SnO 2 -40 sensor exhibits a response value of 305 % to 100 ppm of H 2 at 310°C, which is 4.4 times of the SnO 2 sensor. Moreover, the Co 3 O 4 /SnO 2 -40 sensor retains a measurable response of 4 % even at an extremely low hydrogen concentration of 200 ppb. The superior sensing performance of this sensor can be attributed to the large surface area and the p-n heterojunction interface. Consequently, the construction of heterojunction via AACVD offers an approach for fabricating high performance hydrogen sensors.