Synthesis of novel BiVO/CuO heterojunctions for improving BiVO towards NO sensing properties.

To develop a high sensitive and low temperature NO gas sensor, the novel BiVO/CuO heterojunctions were synthesized by a modified metal organic decomposition method to decorate BiVO nanoplates using CuO nanoparticles for enhancement of BiVO sensing performance to NO The structure and morphology of BiVO, CuO and BiVO/CuO composites were characterized by XRD, SEM and TEM spectra. The results indicate that the BiVO/CuO heterojunctions are composed of monoclinic BiVO nanoplates with the thickness about 1.0-1.2 μm and 30-40 nm diameters of cubic CuO nanoparticles. The gas-sensing tests display that the composite exhibits rapid and linear responses to low concentration NO (from 100 ppb to 8.0 ppm), the highest response reaches 4.2 towards 4 ppm NO at 60 °C and relative humidity of 28.3%, which is more than 2 times of pure BiVO at the same condition. The enhanced sensing properties benefit from the novel p-n heterojunction between BiVO and CuO, which forms a depletion layer at the interface, leading to resistance increase of composites in NO. The work demonstrates the as-synthesized BiVO/CuO is a promising sensing material to detect NO gas.