Metal-organic framework-derived Cu₂O-CuO octahedrons for sensitive and selective detection of ppb-level NO₂ at room temperature

Cu2O-CuO heterojunction octahedrons were fabricated by the thermal decomposition of Cu-based metal-organic framework (MOF) precursors. The adsorbed oxygen species (O-2(-)) content was visibly increased by constructing such kind of p-p heterojunctions. Compared with commercial CuO powder, this kind of Cu2O-CuO octahedrons exhibited much better sensing properties to NO2. At room temperature (RT, 25 degrees C), the Cu2O-CuO octahedrons showed a higher response, reaching 8.25-500 ppb NO2, which was 2.88 times higher than that of CuO powder. Besides good NO2 stability and selectivity, a low detection concentration down to 10 ppb was also revealed at RT for the Cu2O-CuO octahedrons. From our perspective, the enhanced NO2 sensing properties of the Cu2O-CuO octahedrons can be mainly attributed to the formation of Cu2O-CuO p-p heterojunctions, facilitating the adsorption of more O-2(-) species to participate in the sensing reaction. The results here demonstrated that MOF-derived Cu2O-CuO octahedrons with a p-p heterojunction construction had a good potential for sensitive and selective detection of ppb-level NO2 at RT.