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

[Display omitted] Highly sensitive and selective NO2 sensor for ppb-level detection at room temperature was constructed using MOF-derived Cu2O–CuO octahedrons as sensing material. •Cu2O–CuO octahedrons were fabricated by the thermal decomposition of Cu-based MOFs.•Cu2O–CuO p–p heterojunctions were formed in the octahedrons.•Cu2O–CuO octahedrons showed an increased surface O2- species absorbing capability.•Cu2O–CuO exhibited sensitive and selective detection of ppb-level NO2 at 25 °C.•The gas-sensing enhancement mechanism of Cu2O–CuO octahedrons was proposed. Cu2O–CuO heterojunction octahedrons were fabricated by the thermal decomposition of Cu-based metal–organic framework (MOF) precursors. The adsorbed oxygen species (O2-) 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 °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 O2- 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.