SnO2 quantum dot decoration of CuO nanoparticles with enhanced NO2 and H2 gas sensing response p–n heterojunction interfaces

Design and fabrication of heterostructures has emerged as a powerful strategy to improve gas sensing performances compared to single materials counterparts. In this work, we report an innovative CuO-based nanostructure decorated with SnO2 quantum dots (QDs) for the detection of NO2 and H2 gases. Here, CuO serves as the base material while SnO2 QDs are used as the decorating phase: an inversion of the conventional architecture where SnO2 is typically the host and CuO the modifier. The composite exhibits higher sensitivity compared to pristine CuO and SnO2, showing state-of-the-art performances in terms of relative responses (RRs) in the 20 ppb to 1 ppm range and 10 ppm to 250 ppm for NO2 and H2 respectively, with excellent stability and reproducibility. Moreover, the SnO2-QDs/CuO operates at a low working temperature (i.e. 100 degrees C), offering significant advantages in terms of energy efficiency and material stability. The observed enhancements are attributed to the optimized heterointerface, increased active surface area, and modulation of the charge carrier induced by the p-n heterojunctions. These results highlight the potential of reverse-configured SnO2/CuO as a versatile platform for improved, low-temperature gas sensors with high sensitivity.