Highly Selective and ppb-Level Butanone Sensors Based on SnO2/NiO Heterojunction-Modified ZnO Nanosheets with Electron Polarity Transport Properties

Gas sensors require the construction of composites with high reactivity to reduce the detection limit, but this can lead to a broad-spectrum response between the adsorbed oxygen and the target gas, making it difficult to improve selectivity. In this study, the phenomenon of electron polar transport properties of the two-dimensional heterojunction material is first discovered in gas sensing and utilized to greatly improve the selectivity of butanone sensors. Ultra-thin porous ZnO nanosheets modified with SnO₂/NiO heterogeneous particles are synthesized to achieve 20 ppb detection limits for butanone with a response of 328 to 100 ppm butanone, which is the lowest known detection limit. The combination of reaction kinetics and liquid chromatography-mass spectrometry reveals a good synergistic catalytic effect of SnO₂/NiO heterogeneous particles, which may contribute to the high response and low detection limit of butanone. Finally, the possible mechanism for the generation of electron polar transport phenomenon is analyzed in the two-dimensional heterojunction material. This work provides a novel perspective for achieving both selectivity and detection limits in gas sensors, with universal applicability and application potential.