Hierarchical heterostructures of nanosheet-assembled NiO-modified ZnO microflowers for high performance acetylene detection

It is of great significance to monitor internal faults of transformer and ensure its normal and safe operation. Usually, acetylene (C2H2) is considered as the characteristic gas caused by discharge failure in transformer. Using gas sensor technology to analyze dissolved gases in transformer oil is an important strategy. Recently, metal oxide semiconductor (MOS) heterojunctions with tailored microstructures have been developed to fabricate high quality gas sensors for gas detection. In this paper, hierarchical flower-like NiO/ZnO heterostructures assembled with 2D nanosheets have been synthesized by a facile hydrothermal method and calcination process. Noticeably, the introduction of different contents of NiO (3.0 at%, 5.0 at% and 10.0 at%) leads to different assembly manners of the building nanosheets into hierarchical flower-like structures, thus affecting the gas performances. Given this, a variety of microscopic characterization methods were used to observe and compare the differences in the structures and morphologies of the composites. Through the gas sensing test, it was found that the 5.0 at% Ni0-modified ZnO based sensor exhibited superior sensing performances to C2H2 compared with that of others. The enhanced properties may be attributed to the formation of p-n heterojunctions as well as high porosity of the nanosheets. This promising approach is versatile for the applications of high-quality gas sensors.