NiO nanoparticles‐decorated ZnO hierarchical structures for isopropanol gas sensing
Shi-Chao Wang, Xiaohu Wang, Gaoqun Qiao, Gao‐Qun Qiao, Xinzhen Wang, Nannan Wu, Jian Tian, Hongzhi Cui, Jian Tian, Hongzhi Cui
Abstract
Abstract In this paper, a three‐dimensional (3D) hierarchical ZnO structure consisting of nanosheets modified with ultrafine NiO particles was synthesized via a facile two‐step chemical precipitate method. Various techniques characterized the as‐synthesized ZnO/NiO composites and pure ZnO. The p‐NiO/n‐ZnO junctions formed between adjacent ZnO and NiO nanoparticles, improving the gas sensing performance. The ZnO/NiO composite with the Ni:Zn atomic ratio of 7.42:100 exhibited the best isopropanol sensing properties. Compared to pure ZnO, it showed high selectivity and sensitivity ( R a / R g = 221.3 toward 400 × isopropanol), fast response rate (less than 10 s), short recovery time, and simultaneously low operating temperature. Also, the ZnO/NiO composite exhibited a wide sensing range (1 × –1000 × ) to isopropanol and processed good long‐term stability. The experimental results suggested the potential application in fabricating efficient isopropanol sensors using this ZnO/NiO composite. The enhanced isopropanol sensing mechanism is also discussed in charge transfer between heterojunctions, surface area, and surface defects.