NH3 Sensor Based on 3D Hierarchical Flower-Shaped n-ZnO/p-NiO Heterostructures Yields Outstanding Sensing Capabilities at ppb Level. - Zhenting Zhao; Haoyue Yang; Zihan Wei; Yan Xue; Yongjiao Sun; Wenlei Zhang; Pengwei Li; Weiping Gong; Serge Zhuiykov; Jie Hu (Sensors, 2020)