Tailoring Oxygen Vacancy of Co<sub>3</sub>O<sub>4</sub> Microcubes by Annealing Co<sub>3</sub>[Co(CN)<sub>6</sub>]<sub>2</sub> Template in Air for Ultrasensitive Humidity Mapping
Haixia Yu, Chuanyu Guo, Xian‐Fa Zhang, Xiaoli Cheng, Yingming Xu, Shan Gao, Li-Hua Huo
Abstract
Improving sensitivity under low humidity is highly desirable for the applications of humidity sensors in robotics, intelligent prosthetics, and human–machine interfaces, etc. Herein, by using K 3 [Co(CN) 6 ] as a single‐source precursor, the Co 3 [Co(CN) 6 ] 2 microcubes were synthesized, which can keep the morphology in temperature range of 380–880 °C as annealed in air. Benefited from the ultrahigh structural stability of the Co 3 [Co(CN) 6 ] 2 , the oxygen vacancy in the derived Co 3 O 4 products can be controllably fabricated through altering calcination temperature. The oxygen vacancy‐abundant Co 3 O 4 products displayed significantly enhanced response under low humidity (0–6%RH), and thus were applied in scanning a series of water areas to map the humidity distribution. This work presents a promising strategy on rationally designing humidity sensing materials via oxygen defect engineering and provides more possibilities for the application of low‐cost humidity sensors in some emerging fields.