Effect of Open Metal Sites in Cobalt-Based Bimetallic Metal–Organic Framework Nanoparticles-Coated Quartz Crystal Microbalance (QCM) for Humidity Detection
Dan Zhang, Na Luo, Zhenggang Xue, Yue‐Ling Bai, Jiaqiang Xu
Abstract
As one of the most important environmental parameters, humidity always affects people’s life. It is still a challenge in attaining precise humidity sensors with a rapid and convenient method. Herein, cobalt-based bimetallic zeolitic imidazolate frameworks (ZIFs) nanomaterials were obtained by a facile solution precipitation method and applied for quartz crystal microbalance (QCM) sensors to measure relative humidity (RH) at room temperature. The characterization and sensing results show that ZIF-67 and ZIF-CoX (X = Ni, Cu, Zn) samples possess well-defined polyhedron, and the sensor based on ZIF-CoNi exhibits satisfactory sensitivity (6.10 Hz/%RH, at 97% RH), short response/recovery time (3/3 s, at 97% RH), and narrow hysteresis in the range 11%–97% RH compared with that of ZIF-67, while ZIF-CoCu and ZIF-CoZn have poor sensitivity. Finally, the humidity sensing mechanism was explored by wetting behaviors and FT-IR. Such a comprehensive research provides valuable information for the fast detection of humidity.