In Situ Synthesis of Hierarchical Co(CO)(OH)·0.11HO@ZIF-67/WO With High Humidity Immunity and Response to HS Sensing.

HS gas sensors with facile preparation, low detection limits, and high selectivity are crucial for environmental and human health monitoring. However, it is difficult to maintain a high response of HS gas sensors under high humidity in practical applications. To face this dilemma, a layer-by-layer growth method is applied to in situ prepare a nanostructured Co(CO)(OH)·0.11HO/WO coated by a hydrophobic hierarchical ZIF-67 as the HS sensor. This novel composite exhibits excellent humidity immunity without sacrificing the excellent sensitivity and selectivity of HS. At a low operating temperature of 90 °C, a remarkable response value of 1052.3 to 100 ppm HS has been achieved, which is 779 and 9.36 times higher than that of pure WO and Co(CO)(OH)·0.11HO/WO, respectively. More importantly, an 82.2% relative response value remains at a high humidity of 75%RH. The sensing mechanisms are investigated using gas chromatography-mass spectrometry (GC-MS), which revealed that the reaction products are HO and SO. The high humidity immunity and fast response of the Co(CO)(OH)·0.11HO@ZIF-67/WO demonstrate the layer-by-layer in situ synthesis method holds the potential application for the development of high-performance WO-based HS sensors.