In Situ Synthesis of Hierarchical Co(CO3)0.5(OH)·0.11H2O@ZIF‐67/WO3 With High Humidity Immunity and Response to H2S Sensing

Abstract

Abstract H2S 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 H2S 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(CO3)0.5(OH)·0.11H2O/WO3 coated by a hydrophobic hierarchical ZIF‐67 as the H2S sensor. This novel composite exhibits excellent humidity immunity without sacrificing the excellent sensitivity and selectivity of H2S. At a low operating temperature of 90 °C, a remarkable response value of 1052.3 to 100 ppm H2S has been achieved, which is 779 and 9.36 times higher than that of pure WO3 and Co(CO3)0.5(OH)·0.11H2O/WO3, 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 H2O and SO2. The high humidity immunity and fast response of the Co(CO3)0.5(OH)·0.11H2O@ZIF‐67/WO3 demonstrate the layer‐by‐layer in situ synthesis method holds the potential application for the development of high‐performance WO3‐based H2S sensors.

Keywords

• Co(CO3)0.5(OH)·0.11H2O@ZIF‐67/WO3
• gas‐sensing
• H2S
• in situ growth
• mechanism analysis