Nanomaterials - 07

Abstract

The sensing of volatile organic compounds (VOCs) is an important aspect of modern industrial processes including agriculture or food processing, medical engineering or clinical diagnostics, as well as in the production of green energy or for environmental monitoring. Two key elements of gas or VOC sensors are the transducer and the receptor layer, which together allow us to analyze different targeted analytes based on the generation of a measurable response. Sustainable development of gas or VOC sensors is possible only when we can improve the sensors characteristics in terms of “3S”: sensitivity, selectivity, and stability. Therefore, it is critical to develop novel classes of materials which are compatible with sensor platform to provide excellent sensitivity, selectivity, and stability. Porous substances such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs) and zeolites are important materials for gas or VOC sensing. However, those materials are not suitable for solution processing, one of the most challenging issues affecting the “3S” goal. Solution processing of small molecule precursors into useful porous architectures would be beneficial to overcome the post-synthesis solution processability issue. Here, we have developed a novel class of materials based on non-planar saddle-shaped N-heterocycle-fused metalloporphyrin, which forms a persistent microporous crystalline structure directly from solution.[1] These microporous crystalline structures with uniform porosity have been used as receptor materials for highly sensitive membrane-type surface stress sensor (MSS)2 to develop highly selective and sensitive gas or VOC sensor. These unique receptor materials show excellent performance under high humid (100 % RH) condition and can be used to discriminate different low concentrated targeted analytes from their mixtures. Additionally, fine tuning of functional groups of the metallo-porphyrin structure allows control of the receptor microporosity and the resulting sensor selectivity. Thus, we have developed a series of receptor materials which are highly porous, solution processable and ready to deposit on any suitable sensor platform for use as receptor materials for gas or VOC sensing.