Naphthacene-Based Two-Dimensional Conductive Metal-Organic Framework for Highly Efficient Chemiresistive Sensing of Ammonia

Abstract

Two-dimensional conductive metal-organic frameworks (MOFs) emerge as a group of promising materials for chemiresistive sensing, however, still face challenges of balancing high sensitivity and quick response/recovery kinetic. This study demonstrates the development of a highly efficient gas sensor for ammonia (NH3) detection using a naphthacene-based conductive MOF synthesized by interconnecting Cu ions and a specially designed organic ligand, octahydroxyl tetrabenzonaphthacene (OHTBN). The resulting MOF Cu-OHTBN with high crystallinity exhibits a high surface area of 307 m2 g−1 and unique semiconductive property of a low band structure bandgap of 0.064 eV and a moderately high room-temperature conductivity of 2.35 × 10−3 S cm−1. When integrated into chemiresistive devices, Cu-OHTBN exhibits good linearity to 2-80 ppm of NH3 and remarkable sensitivity with low experimental detection limits of 0.061 ppm, meanwhile giving excellent sensing dynamic with short response times of 0.52 min (80 ppm NH3) at room temperature. The sensing performance is superior to most other 2D conductive MOF currently used for NH3 sensing. Mechanistic study combing DRIFTS and DFT calculations shows that the key for high sensitivity and quick sensing kinetic is the electron perturbation of the whole plane caused by adsorption of NH3 with MOF.