MOF (metal-organic framework) nanomaterial for 400ppb-concentration detectable xylene gas sensors

In this paper, metal-organic framework (MOF) is explored as xylene sensing-material for resonant-cantilever gas sensor. Sensing experiment with the MOF nano-material of HKUST-1 demonstrates that 400 ppb xylene can be detected. This limit of detection (LOD) has been lower than the human olfactory threshold. The sensing mechanism is identified as the interaction between MOF and xylene. The specificity of HKUST-1 MOF to xylene is originated from the Cu²⁺ induced moderate Lewis acidity and like-dissolves-like interaction of benzene-ring.

Introduction

Nowadays, xylene is frequently used in many daily products in people's lives everywhere like various coatings, paints and adhesives, since xylene is an important organic chemical and widely used as solvent. However, as one of typical VOCs (volatile organic compounds), xylene is harmful for human's health because it significantly inhibited the activities of cellular antioxidant enzymes such as superoxide dismutase (SOD), guaiacol peroxidase (POD) and catalase (CAT) in human body [1]. Thus, it is really important for us to pay more attention on the toxic of xylene, especially in the indoor air. Although xylene has a pungent odour at high concentration, it is still difficult for us to directly smell xylene in the indoor atmosphere because the concentration of ambient xylene is usually below the olfactory threshold of human beings of 0.47 ppm (parts per million by volume) [2].