Study on NO2 gas sensitivity of metal phthalocyanine enhanced by graphene quantum dots

Abstract

Traditional semiconductor gas sensors mainly based on metal oxides have some problems such as high working temperature, high energy consumption, low sensitivity, poor anti-interference ability and poor selectivity. Organic semiconductors, represented by metal phthalocyanine (MPc), are becoming the choice of new semiconductor gas sensors because of their advantages of abundant raw materials, low cost, simple process, strong compatibility and ability to work at room temperature. In this study, metal phthalocyanine (molecular diameter of about 1.3 nm) and graphene quantum dots (diameter distribution of 1-3 nm) are similar in size, which facilitates the construction of conjugated plane structure to achieve rapid charge transfer within the material, thus realizing the ultra-sensitive response of the sensor to specific gas molecules at room temperature. In this work, ethylenediamine was used as adhesive to bond tetracarboxylic metal phthalocyanine (MPc-COOH) and graphene quantum dots (GQDs) to form a new composite material MPc-GQD. The response value of the sensor to 100 ppm NO2 gas can reach 19.8 in 100 s at room temperature, and it has good recovery and repeatability under the premise of laser-assisted recovery. The results provide a new idea for the development of room temperature gas sensors using organic semiconductors and carbon nanomaterials.