Highly sensitive ammonia gas sensor based on metal-organic frameworks-derived CoSe2@nitrogen-doped amorphous carbon decorated with multi-walled carbon nanotubes

Abstract This paper presents a high-sensitivity ammonia (NH3) sensor based on nitrogen-doped amorphous carbon-coated cobalt diselenide and multi-walled carbon nanotubes-decorated nano-composite (CoSe2@NC/MWCNTs). In this study, nitrogen-doped amorphous carbon-coated cobalt diselenide (CoSe2@NC) was prepared from a cobalt-based metal-organic framework (MOF) and in situ selenization of cobalt ions. The prepared samples were characterized by all kinds of advanced techniques of SEM, TEM, XPS, XRD and BET. The CoSe2@NC/MWCNTs film was deposited on an epoxy substrate having interdigitated electrode microstructure. The NH3 sensing characteristics of the sensor were studied at room temperature (RT) of 25 oC and 43% relative humidity (RH). The response of the CoSe2@NC/MWCNTs-S2 sensor to 10 ppm NH3 is up to 93.37%, and the sensor can detect NH3 concentration as low as 0.1 ppm. In addition, the effect of humidity on sensor performance was also explored. This significant increase in gas sensing performance is primarily due to the synergistic effects of CoSe2@NC/MWCNTs composite and the effect of p-n heterojunction. The sensor proposed in this work is capable for the NH3 gas detection and human disease diagnosis.