NO2 gas sensor with high selectivity and fast response based on Pt-loaded nano-porous GaN

In this work, we realized a room-temperature NO2 gas sensor based on the Pt-loaded nano-porous GaN sensing material by thermal reduction method and co-reduction with the catalyzing of polyols. The gas sensor gained excellent sensitivity to NO2 of concentration range from 200 ppm to 100 ppb benefiting from the loading of Pt nano-particles, exhibited short response time (22 s) and recovery time (170 s) to 100 ppm NO2 at room temperature with excellent selectivity to NO2 compared to other gases. This phenomenon is attributed to the spillover effect and the synergic electronic interaction with semiconductor materials of Pt which not only provided more electrons for the adsorption of NO2 molecules but also occupied effective sites causing the poor sites for other gases. The low detection limit of Pt/NP-GaN is 100 ppb and the gas sensor still had fast response 70 days after fabrication. Besides, the gas sensing mechanism of gas sensor is further elaborated to figure out the reason leading to the improvement of properties. The significant spillover impact and oxygen dissociation of Pt provided advantages to its synergic electronic interaction with semiconductor materials leading to the development of gas properties of gas sensors.