Phosphorus doping of graphene for conductometric room temperature ammonia sensing

Abstract

The ammonia (NH 3 )-sensing performance of phosphorus-doped graphene sensors is systematically investigated in this paper. Using a chemical vapor deposition (CVD) system, phosphorus pentoxide was used as the phosphorus source to achieve stable phosphorus doping of graphene at 480 o C. The NH 3 -sensing test results showed that the NH 3 response of phosphorus-doped graphene increased by 2.4 times on average, the response (recovery) time shortened by 70.6% (73.4%) on average, and the theoretical limit of detection (LOD) was 68.76 ppb. In addition, the phosphorus-doped graphene sensor also exhibits excellent repeatability, stability, and ultra-high selectivity to NH 3 . XPS, EDS, and FTIR analysis show that the P-O groups introduced on graphene are the key to improving the NH 3 sensitivity of graphene. The P-O groups provide sufficient O atoms to assist graphene to adsorb NH 3 molecules, thereby improving the NH 3 sensitivity of graphene. A simple, large-scale implementable, and effective phosphorus doping by the CVD method was proposed to improve the NH 3 sensitivity of graphene in this work, which is of great significance for promoting the practical application of graphene gas sensors. • After phosphorus doping, the NH 3 response of graphene sensor increased by 2.4 times. • The detection limit of the phosphorus-doped graphene sensor towards NH 3 is 69 ppb. • The response time of phosphorus-doped graphene sensor shortened by 70.6%. • Low-cost and stable phosphorus doping of graphene is achieved at 480 °C by CVD.