▎ 摘　　要

We report a new hybrid sensor in which an ultrathin polypyrrole (PPy) layer is deposited on the CVD-grown graphene (G) by electropolymerization. The sensor exhibits an excellent performance in the selective sensing of ammonia (NH3) at room temperature, having a high, fast, and reversible response. It also shows rather good stability, reproducibility, and immunity to humidity. These performances are attributed to the synergistic effect between the PPy layer and G. Specifically, the NH3 molecules are adsorbed on the PPy layer, electrons transfer from NH3 to the PPy layer, changing the PPy layer resistance. Electrons can also be transferred to the G through the ultrathin PPy layer, in certain way changing the G resistance. These promote the sensor sensitivity. Moreover, the ultrathin PPy layer with porous nature plays an important role in the sensor response, selectivity, and immunity to humidity. Graphene is not only a support material for PPy electropolymerization but also provides an efficient pathway for electron transfer, thereby, accelerating the sensor response and recovery. Our research indicates that the combination of PPy and C is a very promising as a chemical sensor material. We implement a smart prototype with the present sensor in an electronic board for real-time monitoring the NH3 concentrations. The smart prototype can be connected to a computer by a USB port for demonstrating NH3 concentrations, transmitting the data and analyzing the sensor response curves. Our results are beneficial forward the commercial design and fabrication of sensors fulfilling the specifications of practical applications.