Study of the structural evolution and gas sensing properties of PECVD-synthesized graphene nanowalls

Abstract

This research paper reports on studies of the structural evaluation and room temperature ammonia (NH3) gas sensing properties of the 3D graphene nanowalls (GNWs). Large-area porous GNWs as sensing layers were directly prepared by using plasma enhanced chemical vapor deposition (PECVD) technique with the H2/CH4 gas mixture as a precursor. The H2 plasma etching not only contributes to the structural evolution and thickness of the maze-liked nanowalls, but also plays important roles on the defect sites of the surface and effective crystalline size of the PECVD-synthesized GNWs. The comparative studies of sensing performances show the newly fabricated GNWs sensors were highly responsive and selective to NH3 gas with low detection limit at room temperature. Charge transfer has been confirmed as the dominant sensing mechanism for the GNWs sensors. The excellent sensing performances of the GNWs demonstrate the 3D assemblies of 2D graphene nanosheet structures with high surface area, a large amount of defect sites and small crystalline sizes are promising candidate for gas sensing applications.