Synthesis and application of graphene-silver nanowires composite for ammonia gas sensing

• Published in: Advances in natural sciences. Nanoscience and nanotechnology Vol. 4; no. 4; pp. 45012 - 5
• Main Authors: Tran, Quang Trung, Huynh, Tran My Hoa, Tong, Duc Tai, Tran, Van Tam, Nguyen, Nang Dinh
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.12.2013
• Subjects: ammonia gas sensing; Devices; Electrodes; Gas sensors; Graphene; Hummers method; Nanostructure; Nanowires; polyol method; Silver; silver nanowires; Synthesis
• ISSN: 2043-6262; 2043-6254; 2043-6254; 2043-6262
• DOI: 10.1088/2043-6262/4/4/045012

Graphene, consisting of a single carbon layer in a two-dimensional (2D) lattice, has been a promising material for application to nanoelectrical devices in recent years. In this study we report the development of a useful ammonia (NH3) gas sensor based on graphene-silver nanowires 'composite' with planar electrode structure. The basic strategy involves three steps: (i) preparation of graphene oxide (GO) by modified Hummers method; (ii) synthesis of silver nanowires by polyol method; and (iii) preparation of graphene and silver nanowires on two electrodes using spin and spray-coating of precursor solutions, respectively. Exposure of this sensor to NH3 induces a reversible resistance change at room temperature that is as large as ΔR R0 ∼ 28% and this sensitivity is eight times larger than the sensitivity of the 'intrinsic' graphene based NH3 gas sensor (ΔR R0 ∼ 3,5%). Their responses and the recovery times go down to ∼200 and ∼60 s, respectively. Because graphene synthesized by chemical methods has many defects and small sheets, it cannot be perfectly used for gas sensor or for nanoelectrical devices. The silver nanowires are applied to play the role of small bridges connecting many graphene islands together to improve electrical properties of graphene/silver nanowires composite and result in higher NH3 gas sensitivity.