Sensors and Actuators B 163 (2012) 107–114 Contents lists available at SciVerse ScienceDirect Sensors and Actuators B: Chemical journa l h o mepage: www.elsevier.com/locate/snb Gas sensor based on p-phenylenediamine reduced graphene oxide Nantao Hu a , Yanyan Wang b,∗ , Jing Chai a , Rungang Gao a , Zhi Yang a , Eric Siu-Wai Kong a , Yafei Zhang a a Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nanometer Science & Technology, Shanghai Jiao Tong University, Shanghai 200240, PR China b Institute of Information Optical Engineering, Soochow University, Suzhou 215006, PR China a r t i c l e i n f o Article history: Received 19 August 2011 Received in revised form 4 January 2012 Accepted 5 January 2012 Available online 25 January 2012 Keywords: Graphene p-Phenylenediamine Drop drying DMMP Gas sensor a b s t r a c t We present a useful gas sensor based on chemically reduced graphene oxide (CRG) by drop drying method to create conductive networks between interdigitated electrode arrays. CRG, which is formed from the reduction of graphene oxide by p-phenylenediamine (PPD), can be used as an excellent sensing mate- rial. Its efficient dispersion in organic solvents (i.e., ethanol) benefits the formation of conductive circuits between electrode arrays through drop drying method. Preliminary results, which have been presented on the detection of dimethyl methylphosphonate (DMMP) using this simple and scalable fabrication method for practical devices, suggest that PPD reduced CRG exhibits much better (5.7 times with the concentration of DMMP at 30 ppm) response to DMMP than that of CRG reduced from hydrazine. Fur- thermore, this novel gas sensor based on CRG reduced from PPD shows excellent responsive repeatability to DMMP. Overall, the efficient dispersibility of CRG reduced from PPD in organic solvents facilitates the device fabrication through drop drying method, the resultant CRG-based sensing devices, with miniature, low cost, portable characteristics, as well as outstanding sensing performances, can ensure its potential application in gas sensing fields. © 2012 Elsevier B.V. All rights reserved. 1. Introduction With the development of sensing technology in many fields, including environment monitoring, industry and agriculture pro- duction, medical diagnosis, military and public safety, etc., chemiresistive sensors play more and more important roles, due to their low power consumption and the ease of high precision resistance measurements [1–5]. Many sensing materials, including semi-conducting metal oxide [6], organic semiconductors [7], car- bon nanotubes (CNTs) [8], etc., have been used for chemiresistive sensors and exhibit great potential for gas sensing applications. As a nanometer-thick two-dimensional analog of CNTs, graphene has emerged as another promising candidate for sens- ing, owing to its exceptional electronic, mechanical, chemical, and thermal properties [9–15]. Similar with CNTs, the high fraction of surface atoms in graphene makes this carbon nanosheet an ideal candidate for sensing applications. Since Novoselov et al. [16] firstly demonstrated the gas sensing potential of graphene through exposure of the devices to water, ethanol vapors, or ammonia gas, many research papers focused on this topic emerged [17–20]. It has been demonstrated that excellent sensing performance of graphene toward NO 2 , NH 3 , H 2 O, CO, trimethylamine, I 2 , ethanol, ∗ Corresponding authors. E-mail addresses: hunantao@sjtu.edu.cn (N. Hu), yywang@suda.edu.cn (Y. Wang), yfzhang@sjtu.edu.cn (Y. Zhang). HCN, dimethyl methylphosphonate (DMMP), DNT, etc., could be achieved [17–22]. Several methods, including micromechanical exfoliation of graphite [16], chemical vapor deposition [23], and solution-based chemical reduction of graphene oxide (GO) [24], have been developed to prepare graphene nanosheets and hold great potential for gas sensing applications. Among, chemically reduced graphene oxide (CRG), which is synthesized by the chem- ical reduction of GO, has been aroused much attention for using as chemiresistors [25–29], due to its scalable production, solution processibility, large available surface area, etc. Chemical reduc- tion of GO by hydrazine has been successfully achieved through elimination of oxygen-containing groups, and the resultant CRG exhibits a substantially rapid electrical response to many gases or vapors [18,25]. Ruoff group [30] has reported an all-organic vapor sensor based on CRG, which is synthesized by the reduction of GO using ascorbic acid as a mild and green reducing agent. The resultant rugged and flexible sensor using inkjet-printed films of CRG on poly(ethylene terephthalate) can reversibly detect NO 2 and Cl 2 vapors in air at ppb level. Although many reports have been reported on the sensing properties of CRG, it is still a great chal- lenge to develop the sensing devices based on CRG with miniature, low cost and portable characteristics. Herein, we have reported for the first time that CRG reduced from p-phenylenediamine (PPD) could be used as an excellent sensing material. Sensing devices can be easily fabricated through using drop drying method to create conductive CRG networks between interdigitated electrode arrays. The DMMP gas sensing 0925-4005/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2012.01.016