Electrochimica Acta 116 (2014) 504–511 Contents lists available at ScienceDirect Electrochimica Acta jou rn al hom ep age: www.elsevier.com/locate/elec tacta (4-Ferrocenylethyne) Phenylamine Functionalized Graphene Oxide Modified Electrode for Sensitive Nitrite Sensing Meiling Liu, Linping Wang 1 , Yue Meng, Qiong Chen, Haitao Li, Youyu Zhang ∗ , Shouzhuo Yao Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, PR China a r t i c l e i n f o Article history: Received 24 July 2013 Received in revised form 1 November 2013 Accepted 11 November 2013 Available online 23 November 2013 Keywords: (4-ferrocenylethyne) phenylamine Functionalization of graphene oxide Nitrite detection a b s t r a c t In this paper, a new electron mediator modified graphene oxide (GO) was firstly prepared by covalently grafted (4-ferrocenylethyne) phenylamine (FEPA) onto the surface of GO. The successful attachment of FEPA onto GO sheets was demonstrated by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis spectroscopy, thermogravimetric analysis (TGA) and electrochem- ical experiments. The as prepared FEPA modified GO (FEPA-GO) proved to be a novel hybrid composite with highly enhanced conductivity and compatibility. Combined the FEPA-GO with chitosan (CS) to fab- ricate the modified glassy carbon electrode (GCE), a highly sensitive amperometric nitrite sensor was successfully constructed. The electrochemical oxidation current of nitrite on the CS/FEPA-GO/GCE was largely enhanced, which may result from the catalysis effect of the FEPA-GO. With this novel sensor, the oxidation peak currents were linearly dependent on the nitrite concentrations in the range of 0.3- 3100 mol L -1 with the detection limit of 0.1 mol L -1 . Modification of FEPA on GO held great promise to enhance the electrochemical performance of GO and will pay a new way for fabricating newly ferrocene functionalized graphene-based electrochemical biosensors. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction Nitrite is a well-known alarming pollutant in our daily life because it is widely used as an additive and corrosion inhibitor in food and environmental systems [1–3]. It is reported that nitrite can interact with amines to form carcinogenic nitrosamines [4]. Consid- ering the potential toxicity of nitrite, the sensitive determination of it is very important for environmental protection and public health [5–7]. Many techniques have been utilized to determine nitrite, such as chromatography [8], chemiluminescence [9], spectropho- tometry [10] and electrochemistry methods [11]. Among these techniques, electrochemical technique exhibits many advantages such as rapid responses, operational simplicity, low cost and high sensitivity [12]. Most electrochemical methods are based on the reduction of nitrite and these methods are subject to several inter- ferences, especially nitrate ion. Compared with the reduction of nitrite, the determination of nitrite by electrochemical oxidation shows significant advantage in anti-interferences due to the oxida- tion product was nitrate. However, the oxidation of nitrite involves ∗ Corresponding author. Tel.: +86 731 8865515; fax: +86 731 8865515. E-mail address: zhangyy@hunnu.edu.cn (Y. Zhang). 1 Linping Wang and the first author made equal contributions to this work a relatively higher overpotential at bare glassy carbon electrode (GCE), which limits the sensitive and selective detection of nitrite [13,14]. Thus, to develop new materials to promote the electron transfer and to lower the operating potential for nitrite oxidation is of considerable necessary. Recently, two-dimensional nanomaterial graphene nanosheets have been extensively used in many fields due to its unusual elec- tronic properties [15]. However, the hydrophobic property and the irreversible aggregation of graphene in aqueous solution poten- tially hampers its application in biological systems [16]. Graphene oxide (GO) is considered as a precursor of graphene, with various oxygen containing functional groups decorated on the basal planes (hydroxyl and epoxide groups) and edges (carbonyl and carboxyl) [17]. The unique structure of GO made it possess low toxicity and good hydrophilicity, and therefore can be applied in biological sys- tems. However, the poor electrical conductivity of GO limits its direct application as electrically active materials [18,19]. It was found that the presence of oxygen-containing functional groups on GO is beneficial to chemical modification or functionalization of it [20]. It can be functionalized by both covalent and noncovalent methods. The main advantage of covalent functionalization is to assure stable and well defined bonds between GO and the attached moieties. Thus, many efforts have been focused on the functional- ization of GO by covalent method to prepare the GO-based hybrid 0013-4686/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2013.11.060