关键词: 二氧化钛纳米颗粒, 还原氧化石墨烯, 对硝基苯酚, 差分脉冲伏安法

Abstract:

 4-nitrophenol (4-NP) has become factitious pollution, and presented a serious threat to the nature and human health. It is necessary to develop a convenient and fast detection method. In this work, the glassy carbon electrode modified by titanium dioxide nanoparticles (TiO₂NPs)/reduced graphene oxide (RGO) composite as an electrochemical sensor was studied for the trace detection of 4-NP. The morphology of the composite was characterized by scanning electron microscopy (SEM). The homogeneous mixing of titanium dioxide nanoparticles and reduced graphene oxide increased the specific surface area of the composite, and facilitated the electrochemical reaction of 4-NP. The electrochemical characteristics of the composite electrode were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the solution of 5 mmol·L^-1 [Fe(CN)₆]^3-/4-, showing excellent electrochemical performance. In 0.067 mol·L^-1 phosphate buffer solution with a pH of 6.0, differential pulse voltammetry was used to detect trace amounts of 4-NP. This method was satisfactory for the determination of 4-NP due mainly to the higher catalytic activity of TiO2NPs/RGO complexes for 4-NP. The current peak value and concentration of 4-NP showed a good linear relationship. The detection range was 10  μmol·L^-1 ~ 350  μmol·L^-1 and the detection limit was 0.13  μmol·L^-1. Interferences of other pollution compounds, such as 2-nitrophenol, did not impact the sensing to 4-NP. In addition, the electrochemical sensor exhibited excellent repeatability and stability (The TiO₂NPs/RGO/GCE electrodes retained 90.2% of the initial response current after two weeks). Compared with some other electrochemical sensors reported, this sensor had the advantages of a large detection range, low detection limit, stable operation, repeatable test, low cost, simple and rapid analysis, and based on these characteristics, the TiO₂NPs/RGO/GCE electrochemical sensor can provide an efficient detection for 4-NP.

Key words: TiO₂NPs, RGO, 4-nitrophenol, differential pulse voltammetry