One-step green synthesis of silver nanoparticle-modified reduced graphene oxide nanocomposite for H2O2 sensing applications

In the present study, silver nanoparticles-modified reduced graphene oxide nanocomposite (rGox/AgNPs) was obtained using a green synthesis method for reducing both Ag+ cations and graphene oxide sheets with tea extract. Tea polyphenols are highly reactive and water-soluble reducing agents allowing the correct reduction of precursors. Nanocomposite was conveniently analyzed using different techniques such as ultraviolet-visible and Fourier-transform infrared spectroscopies, X-ray diffraction, atomic force and transmission electron microscopies. Glassy carbon electrodes were conveniently modified with rGox/AgNPs nanocomposite and electrochemical tests were carried out to study the electrocatalytic properties of the GCE/rGox/AgNPs sensor against H2O2 reduction. The main analytical factors such as selectivity, sensitivity, time of response and stability, limit of quantification and detection were also studied. Our sensor had a sensitivity of about 236 μA mM−1cm−2 (R2 = 0.999) in the range of concentrations from 0.002 to 20 mM H2O2, a fast response (~2 s) and a limit of detection (S/N = 3) of about 0.73 μM. The selectivity of the sensor was tested against different biological interferences including dopamine, glutamate, glucose and ascorbic acid with promising results. In addition, sensor response was evaluated for 7 months without significant loss of sensitivity. Finally, the viability of using the GCE/rGox/AgNPs electrode for real samples was positively confirmed in different commercial disinfectant solutions and spiked samples (commercial milk and urine).