Enhanced electron transfer mediated detection of hydrogen peroxide using a silver nanoparticle-reduced graphene...

The current study aims at the development of an electrochemical sensor based on a silver nanoparticle-reduced graphene oxide-polyaniline (AgNPs-rGO-PANI) nanocomposite for the sensitive and selective detection of hydrogen peroxide (H₂O₂). The nanocomposite was fabricated by simple in situ synthesis of PANI at the surface of rGO sheet which was followed by stirring with AEC biosynthesized AgNPs to form a nanocomposite. The AgNPs, GO, rGO, PANI, rGO-PANI, and AgNPs-rGO-PANI nanocomposite and their interaction were studied by UV-vis, FTIR, XRD, SEM, EDX and XPS analysis. AgNPs-rGO-PANI nanocomposite was loaded (0.5 mg cm^-2) on a glassy carbon electrode (GCE) where the active surface area was maintained at 0.2 cm² for investigation of the electrochemical properties. It was found that AgNPs-rGO-PANI-GCE had high sensitivity towards the reduction of H₂O₂ than AgNPs-rGO which occurred at -0.4 V vs. SCE due to the presence of PANI (AgNPs have direct electronic interaction with N atom of the PANI backbone) which enhanced the rate of transfer of electron during the electrochemical reduction of H₂O₂. The calibration plots of H₂O₂ electrochemical detection was established in the range of 0.01 μM to 1000 μM (R ² = 0.99) with a detection limit of 50 nM, the response time of about 5 s at a signal-to-noise ratio (S/N = 3). The sensitivity was calculated as 14.7 μA mM^-1 cm^-2 which indicated a significant potential as a non-enzymatic H₂O₂ sensor.