Graphene nanosheets functionalized with Nile blue as a stable support for the oxidation of glucose and reduction of oxygen based on redox replacement of Pd-nanoparticles via nickel oxide

•New nanocomposite is introduced based on NiO-Nile blue nanoparticles decorated on reduce graphene oxide.•A bimetallic system was synthesized by replacement between NiO and Pd nanoparticles.•The nanocomposites structure were characterized by spectroscopic and electrochemical methods.•The modified decorated graphene oxide was used for the oxidation of glucose and reduction of oxygen.

A novel, cheap and simple enzymeless glucose sensor is introduced based on Pd/NiO nanoparticles decorated on Nile blue functionalized reduced graphene oxide (rGO). First, NiO was decorated on rGO and/or Nile blue functionalized rGO. Then, they were converted to bimetallic system by replacement of NiO with Pd nanoparticles, (Pd/NiO@rGO and Pd/NiO@Nile–rGO) to prepare the modified carbon paste electrodes (CPE). Pd/NiO@Nile–rGO was prepared using functionalized graphene oxide with Nile blue through diazonium reaction and deposition of Pd–NiO nanoparticles with chemical reaction. The nanocomposites structure were characterized by spectroscopic and electrochemical methods. Electrochemical studies showed that Pd/NiO@Nile–rGO has higher electrocatalytic activities toward glucose oxidation compare to Pd/NiO@rGO nanoparticles. Potential cycling test was employed to confirm the high sensitivity and stability of Pd/NiO@Nile–rGO compare to Pd/NiO@rGO. Then, a sensitive amperometric detection of glucose is achieved at –0.040 V (vs. Ag/AgCl) with a low detection limit of 2.2 μmol L–1 and with a wide linear range of 0.020–20.0 mmol L–1 glucose using Pd/NiO@Nile–rGO/GCE. Five different Pd/NiO@Nile–rGO/CPEs were tested separately for the amperometric response of glucose, providing a relative standard deviation of 4.8%.The selectivity of the modified electrode was studied too. The applicability of Pd/NiO@Nile–rGO/CPE was investigated by determining glucose in blood serum samples with satisfactory results. In the second part of this work the electrocatalytic activity of the modified electrodes for the electro-reduction of oxygen have been studied too. The results of our studied confirmed that Pd/NiO@Nile–rGO nanocomposites act as an electrocatalyst for the oxidation of glucose and reduction of oxygen, beside them. Thus, the nanocomposite is a good candidate for glucose fuel cell.

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