Preparation and application of graphene-poly (diallyldimethylammoniumchloride)-iron oxide nanoparticles buckypaper for hydrogen peroxide detection

We have reported the preparation and characterization of a novel, freestanding, paper-like graphene (G)-poly(diallyldimethylammoniumchloride) (PDDA)-Fe₃O₄ nanoparticles (NPs) composite. This G-based flexible buckypaper (BP) composed of stacked G-PDDA-NP platelets exhibited excellent mechanical properties, superior electrical properties, and enzyme mimetic activity, making it potentially suitable for in electrochemical sensor applications. The negatively charged NPs were immobilized on positively charged G-PDDA through the electrostatic interaction to form nanoscale G-PDDA-NP platelets, which were further assembled by flow-directed assembly to form BP. The resulting BP has macroscopic flexibility and stiffness due to the van der Waals forces between nanoscale G-PDDA-NP platelets and interlocking-tile arrangement of the platelets. The morphology and structure of the individual G-PDDA-NP platelets and the resulting BP were analyzed by using AFM, SEM and EDX. The BP was attached to an Au or Pt electrode to construct a nonenzyme H₂O₂ chemical sensor. The NPs acted as a "spacer" to increase the distance between the G sheets and decrease the chances of formation of a stacked graphitic structure, thereby increasing the surface area of the G electrode. The Fe₃O₄ NPs immobilized and embedded in the BP have intrinsic enzyme mimetic activity like natural peroxidase. The high surface area and excellent electrical conductivity of G improved the catalytic properties of NPs. The obtained H₂O ₂ chemical sensor exhibited prominent electrocatalytic activity towards H₂O₂, with a wide linear range from 10 ppm (∼0.3 μM) to 800 ppm (∼23 mM), correlation coefficient of 0.986, and a high sensitivity of 218 μA mM^-1 ·cm^-2. Such low-cost G-PDDA-NP composite BPs prepared by facile methods pave way towards novel sensors with better performance.