Electroanalysis of an Iron@Graphene‐Carbon Nanotube Hybrid Material

Abstract

Abstract Hybrid nanomaterials have outstanding properties that are superior to the corresponding constituents working alone. This work reports on the electroanalysis of a hybrid material‐decorated screen‐printed carbon electrode (SPCE) that consists of iron nanoparticles supported at multi‐wall carbon nanotubes (MWCNT), coated with graphene layers, named Fe@G‐MWCNT. Electrochemical and morphological characterizations were carried out by cyclic voltammetry, electrochemical impedance spectroscopy and high‐resolution transmission electron microscopy, respectively. After optimizing the amount of hybrid material to be drop casted at the SPCE, its electrochemical activation in sulphuric acid produced an enhanced response. The resultant electrochemically reduced Fe@G‐MWCNT‐e‐modified electrode exhibited a diffusion‐controlled redox process with an enhanced heterogeneous electron‐transfer rate constant of 3.21×10 −2 cm⋅s −1 , which was superior to that from the MWCNT counterpart. However, it was slightly lower than that from a Fe‐MWCNT‐decorated electrode. The graphene coating limited slightly the electron‐transfer process, but works as a protective layer that prevent the loss of Fe catalytic activity. The electrochemical response of the hybrid with graphene coated Fe decreased only a 24.3 % after one week, respect to 51.9 % of the uncoated one. In addition, the hybrid material‐modified electrode exhibited electrocatalytic activity towards the reduction of H 2 O 2 in a linear range of 0.5 mM to 9.8 mM, with sensitivity of 7.97 μA⋅mM −1 and LOD of 0.65 mM, thereby opening an avenue for the development of more specific and highly sensitive Fe@G‐MWCNT hybrid‐based (bio) sensors.