A novel hierarchical 3D N-Co-CNT@NG nanocomposite electrode for non-enzymatic glucose and hydrogen peroxide sensing applications

A novel 3D nanocomposite of nitrogen doped Co-CNTs over graphene sheets (3D N-Co-CNT@NG) have been successfully fabricated via a simple, scalable and one-step thermal decomposition method. This 3D hierarchical nanostructure provides an admirable conductive network for effective charge transfer and avoids the agglomeration of NG matrices, which examine direct as well as non-enzymatic responses to glucose oxidation and H₂O₂ reduction at a low potential. The novel electrode showed excellent electrochemical performance towards glucose oxidation, with high sensitivity of 9.05 μA cm⁻² mM⁻¹, a wide linear range from 0.025 to 10.83 mM, and a detection limit of 100 nM with a fast response time of less than 3 s. Furthermore, non-enzymatic H₂O₂ sensors based on the 3D N-Co-CNT@NG electrode exhibited high sensitivity (28.66 μA mM⁻¹ cm⁻²), wide linear range (2.0–7449 μM), low detection limit of 2.0 μM (S/N=3), excellent selectivity, decent reproducibility and long term stability. Such outstanding electrochemical performance can be endorsed to the large electroactive surface area, unique porous architecture, highly conductive networks, and synergistic interaction between N-Co-CNTs and nitrogen doped graphene (NG) in the novel 3D nanocomposite. This facile, cost-effective, sensitive, and selective glucose as well as H₂O₂ sensors are also proven to be appropriate for the detection of glucose as well as H₂O₂ in human serum.