3D Network and 2D Paper of Reduced Graphene Oxide/Cu₂O Composite for Electrochemical Sensing of Hydrogen Peroxide

In this study, two-dimensional (2D) and three-dimensional (3D) freestanding reduced graphene oxide-supported Cu₂O composites (Cu₂O-rGO) were synthesized via simple and cost-efficient hydrothermal and filtration strategies. The structural characterizations clearly showed that highly porous 3D graphene aerogel-supported Cu₂O microcrystals (3D Cu₂O-GA) have been successfully synthesized, and the Cu₂O microcrystals are uniformly assembled in the 3D GA. Meanwhile, paper-like 2D reduced graphene oxide-supported Cu₂O nanocrystals (2D Cu₂O-rGO-P) have also been prepared by a filtration process. It was found that the products prepared from different precursors and methods exhibited different sensing performances for H₂O₂ detection. The electrochemical measurements demonstrated that the 3D Cu₂O-GA has high electrocatalytic activity for the H₂O₂ reduction and excellent sensing performance for the electrochemical detection of H₂O₂ with a detection limit of 0.37 μM and a linear detection range from 1.0 μM to 1.47 mM. Meanwhile, the 2D Cu₂O-rGO-P structure also showed good electrochemical sensing performance toward H₂O₂ detection with a much wider linear response over the concentration range from 5.0 μM to 10.56 mM. Compared to the previously reported sensing materials, the as-obtained 2D and 3D Cu₂O-rGO materials exhibited higher electrochemical sensing properties toward the detection of H₂O₂ with high sensitivity and selectivity. The 2D and 3D Cu₂O-rGO composites also exhibited high sensing performance for the real-time detection of H₂O₂ in human serum. The present study indicates that 2D and 3D graphene-Cu₂O composites have promising applications in the fabrication of nonenzymatic electrochemical sensing devices.