Cuprous oxide microspheres on graphene nanosheets: an enhanced material for non-enzymatic electrochemical detection of H2O2 and glucose

Abstract

We report here a facile one-step green synthesis of cuprous oxide microspheres (Cu₂OMS) on reduced graphene oxide (RGO) by reducing Cu²⁺ ions and GO with sodium ascorbate synchronously in the presence of sodium hydroxide. Cu₂OMS with different sizes on the surface of RGO were successfully synthesized by adjusting the mass ratio of GO to CuSO₄·5H₂O in this reaction system. It was found that uniform Cu₂OMS were formed on RGO by increasing the mass ratio from 1 : 20 to 1 : 80. The synthesized Cu₂OMS–RGO composites with different structures were immobilized onto glassy carbon electrodes and applied to construct electrochemical hydrogen peroxide (H₂O₂) and glucose sensors. The results indicate that the Cu₂OMS–RGO composite created with the mass ratio of 1 : 80 presents the best sensor performances. The fabricated H₂O₂ sensor exhibits a fast amperometric response to H₂O₂ with a linear detection range from 0.005 to 2.775 mM and a detection limit of 0.0108 mM, and the glucose sensor has a linear detection range from 0.001 to 0.419 mM and a detection limit of 7.288 × 10⁻⁴ mM. The superior performance is ascribed to the unique structure of the synthesized Cu₂OMS and the excellent conductivity of the RGO content. In addition, the synthesized Cu₂OMS–RGO composites exhibited improved electrochemical stability. Such novel Cu₂OMS–RGO hybrid materials represent promising non-enzymatic electrochemical glucose and H₂O₂ sensors with high sensitivity and selectivity, improved stability, and fast amperometric response.