Facile synthesis of Ag@Cu2O heterogeneous nanocrystals decorated N-doped reduced graphene oxide with enhanced electrocatalytic activity for ultrasensitive detection of H2O2

A nanohybrid composed of Ag@Cu2O heterogeneous nanocrystals supported on N-doped reduced graphene oxide (Ag@Cu2O/N-RGO) has been synthesized by a simple wet-chemical method. The resultant composite consists of N-RGO sheets fully and homogeneously coated with a dense layer of Ag@Cu2O nanocrystals. Both Ag and N-RGO are in direct contact with Cu2O, and Ag nanoparticles with sizes of 2–5 nm are mainly deposited on the surface of Cu2O cubes (edge length of 500 nm). The electrochemical studies reveal that the ternary Ag@Cu2O/N-RGO composite exhibit significantly enhanced electrocatalytic activity for H2O2 sensing compared with either the single component (N-RGO) or two component systems (Cu2O/N-RGO and Ag/N-RGO), which is mainly due to the synergetic catalysis of the ternary system. The nonenzymatic sensor based on Ag@Cu2O/N-RGO composite shows overwhelmingly superior comprehensive performance for the H2O2 detection over the documented Ag-based sensors. More specifically, it displays a rapid response (10 s) to H2O2 over a wide linear range of 54–700 nM with a high sensitivity of 1298.3 μA mM−1 cm−2 and a low detection limit of 10 nM. Moreover, the sensor also exhibits the preferable selectivity in the presence of biologically coactive compounds accompanied with long-term stability and good reproducibility.