Self-assembly synthesis of a hierarchical structure using hollow nitrogen-doped carbon spheres as spacers to separate the reduced graphene oxide for simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid

Abstract

A self-assembly approach was used to prepare a hierarchical structure (HNCS-RGO) using hollow nitrogen-doped carbon spheres (HNCSs) as spacers to separate the reduced graphene oxide nanosheets (RGO). Then, it was applied to simultaneous electrochemical determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) for the first time. Compared with the bare glassy carbon (GC) and the RGO modified GC (RGO/GC) electrodes, the HNCS-RGO modified GC (HNCS-RGO/GC) electrode shows higher electrocatalytic activity towards oxidation of AA, DA and UA. Especially, the peak potential separation between AA and DA at the HNCS-RGO/GC electrode is up to 252 mV, which is much larger than that at the RGO/GC electrode (205 mV). In the co-existence system of AA, DA and UA, the linear response ranges of the HNCS-RGO/GC electrode for AA, DA and UA are 50–1200 μM, 0.5–90 μM and 1–70 μM, respectively, and the detection limits (S/N = 3) are 650 nM, 12 nM and 18 nM, respectively. Also, the HNCS-RGO/GC electrode has good reproducibility and high stability. In addition, the HNCS-RGO/GC electrode was used successfully for simultaneous determination of AA, DA and UA in human urine samples. These results demonstrate that the HNCS-RGO hierarchical material is a promising candidate as an advanced electrode material in electrochemical sensing and electrocatalytic applications.