Facile preparation of metal-free graphitic-like carbon nitride/graphene oxide composite for simultaneous determination of uric acid and dopamine.

[Display omitted] • g-C 3 N 4 /GO was designed as a metal-free electrocatalyst for uric acid and dopamine. • g-C 3 N 4 /GO showed good electrocatalytic performance for the oxidation of uric acid and dopamine. • The sensor achieved the simultaneous determination of uric acid and dopamine at nanomolar level. • The sensor showed satisfactory reproducibility, selectivity and stability. Graphitic-like carbon nitride/graphene oxide composite nanosheets (g-C 3 N 4 /GO) were synthesized for simultaneous determination of uric acid (UA) and dopamine (DA). The surface features and electrochemical properties of the g-C 3 N 4 /GO were investigated by scanning electron microscopy, X-ray diffraction, cyclic voltammetry and electrochemical impedance spectra. The voltammetric responses of UA and DA were determinated by cyclic voltammetry and differential pulse voltammetry. g-C 3 N 4 /GO had significantly improved electrical conductivity, selective oxidation capacity and electrocatalytic activity. The proposed g-C 3 N 4 /GO modified glassy carbon electrode (GCE) consequently displayed excellent electrocatalytic activity for UA and DA, with a broad linear detection range (0.03–30 μM) and extremely low detection limits (UA 4.6 nM; DA 5.4 nM). The proposed g-C 3 N 4 /GO/GCE also demonstrated excellent reproducibility, selectivity and stability. The levels of UA and DA in human serum were measured by the g-C 3 N 4 /GO/GCE, and then the known concentrations of UA and DA were spiked to the samples, which proved that the recoveries were good. [ABSTRACT FROM AUTHOR]