Fabrication of hierarchical 3D prickly ball-like Co–La oxides/reduced graphene oxide composite for electrochemical sensing of l-cysteine

A novel 3D prickly ball-like Co–La oxides/reduced graphene oxide composite (Co–La oxides/rGO) has been successfully synthesized by a facile thermal evaporation method. Co–La oxides were hierarchical spiny globular structure made up of numerous radially-grown nanowires with the size of about 50 nm in width. Some of the nanowires grow vertically on the surface of rGO nanosheets. GO was thermally reduced to rGO. XPS data showed that the Co3+, Co2+ and La3+ existed in the prepared samples. The possible growth mechanism was tentatively proposed. The application of the 3D prickly ball-like Co–La oxides/rGO as electrode-modified material for electrochemical oxidation of l-cysteine was studied. The prepared prickly ball-like Co–La oxides/rGO modified electrode expressed prominent electrocatalytic ability for the electrochemical oxidation of l-cysteine. Under optimum experimental conditions, the current response of l-cysteine were linear with its concentration in the range of 1.0–888.0 μM with a low detection limit of 0.1 μM (S/N = 3). The sensor was used to evaluate its application for the detection of l-cysteine in the real samples.