▎ 摘　　要

In this study, branched polyethyleneimine (PEI) was covalently linked to carboxylic acid functionalized graphene (GO-COOH) to form GO-COOH/PEI composites. Transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectra and thermogravimetric analysis were used to characterize the obtained composites. Electrochemical measurements indicated that the modification of the composites on the electrode could efficiently enhance the voltammetric response, suggesting the potential application for making electrochemical sensors. Moreover, our results also indicated that the electrocatalytic oxidation of ammonia could be observed on the GO-COOH/PEI composites modified glassy carbon electrode. Consequently, our observations demonstrated that GO-COOH/PEI composites were excellent materials for electrochemical sensing.