▎ 摘　　要

NOVELTY - Preparing a nitrogen-doped graphene composite comprises adding potassium permanganate and manganese sulfate monohydrate in deionized water under stirring, transferring to a high-pressure reactor for reaction, and washing and drying the product to obtain manganese dioxide precursor. The selenium powder and sodium borohydride are added to the sodium hydroxide solution under stirring, added distilled water under stirring, subjected manganese dioxide precursor product to a water bath reaction, and then washed and dried to obtain nano-selenium/manganese dioxide. The nano-selenium/manganese dioxide is added into an organic solvent for dispersion to obtain nano-selenium/manganese dioxide dispersion liquid. The nitrogen-doped graphene is added into an organic solvent for dispersion to obtain nitrogen-doped graphene dispersion. USE - Method for preparing a nitrogen-doped graphene composite material loaded with nano-selenium/manganese dioxide used for detecting content of carbendazim in vegetables, fruits, or soil (claimed). ADVANTAGE - The nitrogen-doped graphene composite material has wide linear range, low detection limit, strong anti-interference performance and good detection stability. DETAILED DESCRIPTION - Preparing a nitrogen-doped graphene composite comprises adding potassium permanganate and manganese sulfate monohydrate in deionized water under stirring, transferring to a high-pressure reactor for reaction, and washing and drying the product to obtain manganese dioxide precursor. The selenium powder and sodium borohydride are added to the sodium hydroxide solution under stirring, added distilled water under stirring, subjected manganese dioxide precursor product to a water bath reaction, and then washed and dried to obtain nano-selenium/manganese dioxide. The nano-selenium/manganese dioxide is added into an organic solvent for dispersion to obtain nano-selenium/manganese dioxide dispersion liquid. The nitrogen-doped graphene is added into an organic solvent for dispersion to obtain nitrogen-doped graphene dispersion. The nano-selenium/manganese dioxide dispersion liquid is mixed with the nitrogen-doped graphene dispersion liquid, and then ultrasonicated to get the nitrogen-doped graphene composite material loaded with nano-selenium/manganese dioxide. An INDEPENDENT CLAIM is included for a method for using nitrogen-doped graphene composite material loaded with nano-selenium/manganese dioxide, which involves using a three-electrode system formed by using nitrogen-doped graphene composite material loaded with nano-selenium/manganese dioxide as the working electrode, the platinum electrode as the counter electrode, and the saturated calomel electrode as the reference electrode, connecting the three-electrode system to the electrochemical workstation, measuring oxidation peak current value of carbendazim in the sample solution to be tested by differential pulse voltammetry, converting the concentration of carbendazim was converted according to the standard addition method, and obtaining the content of carbendazim in the actual sample.