Background: Graphene quantum dots (GQD) is a new member of carbon nanomaterial that has attracted increasing attention owing to its better chemical inertness, low cytotoxicity, large specific surface area, cheap cost, suitable conductivity and excellent biocompatibility.

Methods: Electrochemical behaviors of this modified electrode were studied by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical investigations of Nafion/Hb/GQD/ CILE were carried out with electrochemical parameters calculated.

Results: In the phosphate buffer solution with a pH value of 5.0, good linear relationships between the catalytic reduction current and the concentration of substrate were got for TCA (6.0~100.0 mmol·L-1), NaNO2 (2.0~12.0 mmol·L-1) and H2O2 (6.0~30.0 mmol·L-1). The proposed method was applied to NaNO2 concentration detection in soak water from picked vegetables with satisfactory results.

Conclusion: This Nafion/Hb/GQD/CILE had a good bioelectrocatalytic activity to different substrates such as trichloroacetic acid, NaNO2 and H2O2 reduction with the advantages including wide detection range, low detection limit and good stability. Therefore, the application of GQD in electrochemical sensor was extended in this paper.

背景：石墨烯量子点（GQD）是碳纳米材料的新成员，由于其化学惰性好，细胞毒性低，比表面积大，成本低廉，合适的电导率和出色的生物相容性而受到越来越多的关注。

方法：通过循环伏安法和电化学阻抗谱研究了该修饰电极的电化学行为。用计算的电化学参数进行Nafion / Hb / GQD / CILE的电化学研究。

结果：在pH值为5.0的磷酸盐缓冲溶液中，TCA（6.0〜100.0mmol·L-1），NaNO2（2.0〜12.0mmol·L）的催化还原电流与底物浓度之间具有良好的线性关系。 -1）和H2O2（6.0〜30.0mmol·L-1）。将该方法用于挑菜浸泡水中NaNO2浓度检测，结果令人满意。

结论：该Nafion / Hb / GQD / CILE对三氯乙酸，NaNO2和H2O2等不同底物具有良好的生物电催化活性，具有检测范围广，检测限低，稳定性好等优点。因此，本文扩展了GQD在电化学传感器中的应用。