本文采用乙二醇还原法、抗坏血酸还原法、柠檬酸三钠还原法及硼氢化钠还原法合成胶体金溶液，并将其负载于XC-72上制备Au/XC-72催化剂。X射线衍射（XRD）表明四种方法制备的催化剂均具有明显的Au特征衍射峰，且硼氢化钠还原法制备的Au衍射峰最平缓。透射电子显微镜（TEM）表明硼氢化钠还原法制备的金纳米颗粒（Au NPs）粒径最小，在XC-72表面分布均匀，其他三种方法制备的Au NPs粒径较大，且发生不同程度的团聚。利用制备的催化剂（Au/XC-72）修饰玻碳电极（GCE）并用于L-半胱氨酸（L-CySH）的电催化氧化机制研究，结果显示硼氢化钠还原法制备的Au/XC-72在pH为2时对L-CySH的催化氧化较其它三种方法制备的材料表现出最优的活性，且在1 mM~10 mM的范围内呈现线性关系，表明L-CySH在Au/XC-72上的氧化反应的速率是受扩散过程控制的。电催化活性高粒径小的Au/XC-72修饰GCE构建的传感器具有广泛的实际应用价值。

A colloidal gold solution was prepared by the methods of ethylene glycol reduction, ascorbic acid reduction, trisodium citrate reduction, and sodium borohydride reduction and supported on XC-72 substrate. Results of X-ray diffraction (XRD) showed that the catalyst prepared by the four methods contained obvious characteristic peak of Au. The Au/XC-72 diffraction peak prepared by sodium borohydride reduction method was the most gradual. Results of transmission electron microscopy (TEM) indicated that the Au NPs prepared by the sodium borohydride reduction method achieved a particle size of less than 5 nm and revealed a uniform distribution on the surface of XC-72. The Au NPs prepared by the other three methods presented larger particle size agglomeration. These catalysts (Au/XC-72) were modified on glassy carbon electrode (GCE) and used for electrochemical oxidation of L-cysteine (L-CySH). The results showed that the preparation of Au/XC-72 modified GCE by sodium borohydride reduction exihibited the best electrocatalytic activity of L-CySH in pH 2 PBS. The L-CySH oxidation was a diffusion-controlled process. It showed a good linear relationship ranging from 1 mM to 10 mM. The sensor constructed by Au/XC-72 modified GCE with high electrocatalytic activity and small particle size has great potential in practical applications.

国家自然科学基金面上项目（31671870）；广东省公益研究与能力建设专项资金项目（2016B020203001）；广州市科技计划项目对外科技合作计划（201807010102）；广州市珠江科技新星专项（201610010105）