Abstract: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.
