Photoelectrochemical assay based on CdS nanocrystal\hexagonal carbon-nitrogen tube nanocomposite for detection of silver ions

A photochemical assay was reported based on CdS nanocrystal (NC)\hexagonal carbon-nitrogen tube (HCNT) nanocomposite for the detection of Ag+. When CdS NCs were combined with HCNT, the photocurrent intensity was increased extensively. After incubation of Ag+ with CdS NC\HCNT nanocomposite-modified electrode, Ag2S was formed on the electrode by the ion-change reaction. As the band gap of Ag2S cannot match well with HCNT, the photogenerated electron-hole pairs cannot separate efficiently, so the photocurrent intensity decreases. A good linear relationship between the concentration of Ag+ in the range from 0.01 to 3 mu M and the corresponding photocurrent intensity was obtained with a detection limit of 3.3 nM (S/N = 3). The assay was employed to detect Ag+ in lake water and human serum with satisfactory results, which indicated that it might have a broad application in different areas.