Photoelectrochemical determination of Cu2+ ions based on assembly of Au/ZnS nanoparticles

A sensitive photoelectrochemical method for detection of Cu2+ ions was achieved by the Au/ZnS nanoparticles modified electrode. The Au nanoparticles were first self-assembled on indium tin oxide (ITO) film coated glass using poly dimethyl diallyl ammonium chloride (PDDA) molecules as linkers, and then ZnS nanoparticles were immobilized on the gold surface by the same method. In the presence of light and electron donor of triethanolamine (TEA), the prepared electrode generated a stable anode photocurrent. As Cu2+ ions were present in the solution, the interaction between Cu2+ ions and ZnS nanoparticles occurred. The formation of CuxS (x = 1, 2) prevented the electron from transferring to the ITO electrode and decreased the photocurrent. The photocurrent decrement depended on the concentration of Cu2+ ions. The sensor shows a linear range of 1 nM-1 μM for measurement of Cu2+ ions, with a detection limit of 0.5 nM. The method was applied to the detection of Cu2+ ions in real samples with a satisfactory result.