A generalized in situ electrodeposition of Zn doped CdS-based photoelectrochemical strategy for the detection of two metal ions on the same sensing platform

An efficient strategy for the sensitive detection of Cd2+ and Cu2+ on the same sensing platform was first developed based on the photocurrents generated from the electrodeposited Zn doped CdS (CdZnS) film. The enhancement of the photocurrents, which was directly obtained from the in situ electrodeposited CdZnS on ITO with the gradual addition of Cd2+, was used an indicator for the content of Cd2+ with theoretical and technical simplicity. Moreover, the electrodeposited CdZnS was further applied to sensing of Cu2+ based on the interaction between Cu2+ and S2− by immersing the hetero-structural film electrode into a Cu2+-containing sample for an appropriate time, leading to decrease the photocurrent of CdZnS. The decrease extent of photocurrent was depended on the concentration of Cu2+ in the sample solution. Due to the sensitivity of the photoelectrochemical (PEC) sensor was enhanced obviously through the doping of Zn, the present electrodeposited PEC method demonstrated acceptable linear range of 10−9–10−2M and 10−8–10−4M, with low detection limit down to 0.35nM and 3nM for Cd2+ and Cu2+ respectively, which were lower than the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The proposed CdZnS-based PEC strategy achieved two metal ions detection on the same sensing platform, which had positive and significant effect on solving the common problems, such as time-consuming, high cost, complex operation and high detection limit in the detection of metal ions. In addition, the proposed PEC device was further successfully applied to an assay of Cd2+ and Cu2+ in water sample. •An efficient protocol for the detection of Cd2+ and Cu2+ was developed.•The detection of Cd2+ and Cu2+ on one sensing platform was first proposed.•The detection of two metals was based on the electrodeposited Zn doped CdS film.•The doping of Zn can improve the sensitivity of the PEC sensor obviously.