Photoelectrochemical detection of Cu2+ based on ZnIn2S4/WO3 Z-scheme heterojunction

A one-step hydrothermal technique was utilized to generate WO3 nanosheets on fluorine-doped tin oxide (FTO) (WO3/FTO), which were subsequently modified with ZnIn2S4 microspheres to create a Z-scheme heterojunction ZnIn2S4/WO3/FTO electrode for Cu2+ detection. The heterojunction exhibited excellent photoelectric conversion efficiency, which was nearly 2.5-fold and 5.1-fold greater than that of WO3 and ZnIn2S4. The reduced photoelectrochemical response signal was caused by the formation of CuxS and enabled Cu2+ assessment in water samples. After optimizing the experimental conditions, the anodic photocurrent at 0 V vs SCE in 0.100 M phosphate buffer (pH 7.0) containing 0.100 M L-ascorbic acid was linear with the common logarithm of Cu2+ concentration from 5.00 nM to 100 mu M, with a limit of detection of 1.2 nM (S/N = 3). Satisfactory recovery results were obtained in the analyses of Xiangjiang River water samples.