Photoelectrochemical detection of Cu based on ZnInS/WO Z-scheme heterojunction.

A one-step hydrothermal technique was utilized to generate WO nanosheets on fluorine-doped tin oxide (FTO) (WO/FTO), which were subsequently modified with ZnInS microspheres to create a Z-scheme heterojunction ZnInS/WO/FTO electrode for Cu detection. The heterojunction exhibited excellent photoelectric conversion efficiency, which was nearly 2.5-fold and 5.1-fold greater than that of WO and ZnInS. The reduced photoelectrochemical response signal was caused by the formation of CuS and enabled Cu 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 Cu concentration from 5.00 nM to 100 μM, 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.