Dual-Modal Photoelectrochemical and Visualized Detection of Copper Ions

[Image: see text] Copper is one of the extensively utilized heavy metals in modern industry and can be easily released into the environment due to high solubility of copper ions (Cu(2+)). Its percolation in water and accumulation along the food chain pose a serious threat to human health. Hence, it is of great significance to explore a novel, facile, and sensitive detection method for Cu(2+). Based on the intriguing photo-to-electricity conversion process of CdS QDs, as well as desirable electrochromic property of WO(3) NFs, a dual-modal photoelectrochemical (PEC) and visualized detection platform for Cu(2+) is fabricated. The electrochromic WO(3) NFs act as a display for the Cu(2+) concentration, of which the color change could be observed directly by the naked eye, while the PEC signal provides accurate data for further analysis. In this work, a sensitive detection of Cu(2+) in the range of 1 × 10(–5) to 5 × 10(–4) M is achieved, with a detection limit of 3.2 × 10(–6) M. The dual-modal analysis gives more choices for signal readouts with enhanced quantification reliability, which is adaptive for diverse application scenarios, especially for on-site investigation. This protocol offers a prototype for quick and reliable detection of the Cu(2+) concentrations, and is promising for other environmental pollutants.