Dual-Modal Photoelectrochemical and Visualized Detection of Copper Ions.

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.