Highly selective and sensitive photoelectrochemical detection of silver ions in complex industrial wastewater

Substandard discharge of industrial wastewater leads to abundant silver ions (Ag+) emission into water and soil, causing serious environmental threat. Precise and reliable detection of Ag+ is vital for environmental surveillance, while it remains a great challenge in complex actual environment. Herein, a lab-to-factory adoptable photoelectrochemical (PEC) approach for highly selective and sensitive detection of Ag+ in industrial wastewater has been first demonstrated. BiOI nanosheets (NSs) were prepared as photocathode and showed a spontaneous and selective ion-exchange process with Ag+ ions when it immersed into complicated industrial wastewater. The in situ generated AgI/Ag exhibits unique localized surface plasmonic resonance (LSPR) effect to modulate PEC signals for highly selective and sensitive Ag+ detection. As a result, the prepared photocathode delivers an ultralow detection limit (0.21 nM) and a broad linear range (up to 300 μM), outperforming most reported results. This work opens a feasible avenue for Ag+ monitoring in actual environment.