Tunable-Emissive Zeolite-Confined Silver Nanoclusters as a Rapid and Highly Sensitive Photoluminescent Sensor for Trace Water Detection in Organic Solvents

Zeolite-confined silver nanoclusters (AgNCs/Zeolite) are highly promising luminescent materials. Nevertheless, the controlled synthesis of AgNCs/Zeolite composites with tunable luminescent responses remains a persistent challenge. In this study, highly luminescent AgNCs/Zeolite composites are developed through the counter-cations engineering strategy via confining AgNCs within the cages of FAUX with Na⁺ and Zn²⁺ as the counter cations (Ag-FAUX(Na/Zn)), which show water-triggered switchable yellow/green tunable-emissive properties with PLQY up to 90% and high tolerance to chemical reduction. Specifically, dehydration of Ag-FAUX(Na/Zn) increases its PLQY from 60% to 90% and shifts the emission peak from 560 to 520 nm, whereas the yellow emission of the sample without Zn²⁺ (Ag-FAUX(Na/Zn)) is almost completely quenched upon dehydration. The remarkably enhanced luminescence upon dehydration can be tentatively ascribed to the coordination of Zn²⁺ with framework oxygen (O_F) of FAUX, thereby preventing AgNCs from direct interaction with O_F of Ag-FAUX(Na/Zn), and finally forming the stable, tightly confined Ag₄ interacting with nonframework oxygen and zinc atoms simultaneously. The Ag-FAUX(Na/Zn) composites demonstrated exceptional performance in fluorescence detection of trace water in organic solvents, achieving high sensitivity, a low detection limit of 0.015% v/v, rapid response times of less than 0.5 s, and reusability, thereby positioning it as a promising candidate for advanced fluorescence detection applications.