Hydration-Regulated Tunable Trichromatic Luminescence of Mg2+ Co-Doped Ag-LTA Zeolite for Humidity Detection

Silver nanoclusters (AgNCs) with exceptional luminescence suffer from an aggregation-induced loss of their unique quantum confinement effects. LTA zeolites are ideal hosts for stabilizing AgNCs, yet most reported water-responsive AgNC@LTA systems only exhibit binary luminescence switching, restricting high-resolution multilevel environmental monitoring. Herein, we construct a Mg2+-regulated AgNC@LTA system via sequential ion exchange and thermal treatment. The as-prepared Ag-LTA(Na/Mg) achieves continuous three-state luminescence switching with yellow emission in dehydration, red in slight hydration, and green in full hydration. Mechanistic studies reveal that Mg2+ isolates AgNCs, blocks framework-to-cluster charge transfer, and stabilizes the intermediate excited state. The luminescence was confirmed as phosphorescence. This material realizes a naked-eye-resolvable color transition over 0%-60% relative humidity with excellent reversibility, breaking the binary limitation and offering an avenue for high-precision visual humidity sensors.