Photoluminescence/optical-absorption modulation of layered lanthanide molybdates for chemical sensing of reductive materials

Abstract This work has found K1−δHδEu(MoO4)2 as a novel material for detecting reducing agents. The red emission from Eu3+ was notably diminished in the presence of the reducing agent, followed by its restoration in the presence of the oxidizing agent, demonstrating a significant luminescence modulation. This effect is believed to be induced by polaron absorption between Mo5+ and Mo6+, deactivating the red luminescence of Eu3+. Notably, the facile proton deinsertion stemming from the layered structure contributed to its exceptional restoration capability.