Luo PYe MZhou WWan PMa ZQiu ZZhang JRU-SHI LIULian S.2022-04-252022-04-25202213858947https://www.scopus.com/inward/record.uri?eid=2-s2.0-85124323020&doi=10.1016%2fj.cej.2022.134951&partnerID=40&md5=b22e141bb1f8dcc5a7742b6d5b666575https://scholars.lib.ntu.edu.tw/handle/123456789/606921The traditional strategy to improve material stability is to cover the surface with a shell to resist adverse environmental factors. For the red-emitting fluoride materials with easily hydrolyzed Mn4+ on the surface, many strategies have been reported with limited effectiveness. In this work, simultaneous construction of an impermeable dual-shell on Mn4+-doped fluoride is proposed to solve the instability problem by a simple pyruvic acid (PA) treatment. The internal quantum efficiency of the K2SiF6:Mn4+ with dual-shell can be optimized up to 99.71%, the photoluminescence intensity can maintain 88.5% of the original intensity after soaking in water for 360 h, and the body color is not changed even in boiling. The reduction effect of the PA solution builds a hard fluoride shell by removal of the surface Mn4+, and the hydrogen bonding effect of PA molecular leads to the formation of a soft organic shell. The dual-shell can effectively block the damage of fluoride by external water molecules and achieve a significant improvement in water stability. The dual effect of PA is derived from its special molecular structure containing α-ketone carbonyl and carboxyl groups. This hypothesis is supported by the results of the moisture resistance of fluoride-treated with a variety of solvents similar in molecular structure to PA. In addition, DFT calculations simulated various hydrogen bond structures that may be formed between PA molecules and fluoride surface atoms. ? 2022 Elsevier B.V.Core-Shell-ShellFluorideMn4+Water StabilityWhite Light-Emitting DiodesFluorine compoundsHydrogen bondsKetonesManganese compoundsMoleculesStabilityCore shellCore-shell-shellEnvironmental factorsMaterials stabilityPyruvic acidRed-emittingWater stabilityWhite light emitting diodesShells (structures)[SDGs]SDG7journal article10.1016/j.cej.2022.1349512-s2.0-85124323020