Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺/silica core–shell particles synthesized via urea combustion method for carbon dioxide reduction in plants

Strontium Aluminate doped with Europium and Dysprosium is one of the most widely studied phosphors because of its high intensity and long persistence time. In this study, the unique characteristics of strontium aluminate based phosphors, specifically Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺, was utilized as light source for plants for enhanced carbon dioxide reduction in dark field conditions. The Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ phosphor was synthesized using the combustion method. Stoichiometric amounts of aqueous precursors were dissolved in water, then placed in a high temperature furnace at 600 °C to obtain a foamy, amorphous precursor powder. The powders were cooled to room temperature and then grinded. After grinding, the powders were calcined for 8 h at 1300 °C. The powders were then encapsulated with silica particles using the Stöber process to prevent the oxidation of Eu²⁺ without a reducing atmosphere during calcination. The obtained coated and uncoated particles were then characterized using SEM, TEM–EDX, XRD and photoluminescence analysis to determine the effect of the core–shell structure on the luminescence properties of the phosphors. Finally, the obtained phosphor-silica core–shell particles will be attached to the surface of four different plant species commonly grown indoors using a mixture of natural oils and waxes as adhesive. The effect of the addition of phosphor as an external light source on the amount of carbon dioxide production of the plants will be monitored and compared to a control specimen without the phosphor as well as with other artificial light sources.