Calcination-controlled fabrication of carbon dots@zeolite composites with multicolor fluorescence and phosphorescence

In light of the exceptional optical qualities, luminous carbon dots (CDs), particularly those with room-temperature phosphorescence (RTP), have a wide range of applications in a variety of fields. However, modulating afterglow emissions practically and efficiently remains a serious difficulty. Herein, a feasible strategy of calcination combined with in-situ synthesis is proposed to fabricate CDs-based composites with multicolor fluorescence (FL) and phosphorescence. Through pre-selection of small pore RHO zeolite as a matrix, CDs have been successfully embedded due to strong guest–host interaction achieved by in-situ hydrothermal synthesis. By the unique pore architecture and excellent stability of the zeolite matrix, the surface oxidation degree and the carbon core size of confined CDs are engineered by temperature-controlled calcination. The resulting composites exhibit tunable FL (from 416 to 566 nm) and RTP (from 440 to 585 nm) in solid and aqueous solution, in which rarely occurring deep blue RTP is observed with a lifetime as long as 573 ms. Furthermore, the universality of such a calcination-modulated luminescent method has been proved by the AFI zeolite matrix. This study offers up a new way to regulate the luminescence of CDs facilitated by matrix, which considerably promotes the potential applications of CDs-based composites in the future.