Rational design of long wavelength solid-state fluorescent carbon dots based on zirconium

As a new type of zero dimensional carbon based fluorescent nanomaterial, carbon dots (CDs) have been studied and developed for many years. Various methods have been explored to prepare multicolor CDs to achieve tunable fluorescence of CDs. However, synthesizing fluorescent CDs located in the long wavelength emission region remains a challenge. Here, through a simple one-step solvothermal method using anhydrous citric acid (CA) as the raw material, ZrCl4 as both a metal element dopant and an inorganic salt matrix, and NH3·H2O as nitrogen source, Zr-doped CDs (Zr-CDs) solution with long wavelength fluorescence emission and solid powders with blue fluorescence can be obtained simultaneously. By optimizing the usage of ZrCl4, the fluorescence emission of the prepared CDs red shifted from 596 nm to 650 nm. The introduction of Zr4+ can cause a significant redshift. In addition, based on the sensitivity of CDs to oxygen, they can be used for the detection of trace amounts of H2O2. When using metal-organic framework (MOF) to encapsulate the Zr-CDs which is in the solution, optically stable CD@MOF powders can be obtained, which can be used for the construction of red light-emitting diodes (LEDs), demonstrating its potential application in the field of solid-state lighting. The synthesis technology is expected to provide favorable technical support for the future development of CDs.