Synthesis of double carbon dots co-doped mesoporous Al2O3 for ratiometric fluorescent determination of oxygen

Abstract

A new type of ratiometric fluorescent sensor was fabricated in a facile and low-cost process via sequentially assembling blue-light-emitting luminescent carbon dots (BCDs) and red-light-emitting carbon dots (RCDs) into the pores of mesoporous aluminas (MAs) through hydrogen band interactions. The advantages of the resultant BCDs/RCDs/MAs co-doped materials are that their luminescence exhibits dual characteristic peaks of the BCDs and RCDs under a single excitation wavelength, and that they having high surface-to-volume ratios. The co-doped materials were monitored in different carbon dioxide (CO2), oxygen (O2), nitrogen (N2), and water vapor (H2O) environments. Based on the energy transfer from the RCDs to BCDs, with the addition of oxygen, the characteristic fluorescence intensity of the RCDs is monotonically quenched, but that of the BCDs remains almost unchanged. These results allow for the fabrication of a ratiometric fluorescent sensor using BCDs as reference fluorophores, and RCDs as target sensitive fluorophores. The as-prepared ratiometric fluorescence sensor has a high sensitivity with a linear oxygen volume range from 0 to 100, and exhibits an extremely short response/regeneration time of 2–4s. The BCDs/RCDs/MAs co-doped materials are highly sensitive and selective for the detection of oxygen.