Plate-like CDots/EuBDC nanocomposite for ratiometric luminescence thermometry

Abstract

The synthesis of dual-emission nanocomposite materials has emerged as an excellent strategy for designing new and advanced luminescent ratiometric thermometers. In the present work, a dual-emission nanocomposite material based on carbon dots (CDots), with chitosan as the precursor, and Europium–Organic Framework (CDots/EuBDC) was prepared, through ultrasonic synthesis, and applied as a ratiometric thermometer. Whereas the as-synthesized nanocomposite maintains the crystalline structure of EuBDC, its thermal stability increases and the surface area decreases due to the CDots incorporation. The ratio of the CDots/EuBDC emission intensities (I_CDots/I_Eu) is temperature-dependent in the 293 to 348 K range, in which the intensity of the Eu^{3+ 5}D₀ → ⁷F₂ transition works as a reference signal. The CDots/EuBDC luminescent thermometer shows a maximum relative thermal sensitivity of 1.58% K⁻¹ at 293 K and a colorimetric temperature response with (x, y) CIE color coordinates ranging from blue (0.36, 0.27), at 293 K, to orange (0.43, 0.30), at 343 K.