ZrS₂量子点: 制备, 结构及光学特性

In recent years, transition metal chalcogenides (TMDs) have attracted extensive attention of researchers due to their unique electronic structure and excellent photoelectric properties. In this paper, hexagonal structure 1T-ZrS₂ quantum dots (QDs) having a monodisperse grain size of around 3.1 nm is prepared by the ultrasonic exfoliation method. The preparation includes the following steps: ZrS₂ powder is ground, followed by ultrasonic exfoliation in 1-methyl-2-pyrrolidone (NMP), and 1T-ZrS₂ QDs are collected after centrifugation. The structure, morphology and optical properties of the QDs are studied in detail. The structure, morphology, size distribution, and elemental composition of 1T-ZrS₂ QDs are studied by using X-ray diffractometer (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The chemical bonds of 1T-ZrS₂ QDs are characterized by X-ray photoelectron microscopy (XPS) and Fourier transform infrared spectrometer (FTIR). The TEM and AFM results show that the 1T-ZrS₂ QDs are spherical in shape with uniform size distribution. The sizes of the 1T-ZrS₂ QDs follow a Gaussian fitted distribution with an average diameter of W_C=3.1 nm and the FWHM is 1.3 nm. The XRD diffraction pattern of 1T-ZrS₂ QDs show wide dispersed diffraction peaks, which is the characteristic of QDs. The diffraction peak at 2θ=32.3°(d=0.278 nm) corresponds to the (101) crystal plane, and the weak diffraction peak at 2θ=56.8°(d=0.167 nm) belongs to the (103) crystal plane. The grain size is also calculated by using the Debye-Scherrer formula, and the calculated value (2.9 nm) is consistent with the result of TEM (3.1 nm). Two Raman vibration modes (E_1g and A_1g) are observed. The E_1g (507.3 cm^-1) and A_1g (520.1 cm^-1) modes relate to the in-plane and out-of-plane vibration respectively. The Raman intensity of the A_1g vibration mode is stronger than that of E_1g. The UV-Vis and photoluminescence (PL and PLE) characterizations exhibit that the 1T-ZrS₂ QDs have two UV absorption peaks at 283 nm and 336 nm, respectively. The Stokes shift is ~130 nm, the fluorescence quantum yield reaches up to 53.3%. The results show that the 1T-ZrS₂ QDs have the excellent fluorescence performance and unique optical properties, which make the 1T-ZrS₂ QDs an important material for developing photodetectors, multi-color luminescent devices, and other devices.