吉林大学AFM:表面缺陷诱导碳点-NiFe2O4纳米复合材料的光活化：合成、机理及应用

第一作者：吉林大学 Ruyan Xie

通讯作者：吉林大学 邹海峰，吉林大学中日联谊医院 盛世厚

DOI：https://doi.org/10.1002/adfm.202411155

量子点的光学性质受到光活化的显著影响。然而，光活化碳点（CDs）的开发进展仍然停滞不前。本文提出了一种通过NiFe₂O₄修饰在CDs表面引入丰富缺陷，极大地填补光激活CDs的空白，从而制备CDs/NiFe₂O₄的方法。此外，首次提出了一种独特的“OFF-ON-OFF”模式下的荧光检测策略，结合Ag⁺辅助荧光增强，建立了一种双通道调节机制，用于超灵敏检测Hg²⁺。通过增加表面陷阱和非辐射复合，CDs表面缺陷诱导操作为提高光活化能力创造了有利条件。出乎意料的是，CDs/NiFe₂O₄在紫外灯照射后荧光强度增强了25倍。与CDs/NiFe₂O₄相比，Ag⁺辅助光激活CDs/NiFe₂O₄对Hg²⁺的检测具有更高的选择性和灵敏度，检测限低至0.7 nM。此外，通过将CDs/NiFe₂O₄锚定在TiO₂表面成功制备了TiO₂@CDs/NiFe₂O₄催化剂，在可见光照射下，该催化剂在90 min内对四环素进行了高效降解，降解率达到98.3%。这项工作首先为开发高活性光激活CDs技术提供了一种新的缺陷修饰策略，这对未来的环境敏感应用具有重要意义。

Scheme 1. Illustration of the hydrothermal synthesis of CDs/NiFe2O4 and photoactivation fluorescence enhancement process.

Figure 1. A) TEM images (inset: HRTEM image), B) XRD diffractions and C) FT-IR spectrum of CDs/NiFe2O4, D) element mappings, E) XPS surveys, High-resolution spectra including F) C 1s, G) O 1s, H) N 1s, I) Ni 2p and J) Fe 2p of CDs and CDs/NiFe2O4.

Figure 2. A) The UVvis absorption, excitation and emission spectra, B) the 1931 CIE CIE (x, y) chromaticity diagram, C) the 3D contour and D) fluorescence emission spectra within excitation wavelengths ranging from 480–550 nm of CDs/NiFe2O4, fluorescence spectra of E) CDs/NiFe2O4 and F) CDs exposure at different time, G) time-resolved fluorescence decay spectra of freshly prepared CDs/NiFe2O4 and photoactivation CDs/NiFe2O4, H) corresponding images of CDs/NiFe2O4 under UV-light irradiation for 0–11 min, and I) illustration of the photoactivation process.

Figure 3. A) Fluorescence emission spectra and B) the 3D contour of CDs/NiFe2O4 mixed with various concentrations of Hg2+ (0–240 μM), C) the corresponding linear equation between I0/I and Hg2+ concentration (linear interval: 0.001–0.100μM), D) fluorescence emission spectra and E) the 3D contour of Ag-assisted CDs/NiFe2O4 mixed with various concentrations of Hg2+ (0–500 μM) (inset: corresponding images irradiated by UV-lamp), F) the corresponding linear equation between I0/I and Hg2+ concentration (linear interval:1.0–100.0 μM) after the introduction of Ag+, G) fluorescence spectra of Ag+-assisted CDs/NiFe2O4 mixed with different metal cations, H) corresponding intensity ratio of I/I0 and I) images under UV-lamp.

Figure 4. A) UV–vis absorption spectra of Hg2+, CDs/NiFe2O4+Hg2+, and CDs/NiFe2O4+Ag++Hg2+, as well as the excitation spectrum of CDs/NiFe2O4, B) fluorescence decay curve of CDs/NiFe2O4+Hg2+, and C) schematic mechanism of fluorescence quenching of CDs/NiFe2O4 toward Hg2+.

Figure 5. A,B) TEM images taken at different locations, and C) HRTEM image of TiO2@CDs/NiFe2O4, D) XRD diffraction of TiO2@CDs/NiFe2O4 and TiO2, E) XPS survey, and high-resolution spectra of F) N 1s, G) C 1s, H) Ti 2p, I) O 1s.

Figure 6. A) The photocatalytic degradation behaviors of TC using catalysts (TiO2@CDs/NiFe2O4, CDs/NiFe2O4, TiO2 ) and TC self-degradation, B) corresponding k values of TC degradation by TiO2@CDs/NiFe2O4, CDs/NiFe2O4, TiO2 and TC self-degradation, C) UV–vis diffuse spectra, D) curve [F(R)hv]1/2 versus photon energy, E) XPS valence spectra, F) photocurrent responses, G) EIS spectra of the TiO2 and TiO2@CDs/NiFe2O4 samples under visible light irradiation, H) scavenger studies with EDTA-2Na, IPA, BQ and no scavenger, I) the effects of various scavengers on the k values of TiO2@CDs/NiFe2O4 toward TC.

Scheme 2. The proposed mechanism for degradation of TC by TiO2@CDs/NiFe2O4.

Surface Defects-Induced Photoactivation of Carbon Dots-NiFe2O4 Nanocomposite: Synthesis, Mechanism and Applications

https://doi.org/10.1002/adfm.202411155