The development of sensors with high sensitivity, good selectivity and reproducibility are of great importance for the detection of Fe³⁺ in contaminated water for environmental monitoring. In this work, a reflux approach has been adopted to synthesize Ti₃C₂T_x quantum dots (QDs) based on the cutting effect of tetramethylammonium hydroxide (TMAOH) on Ti₃C₂T_x at high temperature. The surface-functionalized Ti₃C₂T_x QDs contained abundant amino groups and exhibited tunable pH-dependent emission, which was attributed to the protonation and deprotonation of the surface terminations. The linearity of the radiometric fluorescence intensity versus pH indicates its great potential as a dual-emission ratiometric pH sensor. Additionally, the Ti₃C₂T_x QDs exhibited tunable excitation-dependent emission behavior, which was related to the degree of passivation by the amino groups on the surface. Furthermore, the fluorescence intensity of the Ti₃C₂T_x QDs shows a linear response toward Fe³⁺ in the nanomolar to micromolar range with a low detection limit of 2 nM, originating from the oxidation and reduction between Fe³⁺ and Ti₃C₂T_x. This ultra-sensitive and selective detection capability demonstrated the environmental application potential for Ti₃C₂T_x QDs as a nanoprobe to monitor Fe³⁺.

中文翻译：

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用于超灵敏 Fe3+ 离子传感的可调谐荧光氨基功能化 Ti3C2Tx MXene 量子点

开发具有高灵敏度、良好选择性和重现性的传感器对于环境监测污染水中Fe ³⁺的检测具有重要意义。本工作基于四甲基氢氧化铵（TMAOH）在高温下对Ti ₃ C ₂ T _x的切割作用，采用回流法合成Ti ₃ C ₂ T _x量子点（QDs） 。表面功能化的 Ti ₃ C ₂ T _x量子点含有丰富的氨基并表现出可调的 pH 依赖性发射，这归因于表面末端的质子化和去质子化。辐射荧光强度与pH 的线性关系表明其作为双发射比率 pH 传感器的巨大潜力。此外，Ti ₃ C ₂ T _x QDs 表现出可调谐的激发依赖性发射行为，这与表面氨基的钝化程度有关。此外，Ti ₃ C ₂ T _x ^{QDs 的荧光强度显示出对 Fe 3+}的线性响应。在纳摩尔至微摩尔范围内，检测限低至 2 nM，源于 Fe ³⁺和 Ti ₃ C ₂ T _x之间的氧化和还原。这种超灵敏和选择性的检测能力证明了 Ti ₃ C ₂ T _x QD 作为纳米探针监测 Fe ³⁺的环境应用潜力。