Quantitative Understanding of Charge-Transfer-Mediated Fe3+ Sensing and Fast Photoresponse by N-Doped Graphene Quantum Dots Decorated on Plasmonic Au Nanoparticles.,ACS Applied Materials & Interfaces

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Quantitative Understanding of Charge-Transfer-Mediated Fe3+ Sensing and Fast Photoresponse by N-Doped Graphene Quantum Dots Decorated on Plasmonic Au Nanoparticles.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-01-17 , DOI: 10.1021/acsami.9b19067
Ruma Das ₁ , Hiroshi Sugimoto ₂ , Minoru Fujii ₂ , P K Giri _{1,

3}

Affiliation

The formation of a heterostructure with plasmonic nanoparticles drastically alters the optoelectronic properties of graphene quantum dots (GQDs), resulting in exceptional properties. In the present work, we prepare nitrogen-doped GQDs decorated on gold nanoparticles (Au@N-GQDs) by a one-step green reduction method and study its extraordinary fluorescence and photoresponse characteristics. The as-prepared Au@N-GQDs show more than one order of magnitude enhancement in the fluorescence intensity as compared to the bare N-GQDs, which is attributed to hot electron generation and improved absorption in N-GQDs by local field enhancement and the modification of the edge functional groups. Because of the selective coordination to Fe3+ ions, the Au@N-GQDs exhibit extraordinary quenching of fluorescence, with ultrahigh sensitivity for the detection of Fe3+ (<1 nM). A new model for the charge-transfer dynamics is developed involving the Langmuir's law of adsorption to explain the unusual quenching, which strongly deviates from the known models of static/dynamic quenching. The proposed sensor is successfully implemented for the ultrasensitive detection of Fe3+ ions in human serum and Brahmaputra river water samples, representing its high potential applications in clinical as well as environmental diagnosis. Additionally, because of its high absorption in the UV-vis-NIR region and high charge density with long life excitons, the Au@N-GQDs are utilized as photodetectors with ∼104 times faster response than that of bare N-GQDs. The Au@N-GQD-based photodetector possesses a high responsivity of ∼1.36 A/W and a remarkably high external quantum efficiency of ∼292.2%, which is much superior to the GQD-based photodetectors reported till date. The underlying mechanism of ultrafast photoresponse is ascribed to the transfer of hot electrons along with the tunneling of the electrons from Au NPs to N-GQDs as well as the defect reduction of N-GQDs by the incorporation of Au NPs. Without the use of any charge transporting layer, the outstanding performance of N-GQD-based plasmonic photodetector opens up unique opportunities for future high-speed optoelectronic devices.

中文翻译：

通过在等离子金纳米粒子上装饰的N掺杂石墨烯量子点对电荷转移介导的Fe3 +传感和快速光响应的定量理解。

用等离子体纳米颗粒形成异质结构会极大地改变石墨烯量子点（GQD）的光电性能，从而产生出色的性能。在目前的工作中，我们通过一步绿色还原法制备了装饰在金纳米颗粒上的氮掺杂GQD，并研究了其非凡的荧光和光响应特性。所制备的Au @ N-GQDs与裸N-GQDs相比，荧光强度增强了一个数量级以上，这归因于热电子的产生以及局部场增强和N-GQDs对N-GQDs吸收的改善。边缘官能团的修饰。由于对Fe3 +离子的选择性配位，Au @ N-GQD表现出非凡的荧光猝灭，具有超高灵敏度，可检测Fe3 +（<1 nM）。开发了一种新的电荷转移动力学模型，该模型涉及朗格缪尔吸附定律，以解释异常淬灭，该异常极大地偏离了已知的静态/动态淬灭模型。拟议中的传感器已成功用于人血清和雅鲁藏布江河水样品中Fe3 +离子的超灵敏检测，代表了其在临床和环境诊断中的潜在应用。另外，由于Au @ N-GQD在紫外可见-NIR区域具有高吸收率和高电荷密度以及长寿命的激子，因此其光检测器的响应速度是裸N-GQD的约104倍。基于Au @ N-GQD的光电探测器具有约1的高响应度。36 A / W的外部量子效率高达292.2％，远远优于迄今为止报道的基于GQD的光电探测器。超快光响应的潜在机制归因于热电子的转移以及电子从金纳米颗粒到N-GQD的隧穿以及通过掺入金纳米颗粒减少N-GQD的缺陷。在不使用任何电荷传输层的情况下，基于N-GQD的等离子光电探测器的出色性能为未来的高速光电设备打开了独特的机遇。超快光响应的潜在机制归因于热电子的转移以及电子从金纳米颗粒到N-GQD的隧穿以及通过掺入金纳米颗粒减少N-GQD的缺陷。在不使用任何电荷传输层的情况下，基于N-GQD的等离子光电探测器的出色性能为未来的高速光电设备打开了独特的机遇。超快光响应的潜在机制归因于热电子的转移以及电子从金纳米颗粒到N-GQD的隧穿以及通过掺入金纳米颗粒减少N-GQD的缺陷。在不使用任何电荷传输层的情况下，基于N-GQD的等离子光电探测器的出色性能为未来的高速光电设备打开了独特的机遇。

更新日期：2020-01-17

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