Fe Cations Control the Plasmon Evolution in CuFeS 2 Nanocrystals
Fe Cations Control the Plasmon Evolution in CuFeS 2 Nanocrystals
复制标题
Fe 阳离子控制 CuFeS 2 纳米晶体中的等离子体激元演化
DOI：
10.1021/acs.chemmater.0c03829
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发表时间：
2021
影响因子：
8.6
通讯作者：
Robinson, Richard D.
中科院分区：
文献类型：
--
作者：
Yao, Yuan;Bhargava, Anuj;Robinson, Richard D.
与传统的贵金属纳米晶体相比，等离子体半导体纳米晶体具有较宽的光谱范围（可见到红外）和较强的可调性，已成为研究纳米等离子体效应的一个有吸引力的途径。cufes2是一种令人兴奋的半导体，在可见光范围内（~ 498 nm）具有显著的等离子体吸收带。先前的工作报告了这种材料中存在等离子体带和阳离子氧化态的相互矛盾的说法。在这项工作中，我们回答了这些悬而未决的问题，并通过一系列的x射线吸收光谱和x射线发射光谱来表征反应的成核和生长阶段，从而确定cufes2等离子体行为的起源。我们发现等离子体的形成是由Fe2+掺入纳米晶体引起的带结构改变驱动的。与DFT研究预测的纯Cu1+/Fe3+相反，观察到Cu1+/Cu2+和Fe2+/Fe3+的混合氧化态，表明黄铜矿相（CuFeS2）根据合成条件包含一系列氧化态。根据我们的综合结果，我们提出了cufes2合成的反应机理，并概述了一种验证材料相纯度的方法。综上所述，本研究为通过合成时间和温度等多种途径改变阳离子氧化态来调节等离子体激元强度提供了理论基础。
Plasmonic semiconductor nanocrystals have become an appealing avenue for researching nanoscale plasmonic effects due to their wide spectral range (visible to infrared) and great tunability compared to traditional precious metal nanocrystals. CuFeS2is an exciting semiconductor that has a prominent plasmon absorption band in the visible range (∼498 nm). Previous work has reported conflicting accounts of the existence of the plasmon band and the cation oxidation states in this material. In this work, we answer these outstanding questions and determine the origin of the plasmonic behavior in CuFeS2by characterizing the nucleation and growth stages of the reaction through a series ofex situandin situprobes (e.g., X-ray absorption spectroscopy and X-ray emission spectroscopy). We show that the plasmon formation is driven by the band structure modification from Fe2+incorporation into the nanocrystals. As opposed to the pure Cu1+/Fe3+predicted by DFT studies, a mixed oxidation state of Cu1+/Cu2+and Fe2+/Fe3+is observed, indicating that the chalcopyrite phase (CuFeS2) encompasses a range of oxidation states depending on the synthesis conditions. From our combined results, we propose a reaction mechanism for the CuFeS2synthesis and outline a method to verify the phase purity of the material. Overall, this study provides a theoretical basis for tuning plasmon intensity by changing the cation oxidation state through various routes such as synthesis time and temperature.