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arXiv 1802.05096cond-mat.mtrl-sci
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金属纳米粒子中等离子体激元热载流子的材料、尺寸和环境依赖性

Material, size and environment dependence of plasmon-induced hot carriers in metallic nanoparticles

Stefano Dal Forno, Luigi Ranno, Johannes Lischner

摘要:

利用纳米材料中局部表面等离子体激元衰变产生的热电子和空穴,最近导致了用于光电子学、光电子学和光电子学的新器件。热载流子的性质是高度可调的,在这项工作中,我们研究了它们对球形金属纳米颗粒的材料,尺寸和环境的依赖性。特别是,我们进行了理论计算的热载流子产生率和能量分布的六种不同的等离子体材料(钠,钾,铝,铜,银和金)。通过费米黄金法则,使用准静态近似的光学性质和球势阱的电子结构的等离子体衰变成热的电子空穴对。我们目前的结果与直径高达40纳米,这是嵌入在不同的电介质中的纳米粒子。我们发现,小纳米粒子的直径为16 nm或更小的介质中具有大的介电常数产生最热的载流子。在不同的材料中,Na、K和Au产生的热载流子最多。我们还研究了热载流子诱导的水裂解,发现简单的金属纳米颗粒是有用的,用于引发析氢反应,而过渡金属纳米颗粒产生的主要是空穴的析氧反应。

英文摘要:

Harnessing hot electrons and holes resulting from the decay of localized surface plasmons in nanomaterials has recently led to new devices for photovoltaics, photocatalysis and optoelectronics. Properties of hot carriers are highly tunable and in this work we investigate their dependence on the material, size and environment of spherical metallic nanoparticles. In particular, we carry out theoretical calculations of hot carrier generation rates and energy distributions for six different plasmonic materials (Na, K, Al, Cu, Ag and Au). The plasmon decay into hot electron-hole pairs is described via Fermi's Golden Rule using the quasistatic approximation for optical properties and a spherical well potential for the electronic structure. We present results for nanoparticles with diameters up to 40 nm, which are embedded in different dielectric media. We find that small nanoparticles with diameters of 16 nm or less in media with large dielectric constants produce most hot carriers. Among the different materials, Na, K and Au generate most hot carriers. We also investigate hot-carrier induced water splitting and find that simple-metal nanoparticles are useful for initiating the hydrogen evolution reaction, while transition-metal nanoparticles produce dominantly holes for the oxygen evolution reaction.

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