Material, Size, and Environment Dependence of Plasmon-Induced Hot Carriers in Metallic Nanoparticles

Harnessing hot electrons and holes resulting from the decay of localized surface plasmons in nanomaterials has recently led to new devices for photovoltaics, photo catalysis, 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, whereas transition-metal nanoparticles produce dominantly holes for the oxygen evolution reaction.

利用纳米材料中局域表面等离子体激元衰变产生的热电子和空穴，最近催生了用于光伏、光催化和光电子学的新器件。热载流子的特性具有高度可调性，在这项工作中，我们研究了它们对球形金属纳米粒子的材料、尺寸和环境的依赖性。特别是，我们对六种不同的等离子体材料（钠、钾、铝、铜、银和金）进行了热载流子产生率和能量分布的理论计算。利用准静态近似描述光学性质，并采用球形势阱描述电子结构，通过费米黄金定则描述等离子体激元衰变成热电子 - 空穴对的过程。我们给出了嵌入不同介电介质中、直径最大达40纳米的纳米粒子的研究结果。我们发现，在介电常数大的介质中，直径为16纳米或更小的纳米粒子产生的热载流子最多。在不同的材料中，钠、钾和金产生的热载流子最多。我们还研究了热载流子诱导的水分解，发现简单金属纳米粒子有助于引发析氢反应，而过渡金属纳米粒子主要产生用于析氧反应的空穴。