Efficient Plasmon-Mediated Energy Funneling to the Surface of Au@Pt Core-Shell Nanocrystals.,ACS Nano

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Efficient Plasmon-Mediated Energy Funneling to the Surface of Au@Pt Core-Shell Nanocrystals.
ACS Nano ( IF 15.8 ) Pub Date : 2020-03-13 , DOI: 10.1021/acsnano.0c01653
Christian Engelbrekt _{1,

2} , Kevin T Crampton ₁ , Dmitry A Fishman ₁ , Matt Law ₁ , Vartkess Ara Apkarian ₁

Affiliation

The structure and ultrafast photodynamics of ∼8 nm Au@Pt core–shell nanocrystals with ultrathin (<3 atomic layers) Pt–Au alloy shells are investigated to show that they meet the design principles for efficient bimetallic plasmonic photocatalysis. Photoelectron spectra recorded at two different photon energies are used to determine the radial concentration profile of the Pt–Au shell and the electron density near the Fermi energy, which play a key role in plasmon damping and electronic and thermal conductivity. Transient absorption measurements track the flow of energy from the plasmonic core to the electronic manifold of the Pt shell and back to the lattice of the core in the form of heat. We show that strong coupling to the high density of Pt(d) electrons at the Fermi level leads to accelerated dephasing of the Au plasmon on the femtosecond time scale, electron–electron energy transfer from Au(sp) core electrons to Pt(d) shell electrons on the sub-picosecond time scale, and enhanced thermal resistance on the 50 ps time scale. Electron–electron scattering efficiently funnels hot carriers into the ultrathin catalytically active shell at the nanocrystal surface, making them available to drive chemical reactions before losing energy to the lattice via electron–phonon scattering on the 2 ps time scale. The combination of strong broadband light absorption, enhanced electromagnetic fields at the catalytic metal sites, and efficient delivery of hot carriers to the catalyst surface makes core–shell nanocrystals with plasmonic metal cores and ultrathin catalytic metal shells promising nanostructures for the realization of high-efficiency plasmonic catalysts.

中文翻译：

等离子介导的高效能量流向Au @ Pt核壳纳米晶体的表面。

研究了具有超薄（<3原子层）Pt-Au合金壳的〜8 nm Au @ Pt核壳纳米晶体的结构和超快光动力学，表明它们符合有效的双金属等离子体激元光催化的设计原理。用两种不同的光子能量记录的光电子能谱用于确定Pt–Au壳的径向浓度分布以及费米能量附近的电子密度，这在等离激元阻尼以及电子和热导率中起着关键作用。瞬态吸收测量结果以热量的形式跟踪了从等离激元核心到Pt壳电子歧管再回到核心晶格的能量流。我们表明，在费米能级上与高密度Pt（d）电子的强耦合导致飞秒时间尺度上Au等离子体激元的加速移相，电子-电子能量从Au（sp）核心电子转移到Pt（d）在亚皮秒级的时间范围内提供壳电子，并在50 ps的时间范围内提高热阻。电子-电子散射可将热载流子有效地聚集到纳米晶体表面的超薄催化活性壳中，使它们可用于驱动化学反应，然后通过2 ps的时间通过电子-声子散射将能量损失给晶格。强宽带光吸收，催化金属部位电磁场增强，

更新日期：2020-03-13

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