Sun Mengqi, Wang Ankai, Zhang Min, Zou Shengli, Wang Hui
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States.
ACS Nanosci Au. 2024 Aug 30;4(5):360-373. doi: 10.1021/acsnanoscienceau.4c00035. eCollection 2024 Oct 16.
Photoexcited nonthermal electrons and holes in metallic nanoparticles, known as hot carriers, can be judiciously harnessed to drive interesting photocatalytic molecule-transforming processes on nanoparticle surfaces. Interband hot carriers are generated upon direct photoexcitation of electronic transitions between different electronic bands, whereas intraband hot carriers are derived from nonradiative decay of plasmonic electron oscillations. Due to their fundamentally distinct photogeneration mechanisms, these two types of hot carriers differ strikingly from each other in terms of energy distribution profiles, lifetimes, diffusion lengths, and relaxation dynamics, thereby exhibiting remarkably different photocatalytic behaviors. The spectral overlap between plasmon resonances and interband transitions has been identified as a key factor that modulates the interband damping of plasmon resonances, which regulates the relative populations, energy distributions, and photocatalytic efficacies of intraband and interband hot carriers in light-illuminated metallic nanoparticles. As exemplified by the Au-Cu alloy nanoparticles investigated in this work, both the resonant frequencies of plasmons and the energy threshold for the -to- interband transitions can be systematically tuned in bimetallic alloy nanoparticles by varying the compositional stoichiometries and particle sizes. Choosing photocatalytic degradation of Rhodamine B as a model reaction, we elaborate on how the variation of the particle sizes and compositional stoichiometries profoundly influences the photocatalytic efficacies of interband and intraband hot carriers in Au-Cu alloy nanoparticles under different photoexcitation conditions.
金属纳米颗粒中的光激发非热电子和空穴，即所谓的热载流子，可以被明智地利用，以驱动纳米颗粒表面有趣的光催化分子转化过程。带间热载流子是在不同电子能带之间的电子跃迁直接光激发时产生的，而带内热载流子则源自等离子体电子振荡的非辐射衰减。由于它们的光生机制本质上截然不同，这两种类型的热载流子在能量分布轮廓、寿命、扩散长度和弛豫动力学方面彼此显著不同，从而表现出截然不同的光催化行为。等离子体共振与带间跃迁之间的光谱重叠已被确定为调节等离子体共振带间阻尼的关键因素，这一因素调节了光照下金属纳米颗粒中带内和带间热载流子的相对数量、能量分布和光催化效率。以本工作中研究的金 - 铜合金纳米颗粒为例，通过改变组成化学计量比和颗粒尺寸，可以在双金属合金纳米颗粒中系统地调节等离子体的共振频率以及带间跃迁的能量阈值。选择罗丹明B的光催化降解作为模型反应，我们详细阐述了在不同光激发条件下，颗粒尺寸和组成化学计量比的变化如何深刻影响金 - 铜合金纳米颗粒中带间和带内热载流子的光催化效率。
