Department of Chemistry, Rice University, Houston, TX 77005.
Department of Electrical and Computer Engineering, Rice University, Houston, TX 77005.
Proc Natl Acad Sci U S A. 2021 May 18;118(20). doi: 10.1073/pnas.2022109118.
Light-induced hot carriers derived from the surface plasmons of metal nanostructures have been shown to be highly promising agents for photocatalysis. While both nonthermal and thermalized hot carriers can potentially contribute to this process, their specific role in any given chemical reaction has generally not been identified. Here, we report the observation that the H-D exchange reaction photocatalyzed by Cu nanoparticles is driven primarily by thermalized hot carriers. The external quantum yield shows an intriguing S-shaped intensity dependence and exceeds 100% for high light intensities, suggesting that hot carrier multiplication plays a role. A simplified model for the quantum yield of thermalized hot carriers reproduces the observed kinetic features of the reaction, validating our hypothesis of a thermalized hot carrier mechanism. A quantum mechanical study reveals that vibrational excitations of the surface Cu-H bond is the likely activation mechanism, further supporting the effectiveness of low-energy thermalized hot carriers in photocatalyzing this reaction.
已证实，源自金属纳米结构表面等离激元的光致热载流子在光催化中极具应用潜力。虽然非热和热化的热载流子都有可能对此过程做出贡献，但它们在任何特定化学反应中的具体作用通常尚未确定。在此，我们报告了一个观察结果，即由 Cu 纳米颗粒光催化的 H-D 交换反应主要由热化热载流子驱动。外量子效率显示出有趣的 S 形强度依赖性，在高光强下超过 100%，表明热载流子倍增起作用。一个用于热化热载流子量子效率的简化模型再现了反应的观察到的动力学特征，验证了我们关于热化热载流子机制的假设。一项量子力学研究揭示了表面 Cu-H 键的振动激发是可能的激活机制，进一步支持了低能热化热载流子在光催化该反应中的有效性。
