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 H₂–D₂ 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.

来自金属纳米结构表面等离子体激元的光诱导热载流子已被证明是非常有前途的光催化试剂。虽然非热热载流子和热化热载流子都可能对这一过程做出贡献，但它们在任何给定化学反应中的具体作用通常尚未确定。在这里，我们报告了 Cu 纳米颗粒光催化的 H ₂ –D ₂交换反应主要由热化热载流子驱动的观察结果。外部量子产率表现出有趣的 S 形强度依赖性，并且在高光强度下超过 100%，这表明热载流子倍增发挥了作用。热化热载流子量子产率的简化模型再现了观察到的反应动力学特征，验证了我们对热化热载流子机制的假设。量子力学研究表明，表面 Cu-H 键的振动激发是可能的激活机制，进一步支持低能热化热载流子在光催化该反应中的有效性。