Roche Ben, Vo Tamie, Chang Wei-Shun
Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth North Dartmouth Massachusetts 02747 USA
Chem Sci. 2023 Jul 27;14(32):8598-8606. doi: 10.1039/d3sc02167j. eCollection 2023 Aug 16.
Plasmonic nanoparticles have been demonstrated to enhance photocatalysis due to their strong photon absorption and efficient hot-carrier generation. However, plasmonic photocatalysts suffer from a short lifetime of plasmon-generated hot carriers that decay through internal relaxation pathways before being harnessed for chemical reactions. Here, we demonstrate the enhanced photocatalytic reduction of gold ions on gold nanorods functionalized with polyvinylpyrrolidone. The catalytic activities of the reaction are quantified by monitoring of the spectral evolution of single nanorods using a dark-field scattering microscope. We observe a 13-fold increase in the reduction rate with the excitation of d-sp interband transition compared to dark conditions, and a negligible increase in the reduction rate when excited with intraband transition. The hole scavenger only plays a minor role in the photocatalytic reduction reaction. We attribute the enhanced photocatalysis to an efficient charge separation at the gold-polyvinylpyrrolidone interface, where photogenerated d-band holes at gold transfer to the HOMO of polyvinylpyrrolidone, leading to the prolonged lifetime of the electrons that subsequently reduce gold ions to gold atoms. These results provide new insight into the design of plasmonic photocatalysts with capping ligands.
由于其强烈的光子吸收和高效的热载流子产生，等离子体纳米颗粒已被证明可增强光催化作用。然而，等离子体光催化剂存在等离子体产生的热载流子寿命短的问题，这些热载流子在用于化学反应之前就通过内部弛豫途径衰减了。在此，我们展示了用聚乙烯吡咯烷酮功能化的金纳米棒上金离子的光催化还原增强。通过使用暗场散射显微镜监测单个纳米棒的光谱演变来量化反应的催化活性。我们观察到，与黑暗条件相比，通过d-sp带间跃迁激发时还原速率提高了13倍，而通过带内跃迁激发时还原速率的增加可忽略不计。空穴清除剂在光催化还原反应中仅起次要作用。我们将增强的光催化作用归因于金-聚乙烯吡咯烷酮界面处的有效电荷分离，在该界面处，金上光生的d带空穴转移到聚乙烯吡咯烷酮的最高占据分子轨道，从而延长了随后将金离子还原为金原子的电子的寿命。这些结果为具有封端配体的等离子体光催化剂的设计提供了新的见解。
