Ames Laboratory, U.S. Department of Energy, and Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
J Am Chem Soc. 2014 Jan 29;136(4):1398-408. doi: 10.1021/ja409011y. Epub 2014 Jan 16.
Metal-semiconductor heterostructures are promising visible light photocatalysts for many chemical reactions. Here, we use high-resolution superlocalization imaging to reveal the nature and photocatalytic properties of the surface reactive sites on single Au-CdS hybrid nanocatalysts. We experimentally reveal two distinct, incident energy-dependent charge separation mechanisms that result in completely opposite photogenerated reactive sites (e(-) and h(+)) and divergent energy flows on the hybrid nanocatalysts. We find that plasmon-induced hot electrons in Au are injected into the conduction band of the CdS semiconductor nanorod. The specifically designed Au-tipped CdS heterostructures with a unique geometry (two Au nanoparticles at both ends of each CdS nanorod) provide more convincing high-resolution single-turnover mapping results and clearly prove the two charge separation mechanisms. Engineering the direction of energy flow at the nanoscale can provide an efficient way to overcome important challenges in photocatalysis, such as controlling catalytic activity and selectivity. These results bear enormous potential impact on the development of better visible light photocatalysts for solar-to-chemical energy conversion.
金属-半导体异质结构是许多化学反应有前途的可见光光催化剂。在这里，我们使用高分辨率超局部成像来揭示单 Au-CdS 杂化纳米催化剂表面反应性位点的性质和光催化性质。我们通过实验揭示了两种不同的、与入射能量相关的电荷分离机制，导致在杂化纳米催化剂上形成完全相反的光生反应性位点（e(-)和 h(+)）和不同的能量流。我们发现 Au 中的等离子体诱导热电子注入到 CdS 半导体纳米棒的导带中。具有独特几何形状的专门设计的 Au 尖端 CdS 异质结构（每个 CdS 纳米棒的两端各有两个 Au 纳米颗粒）提供了更有说服力的高分辨率单周转映射结果，并清楚地证明了两种电荷分离机制。在纳米尺度上控制能量流的方向可以为克服光催化中的重要挑战提供一种有效途径，例如控制催化活性和选择性。这些结果对开发用于太阳能-化学能转换的更好的可见光光催化剂具有巨大的潜在影响。
