Gigi Shira, Cohen Tal, Florio Diego, Levi Adar, Stone David, Katoa Ofer, Li Junying, Liu Jing, Remennik Sergei, Camargo Franco V A, Cerullo Giulio, Frenkel Anatoly I, Banin Uri
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
ACS Nano. 2025 Jan 21;19(2):2507-2517. doi: 10.1021/acsnano.4c13603. Epub 2025 Jan 6.
Semiconductor-metal hybrid nanoparticles (HNPs) are promising materials for photocatalytic applications, such as water splitting for green hydrogen generation. While most studies have focused on Cd containing HNPs, the realization of actual applications will require environmentally compatible systems. Using heavy-metal free ZnSe-Au HNPs as a model, we investigate the dependence of their functionality and efficiency on the cocatalyst metal domain characteristics ranging from the single-atom catalyst (SAC) regime to metal-tipped systems. The SAC regime was achieved via the deposition of individual atomic cocatalysts on the semiconductor nanocrystals in solution. Utilizing a combination of electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy, we established the presence of single Au atoms on the ZnSe nanorod surface. Upon increased Au concentration, this transitions to metal tip growth. Photocatalytic hydrogen generation measurements reveal a strong dependence on the cocatalyst loading with a sharp response maximum in the SAC regime. Ultrafast dynamics studies show similar electron decay kinetics for the pristine ZnSe nanorods and the ZnSe-Au HNPs in either SAC or tipped systems. This indicates that electron transfer is not the rate-limiting step for the photocatalytic process. Combined with the structural-chemical characterization, we conclude that the enhanced photocatalytic activity is due to the higher reactivity of the single-atom sites. This holistic view establishes the significance of SAC-HNPs, setting the stage for designing efficient and sustainable heavy-metal-free photocatalyst nanoparticles for numerous applications.
半导体-金属混合纳米粒子（HNPs）是用于光催化应用的有前途的材料，例如用于绿色制氢的水分解。虽然大多数研究都集中在含镉的HNPs上，但实际应用的实现将需要环境兼容的体系。以无重金属的ZnSe-Au HNPs为模型，我们研究了它们的功能和效率对从单原子催化剂（SAC）体系到金属尖端体系的助催化剂金属域特征的依赖性。通过在溶液中半导体纳米晶体上沉积单个原子助催化剂实现了SAC体系。利用电子显微镜、X射线吸收光谱和X射线光电子能谱的组合，我们确定了在ZnSe纳米棒表面存在单个金原子。随着金浓度的增加，这转变为金属尖端生长。光催化产氢测量表明，对助催化剂负载有很强的依赖性，在SAC体系中有一个尖锐的响应最大值。超快动力学研究表明，在SAC或尖端体系中，原始ZnSe纳米棒和ZnSe-Au HNPs具有相似的电子衰减动力学。这表明电子转移不是光催化过程的速率限制步骤。结合结构化学表征，我们得出结论，光催化活性的增强是由于单原子位点的更高反应性。这种整体观点确立了SAC-HNPs的重要性，为设计用于众多应用的高效且可持续的无重金属光催化剂纳米粒子奠定了基础。
