Strategic design of gold nanocatalysts for effective photocatalytic organic transformation.

We demonstrate the design strategy of free-standing Au nanocatalysts by correlating their physicochemical characteristics with photocatalytic performance. By tailoring the particle size and surface characteristics, we found that small Au nanocatalysts called Au nanoclusters with discrete energy levels are more effective than large metallic Au nanoparticles, while the microenvironments (e.g., charge status and hydrophilicity/hydrophobicity) around the surface of Au-nanoclusters are crucial in determining the performance. With the optimized Au nanocatalyst, under visible light, decarboxylative radical addition reactions for C-C bond formation (i.e., Giese reaction) were first achieved with high yields and further utilized for the preparation of one of the bioactive γ-aminobutyric acid derivatives, pregabalin (Lyrica®), demonstrating its potential in pharmaceutical applications.

Decreasing Hydrogen Content within Zirconium Using Au and Pd Nanoparticles as Sacrificial Agents under Pressurized Water at High Temperature.

Decreasing hydride-induced embrittlement of zirconium-based cladding is a significant challenge for the successful dry storage of spent nuclear fuel. Herein, to radically minimize hydride-induced embrittlement, we used nanoparticles as sacrificial agents with a greater affinity than zirconium for hydrogen. Corrosion experiments in the presence of gold (Au) and palladium (Pd) nanoparticles under simulated pressurized water reactor (PWR) conditions revealed that the hydrogen content of the zirconium samples was remarkably reduced, with a maximum decrease efficiency of 53.9% using 65 nm Au and 53.8% using 50 nm Pd nanoparticles. This approach provides an effective strategy for preventing hydride-induced embrittlement of zirconium-based cladding.

Efficient charge transfer in an aggregation-induced nanocavity of Au nanoclusters.

In the last 20 years, extensive research has been reported on the use of plasmonic nanoparticles as a potential photocatalyst. However, the low conversion efficiency has still remained a major concern. Herein, we present a new photocatalytic reaction system based on Au nanoclusters (Au NCs) to enhance the conversion efficiency. Negatively charged Au NCs electrostatically interact with positively charged metal ions and form highly aggregated nanocrystals, which can efficiently capture a chemical substance in the reaction mixture. In such a reaction system, the distance between the electron donor and acceptor can be shortened, resulting in an efficient electron transfer process. We examined the electron transfer behavior in a nanocavity system via resazurin photoreduction and compared the reaction rate with that of a colloidal system, which is a commonly used reaction system. Evidently, the nanocavity system facilitated an enhanced reaction rate compared to that of the colloidal system. Furthermore, this nanocavity reaction system permitted multistep photoreactions and multi-electron transfer processes.