Sub-nanometre sized metal clusters: from synthetic challenges to the unique property discoveries

Facile synthesis of surfactant-free Au cluster/graphene hybrids for high-performance oxygen reduction reaction

Non-Pt noble metal clusters like Au clusters are believed to be promising high performance catalysts for the oxygen reduction reaction (ORR) at the cathode of fuel cells, but they still suffer big problems during the catalysis reactions, such as a large amount of the capping agents being on the surface and easy occurrence of dissolution and aggregation. To overcome these obstacles, here, we present a novel and general strategy to grow ultrafine Au clusters and other metal (Pt, Pd) clusters on the reduced graphene oxide (rGO) sheets without any additional protecting molecule or reductant. Compared with the currently generally adopted nanocatalysts, including commercial Pt/C, rGO sheets, Au nanoparticle/rGO hybrids, and thiol-capped Au clusters of the same sizes, the as-synthesized Au cluster/rGO hybrids display an impressive eletrocatalytic performance toward ORR, for instance, high onset potential, superior methanol tolerance, and excellent stability.

Nucleation products of ligated nanoclusters unaffected by temperature and reducing agent

Atomically uniform nucleation products of ligated metal nanoclusters are observed irrespective of reduction conditions for metal-bidentate ligand systems. Monodentate ligands are not reported to wield similar control, indicating steric contributions of complexing ligands may be as important as their electronic structure for synthesizing small nanoclusters.

Facile synthesis of red-emitting lysozyme-stabilized Ag nanoclusters

A facile approach was developed to prepare positively charged and red-emitting lysozyme-stabilized Ag nanoclusters (Lys-AgNCs) using NaBH₄ as a reducing agent at room temperature. The Lys-AgNCs can be applied in the highly selective detection of Hg²⁺.

Fast Synthesis of Thiolated Au25 Nanoclusters via Protection-Deprotection Method

This letter reports a new synthesis strategy for atomically precise Au nanoclusters (NCs) by using a protection-deprotection method. The key in our synthesis strategy is to introduce a surfactant molecule to protect thiolate-Au(I) complexes during their reduction. The protecting layer provides a good steric hindrance and controls the formation rate of thiolated Au NCs, which leads to the direct formation of atomically precise Au NCs inside the protecting layer. The protecting layer was then removed from the surface of thiolated Au NCs to bring back the original functional groups on the NCs. The protection-deprotection method is simple and facile and can synthesize high-purity thiolated Au25 NCs within 10 min. Our synthesis protocol is fairly generic and can be easily extended to prepare Au25 NCs protected by other thiolate ligands.

Interrogating near-infrared electrogenerated chemiluminescence of Au25(SC2H4Ph)18(+) clusters

The electrochemistry, near-infrared photoluminescence (NIR-PL) spectroscopy, and electrogenerated chemiluminescence (ECL) of Au(25)(SC(2)H(4)Ph)(18)(+)C(6)F(5)CO(2)(-) (Au(25)(+)) clusters were investigated. For the first time, NIR-ECL emission was observed in both annihilation and coreactant paths. Our newly developed spooling spectroscopy was employed during the ECL evolution and devolution processes along with explicit NIR-PL spectroscopy to elucidate light generation mechanisms. It was discovered that the electronic relaxation of the Au(25)(-) excited state to the ground state plays a key role in giving off ECL at 893 nm, while intermediate, strong, and weak NIR-PL emissions at 719/820, 857, and 1080 nm can be attributed to the excited states higher than the HOMO-LUMO gap, across the HOMO-LUMO gap, and of semi-rings, respectively.

Controllable synthesis of gold nanoparticles with ultrasmall size and high monodispersity via continuous supplement of precursor

Synthesis of monodisperse small Au nanoparticles in a controllable manner is of great importance for fundamental science and technical applications. Here, we report a "precursor continuous-supply" strategy for controllable synthesis of 0.9-3.3 nm Au nanoparticles with a narrow size distribution of 0.1-0.2 nm, using a weak reductant to slow-down the reducing rate of AuClPPh(3) precursor in ethanol. Time-dependent X-ray absorption and UV-Vis absorption measurements revealed that owing to the joint use of AuClPPh(3) and ethanol, the remnant AuClPPh(3) was self-supplied and the precursor concentration was maintained at a level near to its equilibrium solubility (ca. 1.65 mmol L(-1)) in ethanol. Hence the nucleation duration was extended that focused the initial size distribution of the Au clusters. With reaction going on for 58 min, most of AuClPPh(3) with a nominal Au concentration of 17.86 mmol L(-1) was converted to ethanol-soluble Au clusters with a size of about 1.0 nm, resulting in a high-yield synthesis.