Stabilizing Few-Atom Platinum Clusters by Zinc Single-Atom-Glue for Efficient Anti-Markovnikov Alkene Hydrosilylation.

Few-atom metal clusters (FAMCs) exhibit superior performance in catalyzing complex molecular transformations due to their special spatial environments and electronic states, compared to single-atom catalysts (SACs). However, achieving the efficient and accurate synthesis of FAMCs while avoiding the formation of other species, such as nanoparticles and SACs, still remains challenges. Herein, we report a two-step strategy for synthesis of few-atom platinum (Pt) clusters by predeposition of zinc single-atom-glue (Zn1) on MgO nanosheets (Ptn-Zn1/MgO), where FAMCs can be obtained over a wide range of Pt contents (0.09 to 1.45 wt %). Zn atoms can act as Lewis acidic sites to allow electron transfer between Zn and Pt through bridging O atoms, which play a crucial role in the formation and stabilization of few-atom Pt clusters. Ptn-Zn1/MgO exhibited a high selectivity of 93 % for anti-Markovnikov alkene hydrosilylation. Moreover, an excellent activity with a turnover frequency of up to 1.6×104 h-1 can be achieved, exceeding most of the reported Pt SACs. Further theoretical studies revealed that the Pt atoms in Ptn-Zn1/MgO possess moderate steric hindrance, which enables high selectivity and activity for hydrosilylation. This work presents some guidelines for utilizing atomic-scale species to increase the synthesis efficiency and precision of FAMCs.

Alleviating OH Blockage on the Catalyst Surface by the Puncture Effect of Single-Atom Sites to Boost Alkaline Water Electrolysis.

Nonprecious transition metal catalysts have emerged as the preferred choice for industrial alkaline water electrolysis due to their cost-effectiveness. However, their overstrong binding energy to adsorbed OH often results in the blockage of active sites, particularly in the cathodic hydrogen evolution reaction. Herein, we found that single-atom sites exhibit a puncture effect to effectively alleviate OH blockades, thereby significantly enhancing the alkaline hydrogen evolution reaction (HER) performance. Typically, after anchoring single Ru atoms onto tungsten carbides, the overpotential at 10 mA·cm-2 is reduced by more than 130 mV (159 vs 21 mV). Also, the mass activity is increased 16-fold over commercial Pt/C (MA100 = 17.3 A·mgRu-1 vs 1.1 A·mgPt-1, Pt/C). More importantly, such electrocatalyst-based alkaline anion-exchange membrane water electrolyzers can exhibit an ultralow potential (1.79 Vcell) and high stability at an industrial current density of 1.0 A·cm-2. Density functional theory (DFT) calculations reveal that the isolated Ru sites could weaken the surrounding local OH binding energy, thus puncturing OH blockage and constructing bifunctional interfaces between Ru atoms and the support to accelerate water dissociation. Our findings exhibit generality to other transition metal catalysts (such as Mo) and contribute to the advancement of industrial-scale alkaline water electrolysis.

Spiral Square Nanosheets Assembled from Ru Clusters.

Spiral two-dimensional (2D) nanosheets exhibit unique physical and chemical phenomena due to their twisted structures. While self-assembly of clusters is an ideal strategy to form hierarchical 2D structures, it is challenging to form spiral nanosheets. Herein, we first report a screw dislocation involved assembled method to obtain 2D spiral cluster assembled nanosheets (CANs) with uniform square morphology. The 2D spiral Ru CANs with a length of approximately 4 µm and thickness of 20.7 ± 3.0 nm per layer were prepared via the assembly of 1-2 nm Ru clusters in the presence of molten block copolymer Pluronic F127. Cryo-electron microscopy (cryo-EM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) demonstrate the existence of screw dislocation in the spiral assembled structure. The X-ray absorption fine structure spectrum indicates that Ru clusters are Ru3+ species, and Ru atoms are mainly coordinated with Cl with a coordination number of 6.5. Fourier-transform infrared (FT-IR) spectra and solid-state nuclear magnetic resonance hydrogen spectra (1H NMR) indicate that the assembly process of Ru clusters is formed by noncovalent interactions, including hydrogen bonding and hydrophilic interactions. Additionally, the Ru-F127 CANs exhibit excellent photothermal conversion performance in the near-infrared (NIR) region.