Novel non-covalent interactions involved with the Al₁₃M cluster (M = Li, Na, K, Cu, Ag, Au)

<div><p>The complexes of Al₁₃M cluster (M = Li, Na, K, Cu, Ag, Au) and Lewis bases NH₃, H₂O, C₆H₆, and HLi have been predicted and characterised. The results showed that the cluster Al₁₃M forms the alkali-bonding or coinage metal-bonding interaction through M with these Lewis bases. These complexes exhibit some similarities and differences in the structures, properties, and nature with conventional molecules. The formation of these interactions has a negligible or small effect on the structures of Al₁₃M. This study combines the cluster Al₁₃M with non-covalent interactions, which is of great importance in supramolecular chemistry.</p></div

Intrinsic Mechanism for Carbon Dioxide Methanation over Ru-Based Nanocatalysts

Ruthenium-based supported catalysts are of great potential for CO2 methanation, while the catalytic mechanisms remain elusive owing to the conjunction of the metal size and support effect, as well as the possible strong metal/support interactions (SMSI) in a practical catalyst. Herein, with the deposition of alumina over the Ru/SiC model nanocatalysts by the method of the atomic layer deposition (ALD) technique, the corrugated (1011) surface of Ru nanoparticles can be selectively insulated due to its preference for alumina deposition, and the intrinsic activity of CO2 conversion was confirmed to depend crucially on the residual planar (0001) surface. Characterizations including in situ infrared spectroscopy (IR) combined with density functional theory (DFT) calculation and the microkinetic modeling revealed that the competitive kinetics of H2 and CO2 activation on the Ru surface governs the activity and selectivity of methanation. The terrace sites of Ru nanocatalysts serve as the genuine active site through the HCOO* intermediate with the surface occupied by the H* species for further methanation. The (1011) surface suffers from a lower capability for hydrogenation due to its preference toward CO2 adsorption and results in the surface poisoning by the *C and *CH species, which thus makes it a negligible contribution toward methanation over Ru nanocatalysts. However, the presence of the alumina overlayer on the corrugated surface also improves the stability of the Ru nanocatalyst, to keep its activity even at a high temperature pretreatment. Our results demonstrate the terrace sites as the intrinsic active sites for CO2 methanation and also deepen insights on the catalytic mechanism of CO2 transformation over Ru-based nanocatalysts

Metallic Cobalt Encapsulated in Bamboo-Like and Nitrogen-Rich Carbonitride Nanotubes for Hydrogen Evolution Reaction

Despite being technically possible, the hydrogen production by means of electrocatalytic water splitting is still practically unreachable mainly because of the lack of inexpensive and high active catalysts. Herein, a novel and facile approach by melamine polymerization, exfoliation and Co²⁺-assisted thermal annealing is developed to fabricate Co nanoparticles embedded in bamboo-like and nitrogen-rich carbonitride nanotubes (Co@NCN). The electronic interaction between the embedded Co nanoparticles and N-rich carbonitride nanotubes could strongly promote the HER performance. The optimized Co@NCN-800 exhibits outstanding HER activity with an onset potential of −89 mV (vs RHE), a large exchange current density of 62.2 μA cm^–2, and small Tafel slope of 82 mV dec^–1, as well as excellent stability (5000 cycles) in acid media, demonstrating the potential for the replacement of Pt-based catalysts. Control experiments reveal that the superior performance should be ascribed to the synergistic effects between embedded Co nanoparticles and N-rich carbonitride nanotubes, which originate from the high pyridinic N content, fast charge transfer rate from Co particles to electrodes via electronic coupling, and porous and bamboo-like carbonitride nanotubes for more active sites in HER

In Situ Synthesis of Core–Shell Pt–Cu Frame@Metal–Organic Frameworks as Multifunctional Catalysts for Hydrogenation Reaction

Controllable integration of metal nanoparticles (NPs) and metal–organic frameworks (MOFs) is of significant importance in many applications owing to their unique properties. In situ efficient synthesis of metal NPs with different structures into MOFs is a great challenge. Herein, we report the nanostructures of octahedron and flower Pt–Cu frame@HKUST-1, which is successfully synthesized under a microwave irradiation method in only 30 min. In this study, Pt–Cu alloys, serving as the self-template, are synthesized first, followed by the HKUST-1 shell growing in situ via the consumption of Cu⁰. As multifunctional catalysts, the core–shell structures exhibit excellent performance for the hydrogenation of 1-hexene. Notably, octahedron Pt–Cu frame@HKUST-1 displays high turnover number (TON) and turnover frequency (TOF) of 1004 and 2008 h^–1, respectively. Thanks to the protective effect of HKUST-1, the octahedron Pt–Cu frame@HKUST-1 can be recycled for at least four runs without serious loss of activity and obvious aggregation of Pt–Cu alloys. Furthermore, the size-selective catalysis is also well-demonstrated by choosing 1-hexene, <i>cis</i>-cyclooctene, and styrene as substrates