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The ring-opening polymerization of L-lactide is a crucial route for producing biodegradable polylactides (PLAs). Developing an efficient catalyst for this process poses significant challenges. Herein, we report the successful incorporation of nickel during the crystallization of ZIF-67, the derivation of the abundant and stable CoO source, to obtain the composite magnetic Ni@CoO@ZIF-67 using the solid-state thermal (SST) method. The characterization of the resulting materials revealed that nickel atoms are well dispersed in the composite CoO@ZIF-67, imparting additional magnetic properties. The composite Ni@CoO@ZIF-67 demonstrated superior performance as a heterogeneous catalyst for the ring-opening polymerization of L-lactide compared to reference materials such as Ni-Hmim, CoO, ZIF-67, and CoO@ZIF-67. Furthermore, the magnetic property of Ni@CoO@ZIF-67 offers practical advantages, enabling easier separation and recycling of the catalyst. Notably, the SST method facilitates the single-step synthesis of composite magnetic Ni@CoO@ZIF-67 under solvent-free conditions, representing a significant advancement in catalyst development. This approach not only simplifies the synthesis process but also inspires further developments of heterogeneous magnetic catalysts for a variety of effective and diverse reactions. [ABSTRACT FROM AUTHOR]

Single-atom iron electrocatalysts have emerged as up-and-coming alternatives to platinum-based catalysts for the oxygen reduction reaction. However, their further development has been impeded by complex fabrication procedures and limitations in long-term stability. This study developed a chemical vapor deposition approach for synthesizing an efficient iron single-atom electrocatalyst denoted as Fe-SA@NC, utilizing vaporized ferrocene to deposit on a hierarchical N-doped carbon derived from ZIF-8. The preparation process maintained the initial pore structure throughout the deposition process by utilizing a two-step pyrolysis, preventing the collapse or deformation of the pore structure and frameworks. The optimized catalyst exhibited an exceptional half-wave potential (0.932 V) and kinetic current density (28.38 mA cm−2 at 0.9 V vs. RHE), along with high turnover frequency (36.37 s−1) and mass activity (5.68 A mg−1), and remarkable long-term stability in an alkaline electrolyte, exceeding those of commercial Pt/C and most previously reported iron-based electrocatalysts. Moreover, it also demonstrated outstanding practicability in both liquid and solid Zn–air batteries. The formation of well-dispersed Fe–N4 with strong interaction on hierarchical N-doped carbon was verified in the correlation of the structural activity and the excellent performance of Fe-SA@NC. This work sheds some light on the facile synthesis of single-atom catalysts with effective efficiency and stability. [ABSTRACT FROM AUTHOR]

α-Hydroxy ketones are a class of vital organic skeletons that generally exist in a variety of natural products and high-value chemicals. However, the traditional synthetic route for their production involves toxic Hg salts and corrosive H2SO4 as catalysts, resulting in harsh conditions and the undesired side reaction of Meyer–Schuster rearrangement. In this study, CO2-promoted hydration of propargylic alcohols was achieved for the synthesis of various α-hydroxy ketones. Notably, this process was catalyzed using an environmentally friendly and cost-effective biomass-based ionic liquids/CuCl system, which effectively eliminated the side reaction. The ionic liquids utilized in this system are derived from natural biomass materials, which exhibited recyclability and catalytic activity under 1 bar of CO2 pressure without volatile organic solvents or additives. Evaluation of the green metrics revealed the superiority of this CuCl/ionic liquid system in terms of environmental sustainability. Further mechanistic investigation attributed the excellent performance to the ionic liquid component, which exhibited multifunctionality in activating substrates, CO2 and the Cu component. [ABSTRACT FROM AUTHOR]

Adsorption of H2 on functionalized graphite slit-pore at 77 and 298 K was investigated by using a grand canonical Monte Carlo simulation. The physical pore width in a range of micropores was studied. We plotted the adsorbed amount and heat contributions as a function of pore width and pressure. We found that the pore width, pore volume, and functional group play a key role in H2 uptake in different conditions. Pore widths of 0.65 and 1.0 nm are the optimum widths and play an important role at low pressures while the total pore volume is the key at higher pressures in H2 gravimetric capacity at a wide temperature range of 77–298 K. However, functional group properties do not play a significant role in H2 adsorption capacity at 298 K. They play a significant role and become more pronounced at a lower temperature (< 298 K) during low pressures until the functional group becomes saturated by adsorbate. The results obtained with different force fields confirm that N-doped porous carbons are more effective than O-doped porous carbons for enhanced H2 storage. The heat contribution between H2 and functional group type is divided into three levels base on the values which is in the order of quaternary-N/pyridinic-N-oxide > pyrrolic-N/carboxyl > hydroxyl/carbonyl. Moreover, the adsorbed amount and all the heats of the higher concentration of functional group are higher than that of lower concentration of functional group. The saturation of the higher concentration of functional group occurs at a higher pressure, thereby indicating the wider pressure range of enhanced H2 storage. This work provided a new strategy to develop the optimum pore width and suitable functional group type for enhancing H2 storage in porous carbons. [ABSTRACT FROM AUTHOR]

The metal-organic frameworks (MOFs) attract interest as potential catalysts whose catalytic properties are driven by defects. Several methods have been proposed for the defects-inducing synthesis of MOFs. However, the active species formed on the defective sites remain elusive and uncharacterized, as the spectroscopic fingerprints of these species are hidden by the regular structure signals. In this work, we have performed the synthesis of ZIF-8 MOF with defect-inducing procedures using fully deuterated 2-methylimidazolate ligands to enhance the defective sites' visibility. By combining 1H and 31P MAS NMR spectroscopy and X-ray absorption spectroscopy, we have found evidence for the presence of different structural hydroxyl Zn-OH groups in the ZIF-8 materials. It is demonstrated that the ZIF-8 defect sites are represented by Zn-OH hydroxyl groups with the signals at 0.3 and -0.7 ppm in 1H MAS NMR spectrum. These species are of basic nature and may be responsible for the catalytic activity of the ZIF-8 material., (© 2024 Wiley‐VCH GmbH.)