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Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon-supported single atom catalysts focused on nitrogen-doped carbons, which, unlike classic carbon materials, have a fairly well-defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting-edge analytical methods., (© 2024 Wiley-VCH GmbH.)

Microporous molecular crystals are promising materials because of their designable porosity as well as their resistance to chemical and other stimuli. Here, we developed microporous molecular cocrystals by taking advantage of the specific interactions between porphyrins and fullerene molecules. Single-crystal X-ray diffraction analysis revealed that one nickel(II) porphyrin interacts with two fullerene molecules to form a two-dimensional honeycomb network with an eclipsed stacking mode, providing one-dimensional void channels. After the pores were activated by heat treatment or mechanical grinding, the prepared cocrystal can incorporate gas and solvent molecules reversibly while maintaining its single-crystallinity. Also, it retained its single-crystallinity in the presence of water, acid-base, or high pressure. These findings in this study expand the availability of molecular crystals based on intermolecular interactions as porous materials, which are expected to work under conditions that have not been applicable to other molecule-based porous materials., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Co-published by University of Science and Technology of China and American Chemical Society.)

Porous carbons are important electrode materials for supercapacitors. One of the challenges associated with supercapacitors is improving their energy density without relying on pseudocapacitance, which is based on fast redox reactions that often shorten device lifetimes. A possible solution involves achieving high total capacitance (C tot ), which comprises Helmholtz capacitance (C H ) and possibly quantum capacitance (C Q ), in high-surface carbon materials comprising minimally stacked graphene walls. In this work, a templating method is used to synthesize 3D mesoporous graphenes with largely identical pore structures (≈2100 m 2 g -1 with an average pore size of ≈7 nm) but different concentrations of oxygen-containing functional groups (0.3-6.7 wt.%) and nitrogen dopants (0.1-4.5 wt.%). Thus, the impact of the heteroatom functionalities on C tot is systematically investigated in an organic electrolyte excluding the effect of pore structures. It is found that heteroatom functionalities determine C tot , resulting in the cyclic voltammetry curves being rectangular or butterfly-shaped. The nitrogen functionalities are found to significantly enhance C tot owing to increased C Q ., (© 2023 The Authors. Small published by Wiley‐VCH GmbH.)

Metal organic frameworks (MOFs) are a class of porous organic-inorganic crystalline materials that have attracted much attention as H 2 storage devices and catalytic supports. In this paper, the synthesis of highly-dispersed Ni nanoparticles (NPs) for the hydrogenation of olefins was achieved by employing Ni-MOF-74 as a precursor. Investigations of the structural transformation of Ni species derived from Ni-MOF-74 during heat treatment were conducted. The transformation was monitored in detail by a combination of XRD, in situ XAFS, and XPS measurements. Ni NPs prepared from Ni-MOF-74 were easily reduced by the generation of reducing gases accompanied by the decomposition of Ni-MOF-74 structures during heat treatment at over 300 °C under N 2 flow. Ni-MOF-74-300 exhibited the highest activity for the hydrogenation of 1-octene due to efficient suppression of excess agglomerated Ni species during heat treatment. Moreover, Ni-MOF-74-300 showed not only high activity for the hydrogenation of olefins but also high size-selectivity because of the selective formation of Ni NPs covered by MOFs and the MOF-derived carbonaceous layer., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)