Covalent organic frameworks (COFs) are of interest for many applications originating from their mechanically robust architectures, low density, and high accessible surface area. Depending on their linkers and binding patterns, COFs mainly exhibit microporosity, even though COFs with small mesopores have been reported using extended linkers. For some applications, especially when fast mass transport is desired, hierarchical pore structures are an ideal solution, e.g., with small micropores providing large surface areas and larger macropores providing unhindered transport to and from the materials surface. Herein, we have developed a facile strategy for the fabrication of crystalline COFs with inherent microporosity and template-induced, homogeneously distributed, yet tunable, macroporous structures. This method has been successfully applied to obtain various β-ketoenamine-based COFs with interconnected macro–microporous structures. The as-synthesized macroporous COFs preserve high crystallinity with high specific surface area. When bipyridine moieties are introduced into the COF backbone, metals such as Co2+ can be coordinated within the hierarchical pore structure (macro-TpBpy-Co). The resulting macro-TpBpy-Co exhibits a high oxygen evolution reaction (OER) activity, which is much improved compared to the purely microporous COF with a competitive overpotential of 380 mV at 10 mA/cm2. This can be attributed to the improved mass diffusion properties in the hierarchically porous COF structures, together with the easily accessible active Co2+-bipyridine sites.

The selective oxidation of methane to methanol is a highly challenging target, which is of considerable interest to gain value-added chemicals directly from fuel gas. Copper-containing zeolites, such as Cu/mordenite, have been currently reported to be the most efficient catalysts for this reaction. In this work, it is shown that solid-state ion-exchanged Cu/mordenites exhibit a significantly higher activity for the partial oxidation of methane to methanol than comparable reference catalysts, i.e., Cu/mordenites prepared by the conventional liquid-phase ion exchange procedure. The efficiency of these Cu/mordenites remained unchanged over several successive cycles. From temperature-programmed reduction (TPR) measurements, it can be concluded that the solid-state protocol accelerates Cu exchange at the small pores of mordenite: those are positions where the most active Cu species are presumably located. In situ ultraviolet–visible (UV-vis) spectroscopy furthermore indicates that different active clusters including dicopper- and tricopper-oxo complexes are formed in the catalyst upon oxygen treatment. Notably after activation of methane, different methoxy intermediates seem to be generated at the Cu sites from which one is preferably transformed to methanol by reaction with water. It is furthermore described that the applied reaction conditions have considerable influence on the finally observed methanol production from methane

We present a novel, highly efficient von Hamos spectrometer for X-ray emission spectroscopy (XES) in the laboratory using highly annealed pyrolitic graphite crystals as the dispersive element. The spectrometer covers an energy range from 2.5 keV to 15 keV giving access to chemical speciation and information about the electronic configuration of 3d transition metals by means of the Kβ multiplet. XES spectra of Ti compounds are presented to demonstrate the speciation capabilities of the instrument. A spectral resolving power of E/ΔE = 2000 at 8 keV was achieved. Typical acquisition times range from 10 min for bulk material to hours for thin samples below 1 μm.

For the first time, the manganese gallide (MnGa4) served as an intermetallic precursor, which upon in situ electroconversion in alkaline media produced high‐performance and long‐term‐stable MnOx‐based electrocatalysts for water oxidation. Unexpectedly, its electrocorrosion (with the concomitant loss of Ga) leads simultaneously to three crystalline types of MnOx minerals with distinct structures and induced defects: birnessite δ‐MnO2, feitknechtite β‐MnOOH, and hausmannite α‐Mn3O4. The abundance and intrinsic stabilization of MnIII/MnIV active sites in the three MnOx phases explains the superior efficiency and durability of the system for electrocatalytic water oxidation. After electrophoretic deposition of the MnGa4 precursor on conductive nickel foam (NF), a low overpotential of 291 mV, comparable to that of precious‐metal‐based catalysts, could be achieved at a current density of 10 mA cm−2 with a durability of more than five days.