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Highly active and coking‐resistant Ni catalysts suited for the dry reforming of CH4‐rich gases (70 vol %, e. g. biogas or sour natural gas) were prepared starting from a Mg‐rich Mg−Al hydrotalcite support precursor. Calcination at 1000 °C yields two phases, MgO and MgAl2O4 spinel. Complexation‐deposition of Ni with citric acid on the preformed support as well as lanthanum addition yields a catalyst with remarkably low carbon accumulation over 100 h on stream attributed to both high Ni dispersion and preferred interactions of Ni with MgO on MgAl2O4. [ABSTRACT FROM AUTHOR]

Abstract: A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size‐selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first‐principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano‐aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species. [ABSTRACT FROM AUTHOR]

Catalytic CO oxidation is unveiled on size-selected Pt10 clusters deposited on two very different ultrathin (≈0.5–0.7 nm thick) alumina films: (i) a highly ordered alumina obtained under ultra-high vacuum (UHV) by oxidation of the NiAl(110) surface and (ii) amorphous alumina obtained by atomic layer deposition (ALD) on a silicon chip that is a close model of real-world supports. Notably, when exposed to realistic reaction conditions, the Pt10/UHV-alumina system undergoes a morphological transition in both the clusters and the substrate, and becomes closely akin to Pt10/ALD-alumina, thus reconciling UHV-type surface-science and real-world experiments. The Pt10 clusters, thoroughly characterized via combined experimental techniques and theoretical analysis, exhibit among the highest CO oxidation activity per Pt atom reported for CO oxidation catalysts, due to the interplay of ultra-small size and support effects. A coherent interdisciplinary picture then emerges for this catalytic system. [ABSTRACT FROM AUTHOR]

We report on the manufacture of a state-of-the-art heterogeneous non-noble metal catalyst, which is based on a molecularly well-defined phosphine-tagged cobalt corrole complex. This precursor compound is readily synthesized from convenient starting materials while the active material is obtained through wet-impregnation of the pertinent metalliferous macrocycle onto carbon black followed by controlled pyrolysis of the loaded carrier material under an inert gas atmosphere. Thus, the obtained composite was then applied in the heterogeneous hydrogenation of various nitroarenes to yield a vast array of valuable aniline derivatives that were conveniently isolated as their hydrochloride salts. The introduced catalytic protocol is robust and user-friendly with the entire assembly of the reaction set-up enabling the conduction of the experiments on the laboratory bench without any protection from air. [ABSTRACT FROM AUTHOR]

Heterogeneously catalyzed N‐formylation of amines to formamide with CO2/H2 is highly attractive for the valorization of CO2. However, the relationship of the catalytic performance with the catalyst structure is still elusive. Herein, mixed valence catalysts containing Cu2O/Cu interface sites were constructed for this transformation. Both aliphatic primary and secondary amines with diverse structures were efficiently converted into the desired formamides with good to excellent yields. Combined ex and in situ catalyst characterization revealed that the presence of Cu2O/Cu interface sites was vital for the excellent catalytic activity. Density functional theory (DFT) calculations demonstrated that better catalytic activity of Cu2O/Cu(111) than Cu(111) is attributed to the assistance of oxygen at the Cu2O/Cu interface (Ointer) in formation of Ointer‐H moieties, which not only reduce the apparent barrier of HCOOH formation but also benefit the desorption of the desired N‐formylated amine, leading to high activity and selectivity. [ABSTRACT FROM AUTHOR]

Heterogeneously catalyzed N‐formylation of amines to formamide with CO2/H2 is highly attractive for the valorization of CO2. However, the relationship of the catalytic performance with the catalyst structure is still elusive. Herein, mixed valence catalysts containing Cu2O/Cu interface sites were constructed for this transformation. Both aliphatic primary and secondary amines with diverse structures were efficiently converted into the desired formamides with good to excellent yields. Combined ex and in situ catalyst characterization revealed that the presence of Cu2O/Cu interface sites was vital for the excellent catalytic activity. Density functional theory (DFT) calculations demonstrated that better catalytic activity of Cu2O/Cu(111) than Cu(111) is attributed to the assistance of oxygen at the Cu2O/Cu interface (Ointer) in formation of Ointer‐H moieties, which not only reduce the apparent barrier of HCOOH formation but also benefit the desorption of the desired N‐formylated amine, leading to high activity and selectivity. [ABSTRACT FROM AUTHOR]

A heterogeneous single‐atom catalyst (SAC) based on a tiny Cu loading (0.05 wt.%) supported on CeO2−TiO2 (Ce/Ti=0.18) shows very high Cu mass‐normalized CO oxidation activity, 100 % selectivity for CO2 between 60 and 100 °C and essentially no deactivation during 17 h on stream in the preferential oxidation of CO (PROX) at 120 °C. Based on state of the art, this catalyst is among the most active and PROX‐selective catalysts. Employing a combination of ex‐situ and operando methods, we infer that the isolated Cu single sites are incorporated with redox‐active Cu2+−O−Ce4+⇆Cu+−□−Ce3+ moieties connected by labile oxygen and are exposed on the surface of highly dispersed ceria. This high dispersion is promoted by TiO2 which itself does not participate in redox steps during PROX, as Ti ions remain essentially tetravalent while Cu and Ce undergo reversible redox shuttles. [ABSTRACT FROM AUTHOR]

CO 2 conversion to CO via the reverse water-gas shift (RWGS) reaction is a promising source of syngas for subsequent synthesis of liquid fuels and chemicals. Herein, we present the synthesis of catalysts containing Au supported on hydroxylated Na-modified ZrO 2 , with Au amounts ranging from 0.05 to 1 wt%. Systematic investigations reveal the formation of cooperative Au/Na sites at the interface. These sites cooperate synergistically to activate CO 2 and generate a high surface density of carboxylate-like species, which serve as highly active intermediates for CO formation. It was found that the RWGS reaction on the catalyst with low Au loading proceeds mainly via a carboxylate pathway, with bidentate formate acting as spectators. At higher Au loading, the bidentate formate pathway contributes somewhat to CO formation alongside the carboxylate pathway. Based on temporal analysis of products, we emphasize the significant roles of H 2 spillover and the metal-support interface in the RWGS reaction. [Display omitted] • ZrO2 prepared at high pH with NaOH contains strongly adsorbed surface Na species. • Hydroxylated Na-modified ZrO2 is an excellent support for gold catalysts for RWGS. • Surface Au and Na sites synergistically activate CO2 and boosting CO formation. • In-situ spectroscopic studies reveal carboxylate as active intermediates for RWGS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co/ZrO 2 catalysts with single Co2+ are efficient for C 3 H 8 dehydrogenation to C 3 H 6. • 1Co/ZrO 2 performed durable over multiple dehydrogenation/regeneration cycles. • 1Co/ZrO 2 showed higher activity than a commercial analogue of K-CrO x /Al 2 O 3. • The high activity results from a synergy effect between Co2+ and Zr cus. • Recombination of surface H species is the rate-limiting step in C 3 H 6 formation. Due to the increased production of shale gas containing propane, the share of non-oxidative propane dehydrogenation (PDH) in the large-scale production of propene is expected to continue to grow. There are, however, some ecofriendly and cost shortcomings associated with the currently applied Cr- or Pt-containing catalysts. Against this background, we present here Co/ZrO 2 alternatives and reveal the fundamentals affecting their activity, which can be used for purposeful catalyst design. Co2+ species homogeneously distributed within the lattice of ZrO 2 significantly increase the activity of coordinatively unsaturated Zr4+ for the PDH reaction. The increase is caused by accelerating both the cleavage of CH bonds in propane and the recombination of surface H species, with the latter reaction being the rate-limiting step. The best-performing catalyst outperformed an analogue of commercial K-CrO x /Al 2 O 3 in terms of the rate of propene formation and demonstrated durable performance over a series of 10 PDH/regeneration cycles under industrially relevant conditions. It also outperformed most previously developed Co-containing catalysts in terms of propene productivity. The space–time yield of propene formation achieved at 57 % equilibrium propane conversion at 550 °C was 0.71 kg·h−1·kg cat -1. [ABSTRACT FROM AUTHOR]

[Display omitted] • The formation of self-organized structures depends on the laser scanning strategy. • A high scanning pulse overlap leads to dominating vapor–liquid solid growth. • A high scanning line overlap leads primarily to preferential valley ablation. • Scanning strategy affects crystallinity & chemical composition of microstructures. • Fs-laser treatment can lead to a significant heat-affected-zone (HAZ). This study presents a detailed characterization of self-organized nano- and microstructures on Ti6Al4V evoked by different scanning strategies and fluences with a 300 fs laser operating at a laser wavelength of 1030 nm. The resulting surface morphology was visualized via field emission scanning electron microscopy (FEG-SEM) images of the surface and cross-sections. X-ray diffraction (XRD)-analysis was performed to analyse changes in crystal structures. The chemical surface composition of the near-surface layer was determined by X-ray photoelectron spectroscopy (XPS). Results show a significant influence of heat accumulation while processing with high laser repetition rates on the formation, crystallinity and chemical composition of self-organized structures depending on the scanning strategy. The ablation with different laser scanning strategies led to varying dynamics of growth-mechanisms of self-organized structures, formation of intermetallic phases (Ti 3 Al), sub-oxides and oxides (Ti 6 O, TiO) as well as ions (Ti3+, Ti4+) in surface layer reliant on applied fluence. Furthermore, investigations revealed a heat-affected zone up to several micrometers in non-ablated material. [ABSTRACT FROM AUTHOR]

Using cheap and non-toxic chelating agents during catalyst preparation is considered as an effective tool to control the particle size and to strengthen the metal-support interactions (MSI), while keeping the simplicity of the selected preparation method. The previous properties are useful to improve the catalyst activity, stability, and selectivity in dry reforming of methane (DRM). Therefore, we prepared a series of low Ni loading (2.5 wt%) catalysts supported over MgO-Al 2 O 3 (Mg/Al = 1.3) mixed oxide using the classic wet impregnation method modified with chelating agents (citric acid (CA), tartaric acid (TA) and diethylenetriaminepentaacetic acid (DTPA)) and subsequently evaluated these in DRM. Intensive catalyst characterization (ICP, BET, XRD, XPS, STEM, H 2 -TPR and O 2 -TPO) suggested the presence of different structure-activity relationships. Particularly, using chelating agents during catalyst preparation controlled the final particle size range, which in turn played a pivotal role in shaping the strength of the metal support interactions (MSI). These impacts were crucial to improve the activity, stability and to control the formation of coke deposits. Moreover, special focus was put on the catalytic testing of the outperforming sample (Ni(TA)/Mg 1.3 AlO x) prepared using tartaric acid as chelating agent under severe regimes prone to catalyst deactivation to demonstrate the benefits of the proposed preparation technique. [Display omitted] • Organic ligands affect Ni particle size and its metal-support interaction (MSI). • Adding tartaric acid (TA) during preparation gave the best catalyst. • Up to 60% less coking at high GHSV and excess CH 4. • Ni(TA)/Mg 1.3 AlO x lost only 10% conversion at 600 °C over 50 h runtime. • Ni reoxidation and coke deposition are the main reasons of catalyst deactivation. [ABSTRACT FROM AUTHOR]

• MgO incorporation in ZrO 2 boosts CO 2 methanation activity of Ru/ZrO 2. • The concentration of O-vacancies modulates the stability of intermediates. • Different electronic/adsorptive properties proved by in-situ DRIFT and EPR investigations. O-vacancies are defects commonly correlated with the production of CH 4 by CO 2 hydrogenation on reducible catalysts. Their effect on the stability of active CO ads and its origin is, however, not commonly explored for low Ru-loaded catalysts (Ru < 0.5 wt%). Herein, we investigated two catalysts containing a comparable amount of Ru (≈ 0.4 wt%) on two different zirconia supports: ZrO 2 and ZrO 2 -MgO (2.6 wt%-MgO). The rate of CH 4 formation on Ru/ZrO 2 -MgO is ca. 3-fold higher than on Ru/ZrO 2. Combined results from various ex-situ and in-situ characterization techniques provide evidence supporting the correlation between methane evolution and the extended Ru-support perimeter as well as with changes in the bond strength of intermediates modulated by O-vacancies. This latter effect represents the main difference between the two catalysts since the replacement of Zr4+ by Mg2+ ions in the ZrO 2 lattice promotes the generation of O-vacancies, facilitating electron transfer from them to interfacial Ru sites. This not only enhances H 2 activation but also weakens the stability of adsorbed bidentate formate (b-HCOO- ads), which subsequently decomposes to CO ads and then hydrogenates to CH 4 at the Ru-support perimeter. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metallic Co0 species in situ formed are suggested to be the main active sites for PDH. • CoO x but not Co0 is responsible for the formation of undesired products. • Transformation of CoO x to Co0 depends on the strength of CoO x -support interactions. • Co/Silicalite-1 showed the C 3 H 6 space time yield of 1.50 kg·h−1·kg cat −1 at 550 °C. Although Co-containing catalysts show attractive performance in the non-oxidative propane dehydrogenation to propylene (PDH), their tailored development is hindered by the ambiguity in the kind of active sites (Co0 or Co2+O x) responsible for selective and unselective pathways. Herein, we demonstrate that supported CoO x species expends its lattice oxygen through oxidation of C 3 H 8 to CO 2 /C 3 H 6 and are accordingly transformed into Co0 species. The latter are decisive for the selective dehydrogenation of propane to propylene with high activity. The ability of CoO x to in situ form Co0 is affected by metal-oxide-support interactions (MOSI). In addition to the kind of support, defective OH groups (OH nests) in ZSM-5-type zeolites seem to be relevant for the MOSI effect. In comparison with previous studies highlighting the importance of the size of CoO x species and their acidity for coke formation, we could not establish any direct correlation. Nevertheless, the presence of CoO x seems to be relevant for this undesired reaction because the formation of coke is hindered when CoO x species are transformed to Co0 species. Catalyst acidic sites are responsible for cracking reactions. Thus, the derived mechanistic insights reveal the nature of active sites both for selective and unselective pathways and provide fundamentals for catalyst development. From an industrial viewpoint, the developed Co/Silicalite-1 (Co/S-1) catalyst with the weakest MOSI and accordingly highest fraction of Co0 showed the space time yield of propylene formation of 1.50 kg·h−1·kg cat −1 at 67 % equilibrium propane conversion and propylene selectivity of 95.3 % and the Co-related TOF value of 0.145 s−1 at 550 °C. These both activity values exceed those of the state-of-the-art Co-containing catalysts. The productivity of Co/S-1 is comparable or even higher than that of industrially relevant Pt- or Cr-containing catalysts. [ABSTRACT FROM AUTHOR]

Gold-based catalysts have shown high catalytic activity for reverse water gas shift (RWGS) reactions at low temperatures. Despite extensive studies, the RWGS reaction on Au-based catalysts with very low Au content (< 0.1 wt%) has not yet been investigated. In this study, TiO 2 and ZrO 2 supported gold catalysts with such low gold loading have been synthesized and tested for RWGS. The catalysts were investigated by a series of in/ex-situ characterization techniques, including ICP-OES, XRD, BET, XPS, STEM, STEM-EELS, TAP, in-situ DRIFTS and in-situ EPR. At 250 oC, the Au/TiO 2 catalyst showed almost 10 times higher activity than Au/ZrO 2. In-situ DRIFTS results suggest that the formate mechanism is the predominant mechanism over Au/ZrO 2 , while over Au/TiO 2 the reaction proceeds via the formation of hydroxycarbonyl intermediates. A combined study including STEM, STEM-EELS, XPS, and in-situ EPR suggests that the interfacial Au–O v –Ti3+ sites are responsible for the superior activity of Au/TiO 2. [Display omitted] • Au/TiO 2 exhibited superior activity and CO selectivity. • Ti3+formation and oxygen vacancies on Au/TiO 2 contribute to its superior activity. • The weak adsorption strength of CO is responsible for the superior CO selectivity. • An Oxygen-vacancies-engaged reaction mechanism is proposed for RWGS over Au/ZrO 2. • The decomposition of formate seems to be the rate-limiting step in the CO formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gd, La and Sc improve stability of low Ni content Al 2 O 3 -MgO catalysts in DRM. • Rare earth elements stabilize Ni dispersion and promote CO 2 activation. • Gd sufficiently establishes both effects. • Outstanding stability in excess methane (CH 4 /CO 2 = 2) at 630 and 750 °C. • Successful exceptional long-term tests over 100 h at high space velocity. Biogas consists of a larger part of methane and a smaller part of carbon dioxide. Reforming biogas is highly desirable due to the direct conversion of the two components, yet not possible due to the current state of catalyst development. For such dry reforming of methane-rich gases (CH 4 /CO 2 = 2) we now present catalysts with low Ni loading (2.5 wt%) modified with Gd, Sc, or La. The best catalyst reaches 49% CH 4 conversion and 95% CO 2 conversion at 750 °C. The La-modification only shows limited influence on coking and protection against catalyst deactivation although this catalyst exposed highest basicity. On the other side, Sc- and especially Gd-modified catalysts exposed stronger metal-support interaction and thus enhanced stabilization of fine Ni particles during the reaction, which is critical to preserve high performance in CH 4 -rich DRM. This suppressed carbon deposition and the growth of structured carbon as evidenced by STEM images and TPO of spent catalysts. In this way, exceptionally high specific H 2 productivity (94 l/(g cat ·h)) compared to literature was obtained on Gd-modified catalyst, and, most noteworthy, after extending the time on stream from 8 to 100 h the amount of deposited coke increased only from 3 to 4 wt%. [ABSTRACT FROM AUTHOR]

• Rh supported large pore Zr-MOFs with different pore structure were prepared and characterized. • The catalysts show markedly different catalytic effects in the hydroformylation reaction with different framework types. • All catalysts show superior activity at low rh content as expected from rh single site catalysts. • A markedly impact of the pore structure on selectivity to aldehydes and enones is observed. • Catalytic differences are due to different accessibility of rh located in various framework sites. Three large pore crystalline zirconium-based metal-organic frameworks (Zr-MOFs) of different pore sizes (6–18 Å) and structure were synthesized and used for the preparation of the Rh-supported catalysts Rh@UiO-66, Rh@UiO-67, and Rh@MOF-808. The materials were characterized by XRD, FTIR, SEM/TEM, XPS, and nitrogen adsorption/desorption measurements. The catalytic performance was studied in the hydroformylation of olefins to the corresponding aldehydes. A series of n-alk-1-enes of different chain length was used to study the influence of the pore size and structure. The results show that the Zr-MOF-based catalysts are very active and show high aldehyde selectivity. The superior catalytic properties are assigned to the presence of highly dispersed active Rh sites located at the isolated zirconia moieties and the enhanced accessibility of sites via the large pores. Nevertheless, marked differences in the catalytic performance of the catalysts are observed, which are assigned to the different accessibility of Rh located at various secondary building units. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of highly efficient and stable visible-light-driven photocatalysts for the removal of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water is still a challenge. In this work, Bi 2 MoO 6 (BMO) materials with different morphology were successfully prepared via a simple hydrothermal method by altering the solvent. The morphology of the BMO material is mainly influenced by the solvent used in the synthesis (H 2 O, ethanol, and ethylene glycol or their mixtures) and to a lesser extent by subsequent thermal annealing. BMO with aggregated spheres and nanoplate-like structures hydrothermally synthesized in ethylene glycol (EG) and subsequently calcined at 400 °C (BMO-400 (EG)) showed the highest adsorption capacity and photocatalytic activity compared to other synthesized morphologies. Complete degradation of 2,4-D on BMO upon irradiation with a blue light-emitting diode (LED, λ max = 467 nm) was reached within 150 min, resulting in 2,4-dichlorophenol (2,4-DCP) as the main degradation product. Holes (h + ) and superoxide radicals (⋅O 2 - ) are assumed to be the reactive species observed for the rapid conversion of 2,4-D to 2,4-DCP. The addition of H 2 O 2 to the reaction mixture not only accelerates the degradation of 2,4-DCP but also significantly reduces the total organic carbon (TOC) content, indicating that hydroxyl radicals are crucial for the rapid mineralization of 2,4-D. Under optimal conditions, the TOC value was reduced by 84.5% within 180 min using BMO-400 (EG) and H 2 O 2 . The improved degradation performance of BMO-400 (EG) can be attributed to its particular morphology leading to lower charge transfer resistance, higher electron-hole separation, and larger specific surface area.

Reverse water-gas shift (RWGS) reaction has attracted much attention as a potential approach for CO 2 valorization via the production of synthesis gas, especially over Fe-modified supported Cu catalysts on CeO 2 . However, most studies have focused solely on investigating the RWGS reaction over catalysts with high Cu and Fe loadings, thus leading to an increase in the complexity of the catalytic system and, hence, preventing the gain of any reliable information about the nature of the active sites and reaction mechanism. In this work, a CeO 2 -supported single-atom Cu catalyst modified with iron was synthesized and evaluated for the RWGS reaction. The catalytic results reveal a significant synergistic effect between CuCeO 2 and Fe, demonstrating an activity up to three times higher than the combined catalytic activities of monometallic catalysts (Fe/CeO 2 + CuCeO 2 ) under identical conditions. Various ex situ and in situ/operando techniques are employed to unveil the concealed role of Fe in catalyst activity enhancement. The combined findings from hydrogen temperature-programmed reduction (H 2 -TPR) and operando electron paramagnetic resonance spectroscopy (EPR) reveal that the added Fe predominantly interacts with Cu-containing surface sites, resulting in the stabilization of higher proportions of Cu single sites. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and operando EPR results unveil a synergistic interplay of Fe with Cu-containing sites and CeO x domains, efficiently enhancing both the reoxidation of Cu + in Cu + -O v -Ce 3+ moieties and the reducibility of Ce 4+ in CeO x domains under RWGS conditions. Detailed mechanistic studies reveal that the RWGS reaction predominantly proceeds via the redox mechanism., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Earth abundant metal-based heterogeneous catalysts with highly active and at the same time stable isolated metal sites constitute a key factor for the advancement of sustainable and cost-effective chemical synthesis. In particular, the development of more practical, and durable iron-based materials is of central interest for organic synthesis, especially for the preparation of chemical products related to life science applications. Here, we report the preparation of Fe-single atom catalysts (Fe-SACs) entrapped in N-doped mesoporous carbon support with unprecedented potential in the preparation of different kinds of amines, which represent privileged class of organic compounds and find increasing application in daily life. The optimal Fe-SACs allow for the reductive amination of a broad range of aldehydes and ketones with ammonia and amines to produce diverse primary, secondary, and tertiary amines including N-methylated products as well as drugs, agrochemicals, and other biomolecules (amino acid esters and amides) utilizing green hydrogen., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single-atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non-metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non-metal and metal oxide). Through thorough oxidation state investigations by X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), CO-DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH) x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd-N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Improving the selectivity in the oxidative coupling of methane to ethane/ethylene poses a significant challenge for commercialization. The required improvements are hampered by the uncertainties associated with the reaction mechanism due to its complexity. Herein, we report about 90 % selectivity to the target products at 11 % methane conversion over Gd 2 O 3 -based catalysts at 700 °C using N 2 O as the oxidant. Sophisticated kinetic studies have suggested the nature of adsorbed oxygen species and their binding strength as key parameters for undesired methane oxidation to carbon oxides. These descriptors can be controlled by a metal oxide promoter for Gd 2 O 3 ., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Molecular copper catalysts have emerged as promising candidates for the electrochemical reduction of CO 2 . Notable features of such systems include the ability of Cu to generate C 2+  products and the well-defined active sites that allow for targeted structural tuning. However, the frequently observed in situ formation of Cu nanoclusters has undermined the advantages of the molecular frameworks. It is therefore desirable to develop Cu-based catalysts that retain their molecular structures during electrolysis. In this context, a heterogenized binuclear hydroxo-bridged phenanthroline Cu(II) compound with a short Cu···Cu distance is reported as a simple yet efficient catalyst for electrogeneration of ethylene and other C 2 products. In an aqueous electrolyte, the catalyst demonstrates remarkable performance, with excellent Faradaic efficiency for C 2 products (62%) and minimal H 2 evolution (8%). Furthermore, it exhibits high stability, manifested by no observable degradation during 15 h of continuous electrolysis. The preservation of the atomic distribution of the active sites throughout electrolysis is substantiated through comprehensive characterizations, including X-ray photoelectron and absorption spectroscopy, scanning and transmission electron microscopy, UV-vis spectroscopy, as well as control experiments. These findings establish a solid foundation for further investigations into targeted structural tuning, opening new avenues for enhancing the catalytic performance of Cu-based molecular electrocatalysts., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Catalytic hydrogenations are important and widely applied processes for the reduction of organic compounds both in academic laboratories and in industry. To perform these reactions in sustainable and practical manner, the development and applicability of non-noble metal-based heterogeneous catalysts is crucial. Here, we report highly active and air-stable nickel nanoparticles supported on mesoporous silica (MCM-41) as a general and selective hydrogenation catalyst. This catalytic system allows for the hydrogenation of carbonyl compounds, nitroarenes, N-heterocycles, and unsaturated carbon─carbon bonds in good to excellent selectivity under very mild conditions (room temperature to 80°C, 2 to 10 bar H 2 ). Furthermore, the optimal nickel/meso-silicon dioxide catalyst is reusable (4 cycles) without loss of its catalytic activity.

Low-dimensional materials have unique optical, electronic, mechanical, and chemical properties that make them desirable for a wide range of applications. Nano-scaling materials to confine transport in at least one direction is a common method of designing materials with low-dimensional electronic structures. However, bulk materials give rise to low-dimensional electronic structures when bonding is highly anisotropic. Layered Zintl phases are excellent candidates for investigation due to their directional bonding, structural variety, and tunability. However, the complexity of the structure and composition of many layered Zintl phases poses a challenge for producing phase-pure bulk samples to characterize. Eu 11 Zn 4 Sn 2 As 12 is a layered Zintl phase of significant complexity that is of interest for its magnetic, electronic, and thermoelectric properties. To prepare phase-pure Eu 11- x Na x Zn 4 Sn 2 As 12 , a binary EuAs phase was employed as a precursor, along with NaH. Experimental measurements reveal low thermal conductivity and a high Seebeck coefficient, while theoretical electronic structure calculations reveal a transition from a 3D to 2D electronic structure with increasing carrier concentration. Simulated thermoelectric properties also indicate anisotropic transport, and thermoelectric property measurements confirm the nonparabolicity of the relevant bands near the Fermi energy. Thermoelectric efficiency is known to improve as the dimensionality of the electronic structure is decreased, making this a promising material for further optimization and opening the door to further exploitation of layered Zintl phases with low-dimensional electronic structures for thermoelectric applications., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Heterogeneously catalyzed N-formylation of amines to formamide with CO 2 /H 2 is highly attractive for the valorization of CO 2 . However, the relationship of the catalytic performance with the catalyst structure is still elusive. Herein, mixed valence catalysts containing Cu 2 O/Cu interface sites were constructed for this transformation. Both aliphatic primary and secondary amines with diverse structures were efficiently converted into the desired formamides with good to excellent yields. Combined ex and in situ catalyst characterization revealed that the presence of Cu 2 O/Cu interface sites was vital for the excellent catalytic activity. Density functional theory (DFT) calculations demonstrated that better catalytic activity of Cu 2 O/Cu(111) than Cu(111) is attributed to the assistance of oxygen at the Cu 2 O/Cu interface (O inter ) in formation of O inter -H moieties, which not only reduce the apparent barrier of HCOOH formation but also benefit the desorption of the desired N-formylated amine, leading to high activity and selectivity., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The selective hydrogenation of benzofurans in the presence of a heterogeneous non-noble metal catalyst is reported. The developed optimal catalytic material consists of cobalt-cobalt oxide core-shell nanoparticles supported on silica, which has been prepared by the immobilization and pyrolysis of cobalt-DABCO-citric acid complex on silica under argon at 800 °C. This novel catalyst allows for the selective hydrogenation of simple and functionalized benzofurans to 2,3-dihydrobenzofurans as well as related heterocycles. The versatility of the reported protocol is showcased by the reduction of selected drugs and deuteration of heterocycles. Further, the stability, recycling, and reusability of the Co-nanocatalyst are demonstrated., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)