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Single‐atom heterogeneous catalysts (SACs) hold promise as sustainable alternatives to metal complexes in organic transformations. However, their working structure and dynamics remain poorly understood, hindering advances in their design. Exploiting the unique features of droplet‐based microfluidics, we present the first in‐situ assessment of a palladium SAC based on exfoliated carbon nitride in Suzuki–Miyaura cross‐coupling using X‐ray absorption spectroscopy. Our results confirm a surface‐catalyzed mechanism, revealing the distinct electronic structure of active Pd centers compared to homogeneous systems, and providing insights into the stabilizing role of ligands and bases. This study establishes a valuable framework for advancing mechanistic understanding of organic syntheses catalyzed by SACs. [ABSTRACT FROM AUTHOR]

Solar‐driven transfer hydrogenation of unsaturated bonds has received considerable attention in the research area of sustainable organic synthesis; however, water, the ultimate green source of hydrogen, has rarely been investigated due to the high barrier associated with splitting of water molecules. We report a carbon‐nitride‐supported palladium single‐atom heterogeneous catalyst with unparalleled performance in photocatalytic water‐donating transfer hydrogenation compared to its nanoparticle counterparts. Isotopic‐labeling experiments and operando nuclear magnetic resonance measurements confirm the direct hydrogenation mechanism using in situ‐generated protons from water splitting under visible‐light irradiation. Density functional theory calculations attribute the high activity to lower barriers for hydrogenation, facilitated desorption of ethylbenzene, and facile hydrogen replenishment from water on the atomic palladium sites. [ABSTRACT FROM AUTHOR]

Chemical modifiers enhance the efficiency of metal catalysts in numerous applications, but their introduction often involves toxic or expensive precursors and complicates the synthesis. Here, we show that a porous boron nitride carrier can directly modify supported palladium nanoparticles, originating unparalleled performance in the continuous semi‐hydrogenation of alkynes. Analysis of the impact of various structural parameters reveals that using a defective high surface area boron nitride and ensuring a palladium particle size of 4–5 nm is critical for maximizing the specific rate. The combined experimental and theoretical analyses point towards boron incorporation from defects in the support to the palladium subsurface, creating the desired isolated ensembles determining the selectivity. This practical approach highlights the unexplored potential of using tailored carriers for catalyst design. [ABSTRACT FROM AUTHOR]

Ligand-modified palladium nanoparticles deposited on a carbon carrier efficiently catalyze the direct synthesis of H2O2 and the unique performance is due to their hybrid nanostructure. Catalytic testing demonstrated that the selectivity increases with the HHDMA ligand content from 10 % for naked nanoparticles up to 80 %, rivalling that obtained with state-of-the-art bimetallic catalysts (HHDMA=C20H46NO5P). Furthermore, it remains stable over five consecutive reaction runs owing to the high resistance towards leaching of the organic moiety, arising from its bond with the metal surface. As rationalized by density functional theory, this behavior is attributed to the adsorption mode of the reaction intermediates on the metal surface. Whereas they lie flat in the absence of the organic shell, their electrostatic interaction with the ligand result in a unique vertical configuration which prevents further dissociation and over-hydrogenation. These findings demonstrate the importance of understanding substrate-ligand interactions in capped nanoparticles to develop smart catalysts for the sustainable manufacture of hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Wir beschreiben die Herstellung und das Hydrierungsverhalten eines Einzelatom ‐ Palladiumkatalysators, geschaffen durch die Verankerung von Pd ‐ Atomen in den Mesoporen eines graphitischen Kohlenstoffnitridpolymers. Die Analyse des Materials bestätigt die atomare Dispersion der Palladium ‐ Phase über die komplette Probe. Gegenüber nanopartikelbasierten Vergleichskatalysatoren zeigte sich die hohe Aktivität und Selektivität deutlich bei Anwendung in der kontinuierlichen Drei ‐ Phasen ‐ Hydrierung von Alkinen und Nitroarenen in einem Durchflussreaktor. Dichtefunktionalrechnungen ermöglichten die Erarbeitung fundamentaler Erkenntnisse betreffend Materialstruktur und erlaubten, die hohe katalytische Aktivität und Selektivität auf die einfache Wasserstoffaktivierung und Kohlenwasserstoffadsorption auf den atomar verteilten Pd ‐ Strukturen zurückzuführen. Ein (geschütztes) Atom genügt: Die einzigartige Porenstruktur von Kohlenstoffnitriden ermöglicht die stabile Einlagerung isolierter Palladiumatome. Dieser heterogene „Single ‐ site”︁ ‐ Katalysator für selektive Hydrierungen übertrifft die modifizierten Palladium ‐ Nanopartikel, welche den derzeitigen Stand der Technik darstellen. [ABSTRACT FROM AUTHOR]

Aufgestanden für die Selektivität! In ihrer Zuschrift auf S. 1801 ff. zeigen Pérez‐Ramírez et al. die hervorragende Selektivität von Liganden‐modifizierten Pd‐Nanopartikeln bei der direkten H2O2‐Synthese. Die Hybridstruktur macht die Absorption des OOH‐Intermediats auf der Oberfläche möglich und verhindert ungewünschte Dissoziations‐ und Überhydrierungspfade. Durch elektrostatische Wechselwirkungen, dargestellt von den haltenden Fäden der Pinocchio‐Marionette, mit dem Liganden wird die Konfiguration stabilisiert. [ABSTRACT FROM AUTHOR]

Viele Vögel bauen Nester …︁ …︁, um ihre Eier auszubrüten und ihre Jungen in geschützter Umgebung großzuziehen. In ihrer Zuschrift auf S. 11417 ff. verwenden J. Pérez ‐ Ramírez, N. López et al. ein “Nestbau ‐ Konzept” für die Einlagerung isolierter Palladiumatome in den Poren von graphitischem Kohlenstoffnitrid. Dies führt zu einem hervorragenden heterogenen “Single ‐ Site” ‐ Katalysator für Hydrierungsreaktionen (Titelbildkonzept: Amalia Gallardo, Illustration: Marcel Reich). [ABSTRACT FROM AUTHOR]