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Bimetallic single–atom catalysts (b–SACs) have recently gained prominence by virtue of the unique catalytic cooperative interactions they can exhibit, intertwining electronic and geometric effects. To date, research efforts have exclusively focused on direct mechanisms such as electron density transfer or sequential reactivity. Herein, the first study on indirect, coordination–induced catalytic synergies in carbon‐supported RuPt SACs is conducted. To this end, a holistic approach is developed, combining i) precision synthesis, ii) advanced characterization, iii) exploration of single–site adsorption properties via the hydrogen evolution reaction, and iv) modeling through density functional theory. Despite the lack of both intermetallic coordination in the first or second shell and charge redistribution effects, the RuPt SACs exhibit a H2 formation rate enhanced up to 15–fold compared with their monometallic counterparts. To unfold the origin of the intermetallic cooperativity, modifications of the structural and catalytic properties induced by the integration of a second metal species are investigated. Thus, Pt atoms are found to selectively occupy the most energeticallyfavorable cavities in the support, prompting Ru atoms to assume a distinct, more active, configuration. This contribution unveils a novel principle of bimetallic cooperativity, demonstrating the key role of integrative experimental and computational analyses in studying b–SACs. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) exhibits unique properties as a support for single-atom heterogeneous catalysts (SAHCs). Understanding how the synthesis method, carrier properties, and metal identity impact the isolation of metal centers is essential to guide their design. This study compares the effectiveness of direct and postsynthetic routes to prepare SAHCs by incorporating palladium, silver, iridium, platinum, or gold in g-C3N4 of distinct morphology (bulk, mesoporous and exfoliated). The speciation (single atoms, dimers, clusters, or nanoparticles), distribution, and oxidation state of the supported metals are characterized by multiple techniques including extensive use of aberration-corrected electron microscopy. SAHCs are most readily attained via direct approaches applying copolymerizable metal precursors and employing high surface area carriers. In contrast, although post-synthetic routes enable improved control over the metal loading, nanoparticle formation is more prevalent. Comparison of the carrier morphologies also points toward the involvement of defects in stabilizing single atoms. The distinct metal dispersions are rationalized by density functional theory and kinetic Monte Carlo simulations, highlighting the interplay between the adsorption energetics and diffusion kinetics. Evaluation in the continuous three-phase semihydrogenation of 1-hexyne identifies controlling the metal-carrier interaction and exposing the metal sites at the surface layer as key challenges in designing efficient SAHCs. [ABSTRACT FROM AUTHOR]

An exact knowledge of the architecture of complex pore networks and the impact on transport processes is critical to understand and optimize their integration in many functional solids. Here, a robust and versatile approach is demonstrated to quantitatively map pore constrictions within hierarchical faujasite-type (Y and USY) zeolites, the most widely applied zeolitic materials in industry. Differential hysteresis scanning measurements by high-resolution argon sorption coupled with an advanced modeling framework enable the derivation of the amount and size of pyramidal, constricted, and occluded mesopores. This yields unprecedented insight into the impact of widely practiced demetallation treatments on the porosity evolution and clearly highlights the interplay between the geometry of mesopores developed by a given treatment and those introduced by previously applied postsynthetic modifications. Based on the findings, the dynamic assessment by positron annihilation spectroscopy confirms the effectiveness of each mesopore type at enhancing the diffusion of ortho-positronium within the crystal. The quantitative descriptors attained by these complementary techniques can revolutionize the design of porous materials for a wide range of applications. [ABSTRACT FROM AUTHOR]

Active site coordination, bimetallic systems, cooperativity effects, single-atom catalysts By selectively occupying the most energetically favorable cavities in the carbon host, Pt atoms drive Ru atoms to assume a distinct, more active configuration. Keywords: active site coordination; bimetallic systems; cooperativity effects; single-atom catalysts EN active site coordination bimetallic systems cooperativity effects single-atom catalysts 1 1 1 12/27/22 20221222 NES 221222 B Bimetallic Single Atom Catalysts b In article number 2206513, Javier Pérez-Ramírez, Núria López and co-workers investigate cooperativity mechanisms between fully isolated Ru and Pt atoms via the hydrogen evolution reaction, demonstrating that catalytic synergies can arise in the absence of direct metal-metal interactions. [Extracted from the article]

The principle of integral metal-organic framework (MOF) reconstruction is demonstrated for differently degraded HKUST-1 via a facile, one-step, solvent-assisted treatment. Controlled MOF degradation by exposure to 77% humidity, liquid water, and diluted hydrochloric acid produces a mixture of non-porous crystalline hybrid materials containing protonated linker and copper-oxo species, which are then reconstructed back into high-quality HKUST-1 by contacting them with ethanol. X-ray diffraction and sorption kinetics reveal a true memory effect of the system from completely degraded materials. The reconstruction approach is consequently extrapolated to gas- and liquid-phase treatments in a fixed-bed reactor with ethanol and ethanol/water mixtures for use in CO2 capture from a simulated pre-combustion gas stream. Up to a maximum of 94% porosity and 85% CO2 sorption capacity can be recovered from a steamed material. A degradation-reconstruction model is put forward based on X-ray diffraction observations and structural analyses, microscopy, N2 sorption, thermogravitry-mass spectrometry and IR spectroscopy observations, particularly elucidating the influence of various degradation pathways on the reconstruction. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles are deposited on the surface of highly magnetic carbon-coated cobalt nanoparticles. In contrast to the established synthesis of Pd nanoparticles via reduction of Pd(II) precursors, the microwave decomposition of a Pd(0) source leads to a more efficient Pd deposition, resulting in a material with considerably higher activity in the hydrogenation of alkenes. Systematic variation of the Pd loading on the carbon-coated cobalt nanoparticle surface reveals a distinct trend to higher activities with decreased loading of Pd. The activity of the catalyst is further improved by the addition of 10 vol% Et2O to iso-propanol that is found to be the solvent of choice. With respect to activity (turnover frequencies up to 11 095 h−1), handling, recyclability through magnetic decantation, and leaching of Pd (≤6 ppm/cycle), this novel magnetic hybrid material compares favorably to conventional Pd/C or Pd@CNT catalysts. [ABSTRACT FROM AUTHOR]

Mass transfer in zeolite crystals can be enhanced by the introduction of a hierarchical network of auxiliary mesopores. To fully exploit pore engineering in the design of more efficient industrial catalysts, the benefit needs to be demonstrated over technically relevant forms. Here, the influence of shaping on the adsorption and diffusion properties of hierarchical ZSM‐5 is assessed by studying the gravimetric uptake of 2,2‐dimethylbutane over powders and millimeter‐sized bodies. Formed by extrusion or granulation with clay binders, the latter display a complex trimodal network of micro‐, meso‐, and macropores. The enhanced intracrystalline diffusivity due to the interconnected mesopores is preserved in the macroscopic bodies, independent of the shaping method or binder applied. Furthermore the superior overall diffusivity is retained in the hierarchical bodies compared to their conventional (purely microporous) counterparts, despite the significant extracrystalline resistance to mass transfer. The connective participation of mesopores, leading to a 6 times improved effective diffusivity in hierarchical with respect to conventional zeolite powders, is revealed by the distinct dependence on the adsorbate concentration and the relationship with the mesopore surface area. Analysis of the thermodynamic parameters derived from the adsorption isotherm proves a sensitive method to detect binder‐zeolite interactions induced upon shaping. [ABSTRACT FROM AUTHOR]

Hierarchical FAU- and LTA-type catalysts are prepared by post-synthetic modifications and evaluated in the base-catalyzed Knoevenagel condensation of benzaldehyde with malononitrile. A novel route to attain mesoporous Al-rich zeolites (A and X) is demonstrated, while mesoporous Y and USY zeolites are prepared using recently developed methods. Base functionality is introduced by alkali ion exchange (Cs, Na) or by high-temperature nitridation in ammonia. A thorough characterization of the zeolites' structure, composition, porosity, morphology, and basicity demonstrates that the presence of a secondary mesopore network enhances the ion-exchange efficiency and the structural incorporation of nitrogen. The modified USY zeolites display twice the conversion, while the hierarchical A, X, and Y are up to 10 times more active based on the enhanced accessibility. These results demonstrate that the Knoevenagel condensation takes place predominately at the external surface, highlighting secondary porosity as a key criterion in the design of basic zeolite catalysts. [ABSTRACT FROM AUTHOR]

In article number 1605785, Javier Pérez‐Ramírez and co‐workers investigate the synthesis of single‐atom heterogeneous catalysts based on precious metals and using graphitic carbon nitride as the carrier. Advanced characterization and simulations reveal the impact of the carrier properties, and of the metal identity and method of introduction on the speciation. Controlling the metal‐carrier interaction and exposing the reactive metal centers are key for maximizing the potential of these materials. [ABSTRACT FROM AUTHOR]

On page 5621, J. Kenvin, J. Pérez‐Ramírez, and coworkers demonstrate differential hysteresis scanning by high‐resolution argon sorption and positron annihilation spectroscopy as powerful tools to quantify the complex architecture of pore networks in hierarchical faujasite zeolites and their efficiency in transport processes. The descriptors attained by these complementary techniques further advance the design of porous materials for a wide range of applications. The creatures in the cover, exploring a tortious cave system, exemplify the challenges with pore accessibility and connectivity. [ABSTRACT FROM AUTHOR]

On page 3855, J. Pérez‐Ramírez and co‐workers demonstrate the reconstruction of water‐degraded HKUST‐1, one of the most studied metal–organic frameworks, by means of facile, one‐step, solvent‐assisted treatments. This regeneration process is symbolized by the phoenix, the long‐lived bird from Greek mythology that obtains new life by arising from the ashes of its predecessor. Marcel Reich (marcelreich.com) is acknowledged for creating the lovely cover artwork. [ABSTRACT FROM AUTHOR]

On page 1923 Javier Pérez‐Ramírez and co‐workers establish methods involving acid and optionally base treatments to prepare hierarchical FAU and LTA‐type zeolites. By conquering the latter Al‐rich frameworks, the full compositional and topological flexibility desired in the design of hierarchical zeolites by post‐synthetic strategies is accomplished. Upon functionalization, the mesoporous X, Y, and A zeolites display superior performance as base catalysts. Carolina Flores is acknowledged for perfecting the cover artwork. [ABSTRACT FROM AUTHOR]