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Metal‐free synthesis of heterocycles is highly sought after in the pharmaceutical industry and has garnered widespread attention due to eliminating the need to remove trace metal catalysts from the reaction. We report a radical 6‐endo addition method for pyridine synthesis from cyclopropylamides and alkynes under metal‐free conditions. Various terminal and substituted alkynes are inserted as C2 units into cyclopropylamides to synthesize versatile pyridines with 57 examples. Mechanistic investigations and computational studies indicate the unprecedented 6‐endo‐trig addition of vinyl radicals to the imine nitrogen atom rather than the conventional 5‐exo‐trig addition to the imine carbon atom, in which the hypervalent iodine(III) plays a critical role. This reaction easily scales up with excellent functional group compatibility and suits the late‐stage pyridine installation on complex molecules. [ABSTRACT FROM AUTHOR]

Methods for producing drugs directly at the cancer site, particularly using bioorthogonal metal catalysts, are being explored to mitigate the side effects of therapy. Albumin‐based artificial metalloenzymes (ArMs) catalyze reactions in living mice while protecting the catalyst in the hydrophobic pocket. Here, we describe the in situ preparation and application of biocompatible tumor‐targeting ArMs using circulating albumin, which is abundant in the bloodstream. The ArM was formed using blood albumin through the intravenous injection of ruthenium conjugated with an albumin‐binding ligand; the tumor‐targeting unit was conjugated to the ArM using its catalytic activity, and the ArM was transported to the cancer site. The delivered ArM catalyzed a second tagging reaction of the proapoptotic peptide on the cancer surface, successfully suppressing cancer proliferation. This approach, which efficiently leveraged the persisting reactivity twice in vivo, holds promise for future in vivo metal‐catalyzed drug synthesis utilizing endogenous albumin. [ABSTRACT FROM AUTHOR]

The direct construction of metal‐free catalysts on conductive substrates for electrocatalytic organic hydrogenation reactions is significant but still unexplored. Here, learning from the homogeneous molecular catalysts, an organic molecular mimetic metal‐free heterogeneous catalyst is designed and constructed in situ on a graphite flake electrode via a mild electrochemical oxidation‐reduction relay strategy. The as‐prepared −COOH‐ and −OH‐functionalized metal‐free catalyst exhibits an electrocatalytic alkyne semihydrogenation performance with a 72 % Faradaic efficiency, 99 % selectivity and 96 % yield of the alkene product, which is comparable to that of noble metal catalysts. The removal of these oxygen‐containing groups leads to negligible activity. The experimental and calculation results reveal that the origin of the high activity can be assigned to the −COOH and −OH groups on graphite. A flow electrolytic cell delivers ten grams of hydrogenated products with 81 % Faradaic efficiency. This metal‐free catalyst is also suitable for gas‐phase acetylene semihydrogenation and other electrocatalytic hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Precisely controlling the microstructure of supported metal catalysts and regulating metal‐support interactions at the atomic level are essential for achieving highly efficient heterogeneous catalysts. Strong metal‐support interaction (SMSI) not only stabilizes metal nanoparticles and improves their resistance to sintering but also modulates the electrical interaction between metal species and the support, optimizing the catalytic activity and selectivity. Therefore, understating the formation mechanism of SMSI and its dynamic evolution during the chemical reaction at the atomic scale is crucial for guiding the structural design and performance optimization of supported metal catalysts. Recent advancements in in situ transmission electron microscopy (TEM) have shed new light on these complex phenomena, providing deeper insights into the SMSI dynamics. Here, the research progress of in situ TEM investigation on SMSI in heterogeneous catalysis is systematically reviewed, focusing on the formation dynamics, structural evolution during the catalytic reactions, and regulation methods of SMSI. The significant advantages of in situ TEM technologies for SMSI research are also highlighted. Moreover, the challenges and probable development paths of in situ TEM studies on the SMSI are also provided. [ABSTRACT FROM AUTHOR]

Developing non‐platinum group metal catalysts for the sluggish hydrogen oxidation reaction (HOR) is critical for alkaline fuel cells. To date, Ni‐based materials are the most promising candidates but still suffer from insufficient performance. Herein, we report an unconventional hcp/fcc Ni (u‐hcp/fcc Ni) heteronanocrystal with multiple epitaxial hcp/fcc heterointerfaces and coherent twin boundaries, generating rugged surfaces with plenty of asymmetric convex sites. Systematic analyses discover that such convex sites enable the adsorption of *H in unusual bridge positions with weakened binding energy, circumventing the over‐strong *H adsorption on traditional hollow positions, and simultaneously stabilizing interfacial *H2O. It thus synergistically optimizes the HOR thermodynamic process as well as reduces the kinetic barrier of the rate‐determining Volmer step. Consequently, the developed u‐hcp/fcc Ni exhibits the top‐rank alkaline HOR activity with a mass activity of 40.6 mA mgNi−1 (6.3 times higher than fcc Ni control) together with superior stability and high CO‐tolerance. These results provide a paradigm for designing high‐performance catalysts by shifting the adsorption state of intermediates through configuring surface sites. [ABSTRACT FROM AUTHOR]

The formation of carbon‐carbon (C−C) bonds is a cornerstone of organic synthesis. Among various methods to construct Csp2−Csp3 bonds, the reductive Heck reaction between (hetero)aryl halides and alkenes stands out due to its potential efficiency and broad substrate availability. However, traditional reductive Heck reactions are limited by the use of precious metal catalysts and/or limited aryl halide and alkene compatibility. Here, we present an electrochemically mediated, metal‐ and catalyst‐free reductive Heck reaction that tolerates both unactivated (hetero)aryl halides and diverse alkenes such as vinyl boronates and silanes. Detailed electrochemical and deuterium‐labeling studies support that this transformation likely proceeds through a paired electrolysis pathway, in which acid generated by the oxidation of N,N‐diisopropylethylamine (DIPEA) at the anode intercepts an alkyl carbanion formed after radical‐polar crossover at the cathode. As such, this approach offers a sustainable method for the construction of Csp2−Csp3 bonds from (hetero)aryl halides and alkenes, paving the way for the development of other electrochemically mediated olefin difunctionalization reactions. [ABSTRACT FROM AUTHOR]

The cleavage of C−O bonds is one of the most promising strategies for lignin‐to‐chemicals conversion, which has attracted considerable attention in recent years. However, current catalytic system capable of selectively breaking C−O bonds in lignin often requires a precious metal catalyst and/or harsh conditions such as high‐pressure H2 and elevated temperatures. Herein, we report a novel protocol of paired electrolysis to effectively cleave the Cβ−O−4 bond of lignin model compounds and real lignin at room temperature and ambient pressure. For the first time, "cathodic hydrogenolysis of Cβ−O−4 linkage" and "anodic C−H/N−H cross‐coupling reaction" are paired in an undivided cell, thus the cleavage of C−O bonds and the synthesis of valuable triarylamine derivatives could be simultaneously achieved in an energy‐effective manner. This protocol features mild reaction conditions, high atom economy, remarkable yield with excellent chemoselectivity, and feasibility for large‐scale synthesis. Mechanistic studies indicate that indirect H* (chemical absorbed hydrogen) reduction instead of direct electron transfer might be the pathway for the cathodic hydrogenolysis of Cβ−O−4 linkage. [ABSTRACT FROM AUTHOR]

Heterogeneous metal catalysts with bifunctional active sites are widely used in chemical industries. Although their improvement process is typically based on trial‐and‐error, it is hindered by the lack of model catalysts. Herein, we report an effective vacancy‐pair capturing strategy to fabricate 12 heterogeneous binuclear‐site catalysts (HBSCs) comprising combinations of transition metals on titania. During the synthesis of these HBSCs, proton‐passivation treatment and step‐by‐step electrostatic anchorage enabled the suppression of single‐atom formation and the successive capture of two target metal cations on the titanium–oxygen vacancy‐pair site. Additionally, during acetylene hydrogenation at 20 °C, the HBSCs (e.g., Pt1Pd1−TiO2) consistently generated more than two times the ethylene produced by their single‐atom counterparts (e.g., Pd1−TiO2). Furthermore, the Pt1Pd1 binuclear sites in Pt1Pd1−TiO2 were demonstrated to catalyze C2H2 hydrogenation via a bifunctional active‐site mechanism: initially C2H2 chemisorb on the Pt1 site, then H2 dissociates and migrates from Pd1 to Pt1, and finally hydrogenation occurs at the Pt1−Pd1 interface. [ABSTRACT FROM AUTHOR]

The construction of chiral motifs containing nonadjacent stereocenters in an enantio‐ and diastereoselective manner has long been a challenging task in synthetic chemistry, especially with respect to their stereodivergent synthesis. Herein, we describe a protocol that enables the enantio‐ and diastereoselective construction of 1,5/1,7‐nonadjacent tetrasubstituted stereocenters through a Pd/Cu‐cocatalyzed Heck cascade reaction. Notably, a C=C bond relay strategy involving the shift of the π‐allyl palladium intermediate was successfully applied in the asymmetric construction of 1,7‐nonadjacent stereocenters. The current method allows for the efficient preparation of chiral molecules bearing two privileged scaffolds, oxindoles and non‐natural α‐amino acids, with good functional group tolerance. The full complement of the four stereoisomers of products bearing 1,5/1,7‐nonadjacent stereocenters could be readily accessed by a simple combination of two chiral metal catalysts with different enantiomers. [ABSTRACT FROM AUTHOR]

Metal atom catalysts have been among the most important research objects due to their specific physical and chemical properties. However, precise control of the anchoring of metal atoms is still challenging to achieve. Cobalt and iridium atomic arrays formed sequentially ordered stable arrays in graphdiyne (GDY) triangular cavities depending on their intrinsic chemical properties and interactions. The success of this method was attributed to multifunctional integration of GDY, enabling selective growth from one to several atoms and various atomic densities. The bimetallic atom arrays show several advantages resulting from reducibility of acetylene bonds, space limiting effect, incomplete charge transfer between GDY and metal atoms, and sp‐C hybridized triple bond skeleton. This well‐designed system exhibits unprecedented oxygen evolution reaction (OER) performance with a mass activity of 2.6 A mgcat.−1 at a low overpotential of 300 mV, which is 216.6 times higher than the state‐of‐the‐art IrO2 catalyst, and long‐term stability. [ABSTRACT FROM AUTHOR]

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high‐value and high‐volume saturated dicarboxylic acids in high carbon yield of 85.9 % in which the carbon yield of long chain dicarboxylic (C10‐C20) acids can reach 58.9% over cobalt‐doped MCM‐41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short‐chain (C4‐C10) to long‐chain ones (C10‐C20) through changing cobalt loading of MCM‐41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one‐step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids. [ABSTRACT FROM AUTHOR]

Metal phosphides have been hailed as potential replacements for scarce noble metal catalysts in many aspects of the hydrogen economy from hydrogen evolution to selective hydrogenation reactions. But the need for dangerous and costly phosphorus precursors, limited support dispersion, and low stability of the metal phosphide surface toward oxidation substantially lower the appeal and performance of metal phosphides in catalysis. We show here that a 1‐step procedure that relies on safe and cheap precursors can furnish an air‐stable Ni2P/Al2O3 catalyst containing 3.2 nm nanoparticles. Ni2P/Al2O3 1‐step is kinetically competitive with the palladium‐based Lindlar catalyst in selective hydrogenation catalysis, and a loading corresponding to 4 ppm Ni was sufficient to convert 0.1 mol alkyne. The 1‐step synthetic procedure alters the surface ligand speciation of Ni2P/Al2O3, which protects the nanoparticle surface from oxidation, and ensures that 85 % of the initial catalytic activity was retained after the catalyst was stored under air for 1.5 years. Preparation of Ni2P on a variety of supports (silica, TiO2, SBA‐15, ZrO2, C and HAP) as well as Co2P/Al2O3, Co2P/TiO2 and bimetallic NiCoP/TiO2 demonstrates the generality with which supported metal phosphides can be accessed in a safe and straightforward fashion with small sizes and high dispersion. [ABSTRACT FROM AUTHOR]

The adsorbate‐mediated strong metal‐support interaction (A‐SMSI) offers a reversible means of altering the selectivity of supported metal catalysts, thereby providing a powerful tool for facile modulation of catalytic performance. However, the fundamental understanding of A‐SMSI remains inadequate and methods for tuning A‐SMSI are still in their nascent stages, impeding its stabilization under reaction conditions. Here, we report that the initial concentration of oxygen vacancy in oxide supports plays a key role in tuning the A‐SMSI between Ru nanoparticles and defected titania (TiO2‐x). Based on this new understanding, we demonstrate the in situ formation of A‐SMSI under reaction conditions, obviating the typically required CO2‐rich pretreatment. The as‐formed A‐SMSI layer exhibits remarkable stability at various temperatures, enabling excellent activity, selectivity and long‐term stability in catalyzing the reverse water gas‐shift reaction. This study deepens the understanding of the A‐SMSI and the ability to stabilize A‐SMSI under reaction conditions represents a key step for practical catalytic applications. [ABSTRACT FROM AUTHOR]

The adsorbate‐mediated strong metal‐support interaction (A‐SMSI) offers a reversible means of altering the selectivity of supported metal catalysts, thereby providing a powerful tool for facile modulation of catalytic performance. However, the fundamental understanding of A‐SMSI remains inadequate and methods for tuning A‐SMSI are still in their nascent stages, impeding its stabilization under reaction conditions. Here, we report that the initial concentration of oxygen vacancy in oxide supports plays a key role in tuning the A‐SMSI between Ru nanoparticles and defected titania (TiO2‐x). Based on this new understanding, we demonstrate the in situ formation of A‐SMSI under reaction conditions, obviating the typically required CO2‐rich pretreatment. The as‐formed A‐SMSI layer exhibits remarkable stability at various temperatures, enabling excellent activity, selectivity and long‐term stability in catalyzing the reverse water gas‐shift reaction. This study deepens the understanding of the A‐SMSI and the ability to stabilize A‐SMSI under reaction conditions represents a key step for practical catalytic applications. [ABSTRACT FROM AUTHOR]

Supported metal catalysts with appropriate metal‐support interactions (MSIs) hold a great promise for heterogeneous catalysis. However, ensuring tight immobilization of metal clusters/nanoparticles on the support while maximizing the exposure of surface active sites remains a huge challenge. Herein, we report an Ir/WO3 catalyst with a new enrooted‐type MSI in which Ir clusters are, unprecedentedly, atomically enrooted into the WO3 lattice. The enrooted Ir atoms decrease the electron density of the constructed interface compared to the adhered (root‐free) type, thereby achieving appropriate adsorption toward oxygen intermediates, ultimately leading to high activity and stability for oxygen evolution in acidic media. Importantly, this work provides a new enrooted‐type supported metal catalyst, which endows suitable MSI and maximizes the exposure of surface active sites in contrast to the conventional adhered, embedded, and encapsulated types. [ABSTRACT FROM AUTHOR]

Developing stable electrocatalysts with accessible isolated sites is desirable but highly challenging due to metal agglomeration and low surface stability of host materials. Here we report a general approach for synthesis of single‐site Fe electrocatalysts by integrating a solvated Fe complex in conductive macroporous organic networks through redox‐active coordination linkages. Electrochemical activation of the electrode exposes high‐density coordinately unsaturated Fe sites for efficient adsorption and conversion of reaction substrates such as NO3− and H2O. Using the electrode with isolated active Fe sites, electrocatalytic NO3− reduction and H2O oxidation can be coupled in a single cell to produce NH3 and O2 at Faradaic efficiencies of 97 % and 100 %, respectively. The electrode exhibits excellent robustness in electrocatalysis for 200 hours with small decrease in catalytic efficiencies. Both the maximized Fe‐site efficiency and the microscopic localization effect of the conductive organic matrix contribute to the high catalytic performances, which provides new understandings in tuning the efficiencies of metal catalysts for high‐performance electrocatalytic cells. [ABSTRACT FROM AUTHOR]

Catalyst deactivation by sintering and coking is a long‐standing issue in metal‐catalyzed harsh high‐temperature hydrocarbon reactions. Ultrathin oxide coatings of metal nanocatalysts have recently appeared attractive to address this issue, while the porosity of the overlayer is difficult to control to preserve the accessibility of embedded metal nanoparticles, thus often leading to a large decrease in activity. Here, we report that a nanometer‐thick alumina coating of MgAl2O4‐supported metal catalysts followed by high‐temperature reduction can transform a nonporous amorphous alumina overlayer into a porous Mg1‐xAl2Oy crystalline spinel structure with a pore size of 2–3 nm and weakened acidity. The high porosity stems from the restrained Mg migration from the MgAl2O4 support to the alumina overlayer through solid‐state reactions at high temperatures. The resulting Ni/MgAl2O4 and Pt/MgAl2O4 catalysts with a porous crystalline Mg1‐xAl2Oy overlayer achieved remarkably high stability while preserving much higher activity than the corresponding alumina‐coated Ni and Pt catalysts on MgO and Al2O3 supports in the reactions of dry reforming of methane and propane dehydrogenation, respectively. [ABSTRACT FROM AUTHOR]

Achieving active site engineering at the atomic level poses a significant challenge in the design and optimization of catalysts for energy‐efficient catalytic processes, especially for a reaction with two reactants competitively absorbed on catalytic active sites. Herein, we show an example that tailoring the local environment of cobalt sites in a robust metal–organic framework through substituting the bridging atom from −Cl to −OH group leads to a highly active catalyst for oxygen activation in an oxidation reaction. Comprehensive characterizations reveal that this variation imparts drastic changes on the electronic structure of metal centers, the competitive reactant adsorption behavior, and the intermediate formation. As a result, exceptional low‐temperature CO oxidation performance was achieved with T25(Temperature for 25 % conversion)=35 °C and T100 (Temperature for 100 % conversion)=150 °C, which stands out from existing MOF‐based catalysts and even rivals many noble metal catalysts. This work provides a guidance for the rational design of catalysts for efficient oxygen activation for an oxidation reaction. [ABSTRACT FROM AUTHOR]

Cascade radical cyclization constitutes an atom‐ and step‐economic route for rapid assembly of polycyclic molecular skeletons. Although an array of redox‐active metal catalysts has recently shown robust applications in enabling various catalytic cascade radical processes, the use of free organic radical as the catalyst, which is capable of triggering strategically distinct cascades, has rarely been developed. Here, we disclosed that the benzimidazolium‐based N‐heterocyclic carbene (NHC)‐boryl radical is capable of catalyzing cascade cyclization reactions in both intra‐ and intermolecular pathways, assembling [5,5] fused bicyclic and [6,6,6] fused tricyclic molecules, respectively. The catalytic reactions start with the chemo‐ and regioselective addition of the boryl radical catalyst to a tethered alkene or alkyne moiety, followed by either an intramolecular formal [3+2] or an intermolecular [2+2+2] cycloaddition process to construct bicyclo[3.3.0]octane or tetrahydrophenanthridine skeletons, respectively. Eventually, a β‐elimination occurs to release the boryl radical catalyst, completing a catalytic cycle. High to excellent diastereoselectivity is achieved in both catalytic reactions under substrate control. [ABSTRACT FROM AUTHOR]

Combining chemo‐ and biocatalysis enables the design of novel economic and sustainable one‐pot processes for the preparation of industrial chemicals, preferably proceeding in water. While a range of proofs‐of‐concept for the compatibility of such catalysts from these two different "worlds of catalysis" have recently been demonstrated, merging noncompatible chemo‐ and biocatalysts for joint applications within one reactor remained a challenge. A conceptual solution is compartmentalization of the catalytic moieties by heterogenization of critical catalyst components, thus "shielding" them from the complementary noncompatible catalyst, substrate or reagent. Exemplified for a one‐pot process consisting of a metal‐catalyzed Wacker oxidation and enzymatic reduction as noncompatible individual reactions steps, we demonstrate that making use of 3D printing of heterogeneous materials containing Cu as a critical metal component can overcome such incompatibility hurdles. The application of a 3D‐printed Cu‐ceramic device as metal catalyst component allows an efficient combination with the enzyme and the desired two‐step transformation of styrene into the chiral alcohol product with high overall conversion and excellent enantioselectivity. This compartmentalization concept based on 3D printing of heterogenized metal catalysts represents a scalable methodology and opens up numerous perspectives to be used as a general tool also for other related chemoenzymatic research challenges. [ABSTRACT FROM AUTHOR]

The recombination of photogenerated charge carriers severely limits the performance of photoelectrochemical (PEC) H2 production. Here, we demonstrate that this limitation can be overcome by optimizing the charge transfer dynamics at the solid–liquid interface via molecular catalyst design. Specifically, the surface of a p‐Si photocathode is modulated using molecular catalysts with different metal atoms and organic ligands to improve H2 production performance. Co(pda‐SO3H)2 is identified as an efficient and durable catalyst for H2 production through the rational design of metal centers and first/second coordination spheres. The modulation with Co(pda‐SO3H)2, which contains an electron‐withdrawing −SO3H group in the second coordination sphere, elevates the flat‐band potential of the polished p‐Si photocathode and nanoporous p‐Si photocathode by 81 mV and 124 mV, respectively, leading to the maximized energy band bending and the minimized interfacial carrier transport resistance. Consequently, both the two photocathodes achieve the Faradaic efficiency of more than 95 % for H2 production, which is well maintained during 18 h and 21 h reaction, respectively. This work highlights that the band‐edge engineering by molecular catalysts could be an important design consideration for semiconductor–catalyst hybrids toward PEC H2 production. [ABSTRACT FROM AUTHOR]

The electrochemical reductive valorization of CO2, referred to as the CO2RR, is an emerging approach for the conversion of CO2‐containing feeds into valuable carbonaceous fuels and chemicals, with potential contributions to carbon capture and use (CCU) for reducing greenhouse gas emissions. Copper surfaces and graphene‐embedded, N‐coordinated single metal atom (MNC) catalysts exhibit distinctive reactivity, attracting attention as efficient electrocatalysts for CO2RR. This review offers a comparative analysis of CO2RR on copper surfaces and MNC catalysts, highlighting their unique characteristics in terms of CO2 activation, C1/C2(+) product formation, and the competing hydrogen evolution pathway. The assessment underscores the significance of understanding structure–activity relationships to optimize catalyst design for efficient and selective CO2RR. Examining detailed reaction mechanisms and structure‐selectivity patterns, the analysis explores recent insights into changes in the chemical catalyst states, atomic motif rearrangements, and fractal agglomeration, providing essential kinetic information from advanced in/ex situ microscopy/spectroscopy techniques. At the end, this review addresses future challenges and solutions related to today's disconnect between our current molecular understanding of structure–activity‐selectivity relations in CO2RR and the relevant factors controlling the performance of CO2 electrolyzers over longer times, with larger electrode sizes, and at higher current densities. [ABSTRACT FROM AUTHOR]

Unsymmetric organic semiconductors have many advantages such as good solubility, rich intermolecular interactions for potential various optoelectronic applications. However, their synthesis is more challenging due to intricate structures thus normally suffering tedious synthesis. Herein, we report a trisulfur radical anion (S3⋅−) triggered domino thienannulation strategy for the synthesis of dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes (DBTDTs) using readily available 1‐halo‐2‐ethynylbenzenes as starting materials. This domino protocol features no metal catalyst and the formation of six C−S and one C−C bonds in a one‐pot reaction. Mechanistic study revealed a unique domino radical anion pathway. Single crystal structure analysis of unsymmetric DBTDT shows that its unique unsymmetric structure endows rich and multiple weak S⋅⋅⋅S interactions between molecules, which enables the large intermolecular transfer integrals of 86 meV and efficient charge transport performance with a carrier mobility of 1.52 cm2 V−1 s−1. This study provides a facile and highly efficient synthetic strategy for more high‐performance unsymmetric organic semiconductors. [ABSTRACT FROM AUTHOR]

Metal single‐atom catalysts represent one of the most promising non‐noble metal catalysts for the oxygen reduction reaction (ORR). However, they still suffer from insufficient activity and, particularly, durability for practical applications. Leveraging density functional theory (DFT) and machine learning (ML), we unravel an unexpected collective effect between FeN4OH sites, CeN4OH motifs, Fe nanoparticles (NPs), and Fe−CeO2 NPs. The collective effect comprises differently‐weighted electronic and geometric interactions, whitch results in significantly enhanced ORR activity for FeN4OH active sites with a half‐wave potential (E1/2) of 0.948 V versus the reversible hydrogen electrode (VRHE) in alkaline, relative to a commercial Pt/C (E1/2, 0.851 VRHE). Meanwhile, this collective effect endows the shortened Fe−N bonds and the remarkable durability with negligible activity loss after 50,000 potential cycles. The ML was used to understand the intricate geometric and electronic interactions in collective effect and reveal the intrinsic descriptors to account for the enhanced ORR performance. The universality of collective effect was demonstrated effective for the Co, Ni, Cu, Cr, and Mn‐based multicomponent ensembles. These results confirm the importance of collective effect to simultaneously improve catalytic activity and durability. [ABSTRACT FROM AUTHOR]

Current transition alumina catalysts require the presence of significant amounts of toxic, environmentally deleterious dopants for their stabilization. Herein, we report a simple and novel strategy to engineer transition aluminas to withstand aging temperatures up to 1200 °C without inducing the transformation to low‐surface‐area α‐Al2O3 and without requiring dopants. By judiciously optimizing the abundance of dominant facets and the interparticle distance, we can control the temperature of the phase transformation from θ‐Al2O3 to α‐Al2O3 and the specific surface sites on the latter. These specific surface sites provide favorable interactions with supported metal catalysts, leading to improved metal dispersion and greatly enhanced catalytic activity for hydrocarbon oxidation. The results presented herein not only provide molecular‐level insights into the critical factors causing deactivation and phase transformation of aluminas but also pave the way for the development of catalysts with improved activity for catalytic hydrocarbon oxidation. [ABSTRACT FROM AUTHOR]

The atomically dispersed metal catalysts with full atomic utilization and well‐defined site structure hold great promise for various catalytic reactions. However, the single metallic site limits the comprehensive reaction performance in most reactions. Here, we demonstrated a photo‐induced neighbour‐deposition strategy for the precise synthesis of diatomic Ir1Pd1 on In2O3 applied for CO2 hydrogenation to methanol. The proximity synergism between diatomic sites enabled a striking promotion in both CO2 conversion (10.5 %) and methanol selectivity (97 %) with good stability of 100 h run. It resulted in record‐breaking space‐time yield to methanol (187.1 gMeOH gmetal−1 hour−1). The promotional effect mainly originated from stronger CO2 adsorption on Ir site with assistance of H‐spillover from Pd site, thus leading to a lower energy barrier for *HCOO pathway. It was confirmed that this synergistic effect strongly depended on the dual‐site distance in an angstrom scale, which was attributed to weaker *H spillover and less electron transfer from Pd to Ir site as the Pd‐to‐Ir distance increased. The average dual‐site distance was evaluated by our firstly proposed photoelectric model. Thus, this study introduced a pioneering strategy to precisely synthesize homonuclear/heteronuclear diatomic catalysts for facilitating the desired reaction route via diatomic synergistic catalysis. [ABSTRACT FROM AUTHOR]

The synthesis of mono‐N‐methylated aliphatic primary amines has traditionally been challenging, requiring noble metal catalysts and high‐pressure H2 for achieving satisfactory yields and selectivity. Herein, we developed an approach for the selective coupling of methanol and aliphatic primary amines, without high‐pressure hydrogen, using a manganese‐based catalyst. Remarkably, up to 98 % yields with broad substrate scope were achieved at low catalyst loadings. Notably, due to the weak base‐catalyzed alcoholysis of formamide intermediates, our novel protocol not only obviates the addition of high‐pressure H2 but also prevents side secondary N‐methylation, supported by control experiments and density functional theory calculations. [ABSTRACT FROM AUTHOR]

Various nanomaterials as biocatalysts could be custom‐designed and modified to precisely match the specific microenvironment of diseases, showing a promise in achieving effective therapy outcomes. Compared to conventional biocatalysts, single metal atom catalysts (SMACs) with maximized atom utilization through well‐defined structures offer enhanced catalytic activity and selectivity. Currently, there is still a gap in a comprehensive overview of the connection between structures and biocatalytic mechanisms of SMACs. Therefore, it is crucial to deeply investigate the role of SMACs in biocatalysis from the atomic structure level and to elucidate their potential mechanisms in biocatalytic processes. In this minireview, we summarize catalysis regulation methods of SMACs at the atomic structure level, focusing on the optimization of catalytic active sites, coordination environment, and active site‐support interactions, and briefly discuss biocatalytic mechanisms for biomedical applications. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) is a promising approach to achieving sustainable electrical‐to‐chemical energy conversion and storage while decarbonizing the emission‐heavy industry. The carbon‐supported, nitrogen‐coordinated, and atomically dispersed metal sites are effective catalysts for CO generation due to their high activity, selectivity, and earth abundance. Here, we discuss progress, challenges, and opportunities for designing and engineering atomic metal catalysts from single to dual metal sites. Engineering single metal sites using a nitrogen‐doped carbon model was highlighted to exclusively study the effect of carbon particle sizes, metal contents, and M−N bond structures in the form of MN4 moieties on catalytic activity and selectivity. The structure‐property correlation was analyzed by combining experimental results with theoretical calculations to uncover the CO2 to CO conversion mechanisms. Furthermore, dual‐metal site catalysts, inheriting the merits of single‐metal sites, have emerged as a new frontier due to their potentially enhanced catalytic properties. Designing optimal dual metal site catalysts could offer additional sites to alter the surface adsorption to CO2 and various intermediates, thus breaking the scaling relationship limitation and activity‐stability trade‐off. The CO2RR electrolysis in flow reactors was discussed to provide insights into the electrolyzer design with improved CO2 utilization, reaction kinetics, and mass transport. [ABSTRACT FROM AUTHOR]

The development of new methods for enantioselective reactions that generate stereogenic centres within molecules are a cornerstone of organic synthesis. Typically, metal catalysts bearing chiral ligands as well as chiral organocatalysts have been employed for the enantioselective synthesis of organic compounds. In this review, we highlight the recent advances in main group catalysis for enantioselective reactions using the p‐block elements (boron, aluminium, phosphorus, bismuth) as a complementary and sustainable approach to generate chiral molecules. Several of these catalysts benefit in terms of high abundance, low toxicity, high selectivity, and excellent reactivity. This minireview summarises the utilisation of chiral p‐block element catalysts for asymmetric reactions to generate value‐added compounds. [ABSTRACT FROM AUTHOR]

The implementation of supported metal catalysts heavily relies on the synergistic interactions between metal nanoparticles and the material they are dispersed on. It is clear that interfacial perimeter sites have outstanding skills for turning catalytic reactions over, however, high activity and selectivity of the designed interface‐induced metal distortion can also obtain catalysts for the most crucial industrial processes as evidenced in this paper. Herein, the beneficial synergy established between designed Pt nanoparticles and MnO in the course of the reverse water gas shift (RWGS) reaction resulted in a Pt/MnO catalyst having ≈10 times higher activity compared to the reference Pt/SBA‐15 catalyst with >99 % CO selectivity. Under activation, a crystal assembly through the metallic Pt (110) and MnO evolved, where the plane distance differences caused a mismatched‐row structure in softer Pt nanoparticles, which was identified by microscopic and surface‐sensitive spectroscopic characterizations combined with density functional theory simulations. The generated edge dislocations caused the Pt lattice expansion which led to the weakening of the Pt−CO bond. Even though MnO also exhibited an adverse effect on Pt by lowering the number of exposed metal sites, rapid desorption of the linearly adsorbed CO species governed the performance of the Pt/MnO in the RWGS. [ABSTRACT FROM AUTHOR]

Supported metal catalysts are widely used for chemical conversion, in which construction of high density metal‐oxide or oxide‐metal interface is an important means to improve their reaction performance. Here, Cu@ZnOx encapsulation structure has been in situ constructed through gas‐phase migration of Zn species from ZnO particles onto surface of Cu nanoparticles under CO2 hydrogenation atmosphere at 450 °C. The gas‐phase deposition of Zn species onto the Cu surface and growth of ZnOx overlayer is self‐limited under the high temperature and redox gas (CO2/H2) conditions. Accordingly, high density ZnOx‐Cu interface sites can be effectively tailored to have an enhanced activity in CO2 hydrogenation to methanol. This work reveals a new route for the construction of active oxide‐metal interface and classic strong metal‐support interaction state through gas‐phase migration of support species induced by high temperature redox reaction atmosphere. [ABSTRACT FROM AUTHOR]

Organic electrosynthesis has consistently aroused significant interest within both academic and industrial spheres. Despite the considerable progress achieved in this field, the majority of electrochemical transformations have been conducted through the utilization of direct‐current (DC) electricity. In contrast, the application of alternating current (AC), characterized by its polarity‐alternating nature, remains in its infancy within the sphere of organic synthesis, primarily due to the absence of a comprehensive theoretical framework. This minireview offers an overview of recent advancements in AC‐driven organic transformations and seeks to elucidate the differences between DC and AC electrolytic methodologies by probing into their underlying physical principles. These differences encompass the ability of AC to preclude the deposition of metal catalysts, the precision in modulating oxidation and reduction intensities, and the mitigation of mass transfer processes. [ABSTRACT FROM AUTHOR]

The development of oxidation catalysts that are resistant to sulfur poisoning is crucial for extending the lifespan of catalysts in real‐working conditions. Herein, we describe the design and synthesis of oxide‐metal interaction (OMI) catalyst under oxidative atmospheres. By using organic coated TiO2, an oxide/metal inverse catalyst with non‐classical oxygen‐saturated TiO2 overlayers were obtained at relatively low temperature. These catalysts were found to incorporate ultra‐small Pd metal and support particles with exceptional reactivity and stability for CO oxidation (under 21 vol % O2 and 10 vol % H2O). In particular, the core (Pd)‐shell (TiO2) structured OMI catalyst exhibited excellent resistance to SO2 poisoning, yielding robust CO oxidation performance at 120 °C for 240 h (at 100 ppm SO2 and 10 vol % H2O). The stability of this new OMI catalyst was explained through density functional theory (DFT) calculations that interfacial oxygen atoms at Pd−O−Ti sites (of oxygen‐saturated overlayers) serve as non‐metal active sites for low‐temperature CO oxidation, and change the SO2 adsorption from metal(d)‐to‐SO2(π*) back‐bonding to much weaker σ(Ti−S) bonding. [ABSTRACT FROM AUTHOR]

Knowing the structure of catalytically active species/phases and providing methods for their purposeful generation are two prerequisites for the design of catalysts with desired performance. Herein, we introduce a simple method for precise preparation of supported/bulk catalysts. It utilizes the ability of metal oxides to dissolve and to simultaneously precipitate during their treatment in an aqueous ammonia solution. Applying this method for a conventional VOx−Al2O3 catalyst, the concentration of coordinatively unsaturated Al sites was tuned simply by changing the pH value of the solution. These sites affect the strength of V−O−Al bonds of isolated VOx species and thus the reducibility of the latter. This method is also applicable for controlling the reducibility of bulk catalysts as demonstrated for a CeO2−ZrO2−Al2O3 system. The application potential of the developed catalysts was confirmed in the oxidative dehydrogenation of ethylbenzene to styrene with CO2 and in the non‐oxidative propane dehydrogenation to propene. Our approach is extendable to the preparation of any metal oxide catalysts dissolvable in an ammonia solution. [ABSTRACT FROM AUTHOR]

Metal–organic framework‐based materials are promising single‐site catalysts for electrocatalytic nitrate (NO3−) reduction to value‐added ammonia (NH3) on account of well‐defined structures and functional tunability but still lack a molecular‐level understanding for designing the high‐efficient catalysts. Here, we proposed a molecular engineering strategy to enhance electrochemical NO3−‐to‐NH3 conversion by introducing the carbonyl groups into 1,2,4,5‐tetraaminobenzene (BTA) based metal‐organic polymer to precisely modulate the electronic state of metal centers. Due to the electron‐withdrawing properties of the carbonyl group, metal centers can be converted to an electron‐deficient state, fascinating the NO3− adsorption and promoting continuous hydrogenation reactions to produce NH3. Compared to CuBTA with a low NO3−‐to‐NH3 conversion efficiency of 85.1 %, quinone group functionalization endows the resulting copper tetraminobenzoquinone (CuTABQ) distinguished performance with a much higher NH3 FE of 97.7 %. This molecular engineering strategy is also universal, as verified by the improved NO3−‐to‐NH3 conversion performance on different metal centers, including Co and Ni. Furthermore, the assembled rechargeable Zn−NO3− battery based on CuTABQ cathode can deliver a high power density of 12.3 mW cm−2. This work provides advanced insights into the rational design of metal complex catalysts through the molecular‐level regulation for NO3− electroreduction to value‐added NH3. [ABSTRACT FROM AUTHOR]

The direct functionalization of inert C(sp3)‐H bonds to form carbon‐carbon and carbon‐heteroatom bonds offers vast potential for chemical synthesis and therefore receives increasing attention. At present, most successes come from strategies using metal catalysts/reagents or photo/electrochemical processes. The use of organocatalysis for this purpose remains scarce, especially when dealing with challenging C−H bonds such as those from simple alkanes. Here we disclose the first organocatalytic direct functionalization/acylation of inert C(sp3)‐H bonds of completely unfunctionalized alkanes. Our approach involves N‐heterocyclic carbene catalyst‐mediated carbonyl radical intermediate generation and coupling with simple alkanes (through the corresponding alkyl radical intermediates generated via a hydrogen atom transfer process). Unreactive C−H bonds are widely present in fossil fuel feedstocks, commercially important organic polymers, and complex molecules such as natural products. Our present study shall inspire a new avenue for quick functionalization of these molecules under the light‐ and metal‐free catalytic conditions. [ABSTRACT FROM AUTHOR]

Synthesis of formate from hydrogenation of carbon dioxide (CO2) is an atom‐economic reaction but is confronted with challenges in developing high‐performance non‐precious metal catalysts for application of the process. Herein, we report a highly durable edge‐rich molybdenum disulfide (MoS2) catalyst for CO2 hydrogenation to formate at 200 °C, which delivers a high selectivity of over 99 % with a superior turnover frequency of 780.7 h−1 surpassing those of previously reported non‐precious metal catalysts. Multiple experimental characterization techniques combined with theoretical calculations reveal that sulfur vacancies at MoS2 edges are the active sites and the selective production of formate is enabled via a completely new water‐mediated hydrogenation mechanism, in which surface OH* and H* species in dynamic equilibrium with water serve as moderate hydrogenating agents for CO2 with residual O* reduced by hydrogen. This study provides a new route for developing low‐cost high‐performance catalysts for CO2 hydrogenation to formate. [ABSTRACT FROM AUTHOR]

Dual‐atom catalysts (DACs) have been a new frontier in heterogeneous catalysis due to their unique intrinsic properties. The synergy between dual atoms provides flexible active sites, promising to enhance performance and even catalyze more complex reactions. However, precisely regulating active site structure and uncovering dual‐atom metal interaction remain grand challenges. In this review, we clarify the significance of the inter‐metal interaction of DACs based on the understanding of active center structures. Three diatomic configurations are elaborated, including isolated dual single‐atom, N/O‐bridged dual‐atom, and direct dual‐metal bonding interaction. Subsequently, the up‐to‐date progress in heterogeneous oxidation reactions, hydrogenation/dehydrogenation reactions, electrocatalytic reactions, and photocatalytic reactions are summarized. The structure‐activity relationship between DACs and catalytic performance is then discussed at an atomic level. Finally, the challenges and future directions to engineer the structure of DACs are discussed. This review will offer new prospects for the rational design of efficient DACs toward heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The past decade has witnessed the great potential of Fe‐based single‐atom electrocatalysis in catalyzing oxygen reduction reaction (ORR). However, it remains a grand challenge to substantially improve their intrinsic activity and long‐term stability in acidic electrolytes. Herein, we report a facile chemical vapor deposition strategy, by which high‐density Fe atoms (3.97 wt%) are coordinated with square‐planar para‐positioned nitrogen and phosphorus atoms in a hierarchical carbon framework. The as‐crafted atomically dispersed Fe catalyst (denoted Fe‐SA/PNC) manifests an outstanding activity towards ORR over the entire pH range. Specifically, the half‐wave potential of 0.92 V, 0.83 V, and 0.86 V vs. reversible hydrogen electrode (RHE) are attained in alkaline, neutral, and acidic electrolytes, respectively, representing the high performance among reported catalysts to date. Furthermore, after 30,000 durability cycles, the Fe‐SA/PNC remains to be stable with no visible performance decay when tested in 0.1 M KOH and 0.5 M H2SO4, and only a minor negative shift of 40 mV detected in 0.1 M HClO4, significantly outperforming commercial Pt/C counterpart. The coordination motif of Fe‐SA/PNC is validated by density functional theory (DFT) calculations. This work provides atomic‐level insight into improving the activity and stability of non‐noble metal ORR catalysts, opening up an avenue to craft the desired single‐atom electrocatalysts. [ABSTRACT FROM AUTHOR]

Carbonate hydrogenation to formate is a promising route to convert captured carbon dioxide into valuable chemicals, thus reducing carbon emissions and creating a revenue return. Developing inexpensive catalysts with high activity, selectivity, and stability remains challenging. We report a supported non‐noble metal catalyst, Ni/TiO2, with great selectivity over 96 % and excellent stability in catalyzing the conversion of carbonate into formate in aqueous solution. Ni0 and Ni2+ species are both observed in Ni/TiO2 catalysts, and the synergistic effect of these two Ni components leads to high activity and high selectivity of carbonate hydrogenation to formate. [ABSTRACT FROM AUTHOR]

Controlling the structure and properties of catalysts through atomic arrangement is the source of producing a new generation of advanced catalysts. A highly active and stable catalyst in catalytic reactions strongly depends on an ideal arrangement structure of metal atoms. We demonstrated that the introduction of the defect‐rich structures, low coordination number (CN), and tensile strain in three‐dimensional (3D) urchin‐like palladium nanoparticles through chlorine bonded with sp‐C in graphdiyne (Pd‐UNs/Cl‐GDY) can regulate the arrangement of metal atoms in the palladium nanoparticles to form a special structure. In situ Fourier infrared spectroscopy (FTIR) and theoretical calculation results show that Pd‐UNs/Cl‐GDY catalyst is beneficial to the oxidation and removal of CO intermediates. The Pd‐UNs/Cl‐GDY for methanol oxidation reaction (MOR) that display high current density (363.6 mA cm−2) and mass activity (3.6 A mgPd−1), 12.0 and 10.9 times higher than Pd nanoparticles, respectively. The Pd‐UNs/Cl‐GDY catalyst also exhibited robust stability with still retained 95 % activity after 2000 cycles. A defects libraries of the face‐centered cubic and hexagonal close‐packed crystal catalysts (FH‐NPs) were synthesized by introducing chlorine in graphdiyne. Such defect‐rich structures, low CN, and tensile strain tailoring methods have opened up a new way for the catalytic reaction of MOR. [ABSTRACT FROM AUTHOR]

Electrocatalysts for highly efficient oxygen reduction reaction (ORR) are crucial for energy conversion and storage devices. Single‐atom catalysts with maximized metal utilization and altered electronic structure are the most promising alternatives to replace current benchmark precious metals. However, the atomic level understanding of the functional role for each species at the anchoring sites is still unclear and poorly elucidated. Herein, we report Fe single atom catalysts with the sulfur and oxygen functional groups near the atomically dispersed metal centers (Fe1/NSOC) for highly efficient ORR. The Fe1/NSOC delivers a half‐wave potential of 0.92 V vs. RHE, which is much better than those of commercial Pt/C (0.88 V), Fe single atoms on N‐doped carbon (Fe1/NC, 0.89 V) and most reported nonprecious metal catalysts. The spectroscopic measurements reveal that the presence of sulfur group induces the formation of epoxy groups near the FeN4S2 centers, which not only modulate the electronic structure of Fe single atoms but also participate the catalytic process to improve the kinetics. The density functional theory calculations demonstrate the existence of sulfur and epoxy group engineer the charges of Fe reactive center and facilitate the reductive release of OH* (rate‐limiting step), thus boosting the overall oxygen reduction efficiency. [ABSTRACT FROM AUTHOR]

Fundamental understanding of the synergistic effect of bimetallic catalysts is of extreme significance in heterogeneous catalysis, but a great challenge lies in the precise construction of uniform dual‐metal sites. Here, we develop a novel method for constructing Pt1−Fe1/ND dual‐single‐atom catalyst, by anchoring Pt single atoms on Fe1−N4 sites decorating a nanodiamond (ND) surface. Using this catalyst, the synergy of nitroarenes selective hydrogenation is revealed. In detail, hydrogen is activated on the Pt1−Fe1 dual site and the nitro group is strongly adsorbed on the Fe1 site via a vertical configuration for subsequent hydrogenation. Such synergistic effect decreases the activation energy and results in an unprecedented catalytic performance (3.1 s−1 turnover frequency, ca. 100 % selectivity, 24 types of substrates). Our findings advance the applications of dual‐single‐atom catalysts in selective hydrogenations and open up a new way to explore the nature of synergistic catalysis at the atomic level. [ABSTRACT FROM AUTHOR]

The document introduces Charlie Ruffman, a research fellow at the University of Auckland, New Zealand, specializing in catalysis, liquid metals, density functional theory, and ab-initio molecular dynamics. Ruffman's research focuses on understanding the mechanisms underlying selective CO2 reduction on liquid metal catalysts, highlighting the impact of dynamic motion of atoms during catalysis. Ruffman's favorite quote is "All models are wrong, but some are useful," emphasizing the importance of dedicated time and focus for progress in scientific endeavors. More information about Ruffman's work and publications can be found in his profile on the University of Auckland's website. [Extracted from the article]

Transition metal‐catalyzed C−S cross‐coupling has emerged as an important strategy to furnish thioethers; however, the dominant utilization of noble metal catalysts as well as the construction of challenging C(sp3)−S bonds by transition metal‐catalysis remain highly problematic. Earth‐abundant manganese has gathered increasing interest as an attractive catalyst for new reaction development; nevertheless, C(sp3)−S cross‐coupling reaction by manganese catalysis has not been reported. Herein, we disclose a highly efficient manganese‐catalyzed redox‐neutral thiolation of a broad range of alkyl halides with thioformates as practical sulfuration agents. Strategically, employing easily synthesized thioformates as thiyl radical precursors allows access to various aryl and alkyl thioethers in good to excellent yields. Notably, this redox‐neutral method avoids the utilization of strong bases, external ligands, forcing reaction conditions, and stoichiometric manganese, thus presenting apparent advantages, such as broad substrate scope, excellent functional group compatibility, and mild reaction conditions. Finally, the utilities of this method are also illustrated by downstream transformations and late‐stage thiolation of structurally complex natural products and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Benzothiophenes, activated by oxidation to the corresponding S‐oxides, undergo C−H/C−H‐type coupling with phenols to give C4 arylation products. While an electron‐withdrawing group at C3 of the benzothiophene is important, the process operates without a directing group and a metal catalyst, thus rendering it compatible with sensitive functionalities—e.g. halides and formyl groups. Quantum chemical calculations suggest a formal stepwise mechanism involving heterolytic cleavage of an aryloxysulfur species to give a π‐complex of the corresponding benzothiophene and a phenoxonium cation. Subsequent addition of the phenoxonium cation to the C4 position of the benzothiophene is favored over the addition to C3; Fukui functions predict that the major regioisomer is formed at the more electron‐rich position between C3 and C4. Varied selective manipulation of the benzothiophene products showcase the synthetic utility of the metal‐free arylation process. [ABSTRACT FROM AUTHOR]

Platinum nanoparticles (NPs) supported by titania exhibit a strong metal‐support interaction (SMSI)[1] that can induce overlayer formation and encapsulation of the NP's with a thin layer of support material. This encapsulation modifies the catalyst's properties, such as increasing its chemoselectivity[2] and stabilizing it against sintering.[3] Encapsulation is typically induced during high‐temperature reductive activation and can be reversed through oxidative treatments.[1] However, recent findings indicate that the overlayer can be stable in oxygen.[4, 5] Using in situ transmission electron microscopy, we investigated how the overlayer changes with varying conditions. We found that exposure to oxygen below 400 °C caused disorder and removal of the overlayer upon subsequent hydrogen treatment. In contrast, elevating the temperature to 900 °C while maintaining the oxygen atmosphere preserved the overlayer, preventing platinum evaporation when exposed to oxygen. Our findings demonstrate how different treatments can influence the stability of nanoparticles with or without titania overlayers. expanding the concept of SMSI and enabling noble metal catalysts to operate in harsh environments without evaporation associated losses during burn‐off cycling. [ABSTRACT FROM AUTHOR]

Chemically recyclable polymers that can depolymerize into their constituent monomers are attractive candidates to replace non‐recyclable petroleum‐derived plastics. However, the physical properties and mechanical strengths of depolymerizable polymers are commonly insufficient for practical applications. Here we demonstrate that by proper ligand design and modification, aluminum complexes can catalyse stereoretentive ring‐opening polymerization of dithiolactone, yielding highly isotactic polythioesters with molar masses up to 45.5 kDa. This material can form crystalline stereocomplex with a Tm of 94.5 °C, and exhibits mechanical performances comparable to petroleum‐based low density polyethylene. Exposure of the polythioester to aluminum precatalyst used to synthesized it resulted in depolymerization to pristine chiral dithiolactone. Experimental and computational studies suggest that aluminum complexes have appropriate binding affinity with sulfide propagating species, thereby avoiding catalyst poisoning and minimizing epimerization reactions, which has not been accessible using other metal catalysts. Overall, aluminum catalysis provides access to performance‐advantaged stereoregular recyclable plastics as a promising alternative to petrochemical plastics, thus incentivizing improved plastic sustainability. [ABSTRACT FROM AUTHOR]

In supported metal catalysts, the supports would strongly interact with the metal components instead of just acting as a carrier, which greatly affects both of their synthesis and catalytic activity, selectivity, and stability. Carbon is considered as very important but inert support and thus hard to induce strong metal‐support interaction (SMSI). This mini‐review highlights that sulfur—a documented poison reagent for metal catalysts—when doped in a carbon supports can induce diverse SMSI phenomenon, including electronic metal‐support interaction (EMSI), classic SMSI, and reactive metal‐support interaction (RMSI). These SMSI between metal and sulfur‐doped carbon (S−C) supports enables the catalysts with extraordinary resistance to sintering at high temperatures of up to 1100 °C, which allows the general synthesis of single‐atom, alloy cluster, and intermetallic compound catalysts with high dispersion and metal loading for a variety of applications. [ABSTRACT FROM AUTHOR]