Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

Morphological engineering of monodispersed Co2P nanocrystals for efficient alkaline water and seawater splitting

Developing feasible synthetic strategies for preparing advanced nanomaterials with narrow size distributions and well-defined structures represents a cutting-edge field in alkaline water and seawater electrolysis. Herein, the monodispersed Co2P nanocrystals with tunable morphologies, namely one-dimensional nanorods (Co2P-R), nanoparticles (Co2P-P), and nanospheres (Co2P-S), were controllably synthesized by using a Schlenk system through optimizing the reactivity of cobalt- and phosphorus-based sources. The resulting Co2P-R exhibited superior electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH, simulated seawater, and natural seawater. Impressively, the reconstructed active species effectively avoid the chlorine evolution on Co2P-R surface and facilitate OER process. Density functional theory (DFT) calculations revealed that Co2P-R exhibited an optimal d-band center (εd) and a lower energy barrier for the rate-determining steps in both HER and OER processes in comparison with Co2P-P and Co2P-S. Additionally, the Co2P-R showed a more favorable water adsorption energy (EH2O) over Cl- adsorption energy (ECl-), which contributes to its enhanced seawater electrolysis performance. The Co2P-R||Co2P-R electrolyzer achieves a low voltage of 1.70, 1.76, and 1.76 V at 100 mA cm-2 in alkaline freshwater, simulated seawater, and natural seawater, respectively, and demonstrates stable operation for 200 h at 100 mA cm-2.

Recent progress in the electrocatalytic applications of thiolate-protected metal nanoclusters

Ultrasmall metal nanoclusters (NCs) with atomic precision possess a size range between individual atoms and plasmonic nanomaterials. These atomically precise materials represent an emerging class of nanocatalysts, offering unique opportunities to explore electrocatalytic properties and establish precise structure-property correlations at the atomic scale. Among the large number of metal NCs that are stabilized by various ligands, thiolate-protected metal NCs are a particularly prominent class for electrocatalytic investigations. Recent experimental and theoretical studies have demonstrated the significant potential of these materials in enhancing various electrocatalytic reactions, including hydrogen evolution, oxygen reduction and CO2 reduction reactions. However, comprehensive and in-depth discussions regarding their catalytic properties, particularly from a theoretical standpoint, are limited and require further explorations. In this review, we focus on the recent progress in thiolate-protected metal NCs in the field of electrocatalysis. The influences of structure, ligand, doping and interface control on their electrocatalytic activity/selectivity and the reaction mechanisms are discussed. Importantly, the perspectives we propose regarding future research endeavors are expected to offer valuable references for subsequent investigations in this area.

Building lactams by highly selective hydrodeoxygenation of cyclic imides using an alumina-supported AgRe bimetallic nanocatalyst

The rational design of robust nanocatalysts containing the suitable active sites for building relevant organic compounds, such as lactams, is a desired approximation towards the development of a sustainable fine chemistry field. In that sense, the design of a proper nanomaterial able to mediate the selective hydrodeoxygenation of cyclic imides to lactams with high tolerance to the preservation of aromatic rings remains rather unexplored. Here, we show the design of a bimetallic AgRe nanomaterial with notable activity and selectivity to mediate this transformation affording more than 60 lactams from the corresponding imides. Interestingly, in this work we disclose that the optimal AgRe nanocatalyst is constituted by AgReO4 nanoaggregates that undergo an in situ hydrogenative dispersion to form the active centers composed by Ag0 nanoparticles and ReOx species. Deep characterization, together with kinetic and mechanistic studies, have revealed that the intimate Ag-Re contact intrinsic to AgReO4 species is key for the formation of the most active catalytic sites and the proper bimetallic cooperation required for mediating the desired process.

On the Hunt for Chiral Single-Atom Catalysts

Enantioselective transformations are crucial in various fields, including chemistry, biology, and materials science. Today, the selective production of enantiopure compounds is achieved through asymmetric homogeneous catalysis. Single-atom catalysts (SACs) are emerging as a transformative approach in chemistry, enabling the heterogenization of organometallic complexes and effectively bridging the gap between homogeneous and heterogeneous catalysis. Despite their potential, the integration of SACs into enantioselective processes remains an underexplored area. This perspective offers a comprehensive analysis of possible strategies for the design of heterogeneous asymmetric catalysts, examining how chiral surfaces, chiral modifiers, grafted chiral complexes, and spatial confinement techniques can be effectively employed to enhance enantioselectivity. Each of these methods presents distinct advantages and challenges; for example, chiral surfaces and chiral modifiers offer potential for tailored reactivity but can suffer from limited stability and selectivity, while grafted chiral complexes provide robust platforms but may face issues related to scalability and synthesis complexity. Spatial confinement strategies show promise in enhancing catalyst efficiency but may be constrained by accessibility and reproducibility concerns. These strategies lay the groundwork for their adaptation to SACs, by providing innovative approaches to replicate the well-defined chiral environments of homogeneous catalysts while preserving the stability, reusability, and unique advantages of single-atom heterogeneous systems.

The Cooperative Effects of the Rh-M Dual-Metal Atomic Pairs in Formic Acid Oxidation

The continuously increasing mass activity of precious metal in formic acid oxidation reaction (FAOR) is the key to achieving the practical application of direct formic acid fuel cells (DFAFCs). Herein, Rh-based dual-metal atomic pairs supported on nitrogen-doped carbon catalysts [DAP-(M, Rh)/CN] with adjacent interatomic Rh-M (M = V, Cr, Mn, Fe, Co, Ni, Cu) have been synthesized by a "host-guest" strategy. It is discovered that DAP-(Cr, Rh)/CN shows the highest mass activity of 64.1 A mg-1, which is 3.8 times higher than that of the single atom Rh catalyst (17.0 A mg-1) and two orders of magnitude higher than Pd/C (0.58 A mg-1). Interestingly, the mass activity of DAP-(M, Rh)/CN first increases from 11.7 A mg-1 (Rh-V) to 64.1 A mg-1 (Rh-Cr) and then decreases to 21.8 A mg-1 (Rh-Cu), forming a volcano curve of the reaction activity. Density functional theory calculations combined with in situ Fourier transform infrared spectrometer (FTIR) spectra reveal that formic acid oxidized on a series of DAP-(M, Rh)/CN catalysts through the formate route with the subsidiary M metal atoms binding the HCOO species and the Rh atom accepting the H atoms. The most suitable adsorption strength of HCOO on the Cr sites luckily contributes to two spontaneous elementary steps and thus accelerates the FAOR rates.

Aqueous Dehydrogenation of Methyl Formate Catalyzed by a Recyclable Polymer-Grafted Manganese(I) Pincer Complex

Liquid organic hydrogen carriers (LOHCs) are an effective solution for the long-term storage of hydrogen and its long-distance transportation, but one that requires efficient catalysis for hydrogen uptake and release. Homogeneous molecular catalysts employed in LOHC systems usually exhibit high reactivity and selectivity but are difficult to recover and reuse, a fact that severely limits their practical application. Herein, we report an easily synthesized polymer-grafted pincer-type complex of earth-abundant manganese, which can catalyze the aqueous dehydrogenation of methyl formate, an emerging LOHC material. Importantly, this immobilized Mn-pincer catalyst retains the high reactivity of the corresponding molecular catalyst, yet is also recyclable, exhibiting high stability and achieving a total hydrogen-based turnover number of more than 230000 after 5 consecutive recycling rounds.

Recent developments in polymer chemistry, medicinal chemistry and electro-optics using Ni and Pd-based catalytic systems

Catalysis is the fastest and continuously growing field in chemistry. A key component of this process is catalytic systems, which result in increased reaction rates and yields, as well as the ability to tailor the properties of products to the final application. With the development of catalysis, the requirements for catalysts used in these processes have also grown rapidly. Modern catalytic materials should overcome the challenges posed by the modern world of chemistry. They should be durable, and stable, have good catalytic properties, and allow catalytic processes to be carried out under mild and environmentally friendly conditions. In this article, we provide an overview of recent reports on the use of catalytic systems based on nickel and palladium ions in catalytic reactions, leading to functional materials used in the fields of medicinal chemistry, polymer chemistry and electro-optical materials chemistry. Research on the optimization and modification of existing synthetic methods, reports on the synthesis of new functional materials, and articles on new, more efficient catalytic systems that overcome the drawbacks of existing catalysts are described. The presented article reviews current knowledge, providing the newest information from the world of catalysis and synthesis of advanced functional materials, presenting potential directions for further development in these fields.

The presence and absence effect of the template on optical nonlinearity responses of magnetic moleculary imprinted polymer

A magnetic moleculary imprinted polymer (MMIP) was prepared by polymerization reaction of 4-vinylpyridine, magnetic vinylsilane, and crosslinker agent ethylene glycol dimethacrylate in the presence of octahydroquinazolinone target molecule entitled the "template" which had the selective capability of bonding and rebinding. The effects of the presence and absence of template on third-order nonlinear optical responses (NLO) of MMIP at 532 nm were investigated by the application of the Z-scan technique. All samples had the negative reflective index with self-defocusing effect in the order of 10- 8 cm2/W, and the absorption coefficient in the order of 10- 4 cm/W. Moreover, all samples had a valley in the nonlinear absorption coefficient that shows the two-photon absorption (TPA) effect as a dominant phenomenon. The NLO properties of samples were improved by increasing the incident power of laser. Furthermore, the third-order susceptibility, χ(3), and figure of merit (FOM) of samples were calculated. The polarity, charge transferring and porosity in MMIP are the most important factors for having more nonlinearity responses in comparison with other samples. In addition, the MMIP was investigated using SEM/EDX and TEM measurements to check the quality and homogeneity of them, which was essential in photonic device production.

Benzothiazolines Acting as Carbanion and Radical Transfer Reagents in Carbon-Carbon Bond Construction

Traditionally employed as hydrogenation reagents, benzothiazolines have emerged as versatile carbanion and radical transfer reagents, playing a vital role in the construction of various carbon-carbon bonds. The cutting-edge progress in photochemistry and radical chemistry have prompted the study of visible light-driven radical reactions, bringing benzothiazolines into a vibrant focus. Their chemical processes have been uncovered to encompass a variety of activation mechanisms, with five distinct modes having been identified. This work reviews the innovative applications of benzothiazolines as donors of alkyl or acyl groups, achieving hydroalkylation or hydroacylation and alkyl or acyl substitution. By examining their diverse activation mechanisms, this review highlights the potential of benzothiazolines serving as alkyl and acyl groups for further research and development. Moreover, this review will offer exemplary applications and inspiration to synthetic chemists, contributing to the ongoing evolution of benzothiazolines utility in organic synthesis.

Surface engineering of Pt nanocatalysts with transition metal oleates for selective catalysis: a case study on the hydrogenation of α,β-unsaturated aldehydes

Selective and active catalysts enable effective use of feedstocks, reduced energy consumption and waste generation. Tuning the electronic structure of heterogeneous metal nanocatalysts via their surface modifications is a promising strategy to design highly selective and active catalysts for the synthesis of harder to make and more cost-efficient products. We introduce transition metal oleates as a new class of ligands to engineer the catalytically active and very selective surface in organic solvents. Using citral hydrogenation and 5 nm Pt NPs as a model reaction and model catalytic system, respectively, we show that surface engineering of Pt nanocatalysts with metal oleates allows synthesis of desired partially hydrogenated product (geraniol) with ∼90% conversion with selectivity over 93%. We demonstrate that the selective synthesis of the unsaturated alcohols catalyzed by Pt NPs modified by adsorption of the transition metal salts cannot be explained by the widely accepted mechanism of preferred coordination of CO groups by Lewis acids (e.g. partially oxidized transition surface metals). Our results indicate that CO groups prefer to bind to negatively charged surfaces. We propose the explanation on how the adsorption of transition metal oleates can result in the increased electron density at the surface of Pt nanoparticles. Our study not only provides reliable solutions to selective hydrogenation but opens a new possibility of using metal oleates for the electronic ligand effect.

General aggregation-induced deposition approach for creating asymmetric single-atom catalysts

We introduce a general aggregation-induced deposition approach for synthesizing high-density Co single atom sites with precise atomic configuration on an N,O co-doped hollow carbon matrix (Co-SAs/NHC). Moreover, this strategy can also be applied to fabricate ten different metal single-atom catalysts. This design leverages the interactions between Co sites across adjacent carbon layers, enhancing the structural and chemical durability and the catalytic performance of the Co-SAs/NHC-based zinc-air battery.

Towards Surface-Enhanced Homogeneous Catalysis: Tailoring the Enrichment of Metal Complexes at Ionic Liquid Surfaces

When talking about homogeneous catalyst systems, it has long been assumed that the system at hand consists of a transition metal complex in solution with the liquid interface representing the composition of the bulk solution. Now, in light of considerable developments in the study of metal complexes dissolved in ionic liquids with their negligible vapor pressures, more detailed studies of the composition at the liquid/gas interface became possible. These investigations revealed pronounced surface enrichment and segregation effects of high relevance for practical applications. This article reviews recent advancements in tailoring the interfacial composition of ionic liquid-based catalytic systems. A particular focus is dedicated to surface enrichment phenomena, and a variety of parameters are presented for deliberate control of the local concentration of the complexes at the surface, that is, the nature of the ligands, the bulk concentration, the temperature, and the nature of the IL solvent. As experimental methods, angle-resolved X-ray photoelectron spectroscopy (ARXPS) and vacuum-based pendant-drop surface tension measurements were applied. The reviewed results are intended to provide the basis for the advancement of catalytic systems with high surface areas, such as in supported ionic liquid phase (SILP) catalysis, where the interface design is directly interconnected with catalytic performance.

Exploiting Photoinduced Atom Transfer Radical Polymerizations with Boron-Dopant and Nitrogen-Defect Synergy in Carbon Nitride Nanosheets

Graphitic carbon nitrides (g-C3N4) possess various benefits as heterogeneous photocatalysts, including tunable bandgaps, scalability, and chemical robustness. However, their efficacy and ongoing advancement are hindered by challenges like limited charge-carrier separation rates, insufficient driving force for photocatalysis, small specific surface area, and inadequate absorption of visible light. In this study, boron dopants and nitrogen defects synergy are introduced into bulk g-C3N4 through the calcination of a blend of nitrogen-defective g-C3N4 and NaBH4 under inert conditions, resulting in the formation of BCN nanosheets characterized by abundant porosity and increased specific surface area. These BCN nanosheets promote intermolecular single electron transfer to the radical initiator, maintaining radical intermediates at a low concentration for better control of photoinduced atom transfer radical polymerization (photo-ATRP). Consequently, this method yields polymers with low dispersity and tailorable molecular weights under mild blue light illumination, outperforming previous reports on bulk g-C3N4. The heterogeneity of BCN enables easy separation and efficient reuse in subsequent polymerization processes. This study effectively showcases a simple method to alter the electronic and band structures of g-C3N4 with simultaneously introducing dopants and defects, leading to high-performance photo-ATRP and providing valuable insights for designing efficient photocatalytic systems for solar energy harvesting.

Two-Phase Epoxidations with Micellar Catalysts: Insights, Limitations, and Perspectives

Biphasic molecular catalysis is a promising strategy for combining catalyst recycling with the synthesis of advanced chemical products. The anchoring of catalysts to surfactants in water allows for both catalyst solubility in aqueous media and a simple separation from the organic product. In biphasic epoxidations, this approach allows the use of environmentally benign hydrogen peroxide as oxidant. However, challenges remain due to mass transport limitations between the aqueous and organic phase, incompatibilities in the multicomponent system, and side reactions in the acidic medium. Hence, the development of surface-active catalysts that enable controlled phase separation from all other components is highlighted in this concept article.

Two-step tandem electrochemical conversion of oxalic acid and nitrate to glycine

This study presents a facile tandem strategy for improving the efficiency of glycine electrosynthesis from oxalic acid and nitrate. In this tandem electrocatalytic process, oxalic acid is first reduced to glyoxylic acid, while nitrate is reduced to hydroxylamine. Subsequent coupling of these two precursors results in the formation of a C-N bond, producing the intermediate glyoxylic acid oxime, which is further reduced in situ to glycine. Here we show, using only a simple Pb foil electrode, which maximizes the yield of the first step of the transformation (i.e. the reduction of oxalic acid to glyoxylic acid) prior to the coupling step allows for an unprecedented selectivity and conversion for glycine electrosynthesis to be achieved. Overall, a maximum glycine faradaic efficiency (FE) of 59% is achieved at -300 mA cm-2 and a high glycine partial current density of -232 mA cm-2 and a glycine production rate of 0.82 mmol h-1 cm-2 are attained at -400 mA cm-2, thereby paving the way for an energy and economically efficient electrochemical synthesis of glycine.

Electron-Coupling Effect Modulating the d-Band Center of Asymmetric Cobalt Single-Atom Sites for Electrocatalytic Oxygen Reduction

We introduce an aggregation-induced deposition approach for rapidly synthesizing asymmetric Co-N3O single-atom sites (SAs) with a precise atomic configuration on a hollow carbon matrix (Co-SAs/NHC). This design leverages the electron-coupling effect between Co SAs across adjacent carbon layers, enhancing the intrinsic activity and durability of the catalyst. In the ORR, the Co-SAs/NHC catalyst displayed a half-wave potential improvement of 51 mV, achieving a mass activity 5-fold that of commercial Pt/C. Remarkably, after 30 000 potential cycles, there was a negligible half-wave potential loss of just 17 mV. Density functional theory calculations revealed that the adjacent Co-N3O sites optimized the electronic structure and d-band center of the Co atom, thereby reducing the adsorption energy of the OH* intermediates. This work offers a pathway for developing industrial-grade single-atom catalysts (SACs) with satisfactory catalytic activity and durability.

Ligand Influence on the Performance of Cesium Lead Bromide Perovskite Quantum Dots in Photocatalytic C(sp3)-H Bromination Reactions

Lead halide perovskite quantum dots (LHP QDs) CsPbX3 generate immense interest as narrow-band emitters for displays, lasers, and quantum light sources. All QD applications rely on suited engineering of surface capping ligands. The first generation of LHP QDs employed oleic acid/oleyl amine capping and have found only a limited use in photoredox catalysis. These catalysts have been reported to be unstable and decompose over the course of the reaction, thus reducing turnover numbers (TONs) and limiting their synthetic ability. Herein, the impact of eight distinct surface ligands on monodisperse CsPbBr3 QDs is reported, affording a thorough comprehension of their performance in photocatalytic C-H brominations. These efforts yielded QDs operating at extremely low catalyst loadings (<100 ppb) with TONs over 9,000,000 per LHP QD. We emphasize that the optimal catalytic performance requires increased QD surface accessibility without compromising the QD structural and colloidal integrity. Control experiments indicated that well-known photoredox catalysts such as Ir(ppy)3, Ru(bpy)3Cl2, or 4CzlPN are ineffective in the same reaction. Mechanistic studies reveal that the C-Br bond reduction in CH2Br2 is the rate-limiting step and is likely facilitated through interaction with the CsPbBr3 QD surface. This work outlines a holistic approach toward the design of practically useful photocatalysts out of QDs comprising structurally soft QD cores and dynamically bound capping ligands.

Natural Biogenic Templates for Nanomaterial Synthesis: Advances, Applications, and Environmental Perspectives

This review explores the use of biogenic templates in nanomaterial synthesis, emphasizing their role in promoting environmentally sustainable nanotechnology. It categorizes various biogenic templates, including agricultural byproducts and microorganisms, stating their suitability for forming nanostructures due to their distinct properties. A comparative analysis of monostep and multistep synthesis methods is provided, focusing on their efficiencies and outcomes when using biogenic templates. Further, this review also highlights how these templates can generate complex nanostructures and hybrid materials with enhanced functionalities. Applications of biogenic templates across biomedicine, biotechnology, environmental science, and energy are discussed along with their utilization scope in agriculture and electronics. Benefits from nanostructures from biotemplates include sustainability, low cost, and reduced toxicity, but challenges like scalability, reproducibility, and regulatory compliance persist. Future research focuses on improving synthesis techniques, discovering new templates, and evaluating environmental and cytotoxic impacts, especially for biomedical uses. In conclusion, the review reaffirms the potential of biogenic templates in sustainable nanomaterial synthesis while highlighting the ongoing challenges that need to be addressed for broader adoption.

Sustainable Formate Production via Highly Active CO2 Hydrogenation Using Porous Organometallic Polymer with Ru-PNP Active Sites

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO2) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kgformate/(kgcatalyst ⋅ d). Furthermore, the facile separation characteristics and recyclability of the heterogeneous catalysts were confirmed.

Superhydrophilic S-NiFe LDH by Room Temperature Synthesis for Enhanced Alkaline Water/Seawater Oxidation at Large Current Densities

Developing high-performance oxygen evolution reaction (OER) electrocatalysts that can operate stably at large current densities in seawater plays a crucial role in enabling large-scale hydrogen production, however, it remains a significant challenge. Herein, sulfur-doped NiFe layered double hydroxide nanosheet (S-NiFe LDH) grown on a 3D porous nickel foam skeleton is synthesized through electrochemical deposition and ion-exchange strategies at room temperature as high-performance, highly selective, and durable OER electrocatalyst for seawater electrolysis at large current density. The incorporation of S can enhance the conductivity, promote structural reconstruction to form highly active oxyhydroxides, as well as improve the anti-corrosion ability of chloride ions. Furthermore, due to its unique self-supporting structure and superhydrophilicity, which provide abundant active sites and promote efficient bubble release, the optimized electrocatalyst demands a minimal overpotential of 278 and 299 mV to generate 1000 mA cm-2 in alkaline freshwater/seawater, respectively, confirming its excellent OER activity. Meanwhile, the synthesized electrocatalyst also demonstrates exceptional stability in both media, as it maintains stable performance for a duration of 200 h at 500 mA cm-2. The present work offers an efficient strategy and innovative viewpoint for developing efficient OER electrocatalysts for seawater electrolysis.

Recent trends in production and potential applications of microbial amylases: A comprehensive review

α-amylases are vital biocatalysts that constitute a billion-dollar industry with a substantial and enduring global demand. Amylases hydrolyze the α-1,4-glycosidic linkages in starch polymers to generate maltose and malto-oligosaccharides subunits. Amylases are key enzymes that have promising applications in various industrial processes ranging from pharmaceutical, pulp and paper, textile food industries to bioremediation and biofuel sectors. Microbial enzymes have been widely used in industrial applications owing to their ease of availability, cost-effectiveness and better stability at extreme temperatures and pH. α-amylases derived from distinct microbial origins exhibit diverse characteristics, which make them suitable for specific applications. The routine application of immobilized enzymes has become a standard practice in the production of numerous industrial products across the pharmaceutical, chemical, and food industries. This review details the structural makeup of microbial α-amylase to understand its thermodynamic characteristics, aiming to identify key areas that could be targeted for improving the thermostability, pH tolerance and catalytic activity of α-amylase through various immobilization techniques or specific enzyme engineering methods. Additionally, the review briefly explores the enzyme production strategies, potential sources of α-amylases, and use of cost-effective and sustainable raw materials for enzyme production to obtain α-amylases with unconventional applications in various industrial sectors. Major hurdles, challenges and future prospects involving microbial α-amylases has been briefly discussed by considering its diverse applications in industrial bioprocessing.

Surface Involvement in the Boosting of Chiral Organocatalysts for Efficient Asymmetric Catalysis

Nanostructures with curved surfaces and chiral-directing residues are highly desirable in the synthesis of asymmetric chemicals, but they remain challenging to synthesize without using unique templates due to the disfavored torsion energy of twisted architectures toward chiral centers. Here, a strategy for the facile fabrication of highly cured capsule-shaped catalysts with chiral interiors by the amplification of molecular chirality via the irreversible cross-linking of 2D asymmetric laminates is presented. The key to the success of these irregular 2D layers is the use of hierarchical assembly of chiral macrocycles, which can exactly regulate the cured nanostructures as well as asymmetric catalysis. The cross-linking of 2D laminates from the assembly of hexameric macrocycles with one proline edge gave rise to rarely curled capsules with a diameter of 200-400 nm and excellent enantioselectivities as well as diastereoselectivities for asymmetric aldol reactions (94% ee and 1:13 dr). The tetrameric macrocycles decorated with the chiral block produced further curled porous structures, giving an outstanding enantioselectivities (up to 98% ee and 1:17 dr). The strategy of mechanical surface folding will provide a new insight related to increasing the enantioselectivity of chiral organocatalysts.

Design and engineering of microenvironments of supported catalysts toward more efficient chemical synthesis

Catalytic species such as molecular catalysts and metal catalysts are commonly attached to varieties of supports to simplify their separation and recovery and accommodate various reaction conditions. The physicochemical microenvironments surrounding catalytic species play an important role in catalytic performance, and the rational design and engineering of microenvironments can achieve more efficient chemical synthesis, leading to greener and more sustainable catalysis. In this review, we highlight recent works addressing the topic of the design and engineering of microenvironments of supported catalysts, including supported molecular catalysts and supported metal catalysts. Six types of materials, including oxide nano/microparticle, mesoporous silica nanoparticle (MSN), polymer nanomaterial, reticular material, zeolite, and carbon-based nanomaterial, are widely used as supports for the immobilization of catalytic species. We summarize and discuss the synthesis and modification of supports and the positive effects of microenvironments on catalytic properties such as metal-support interaction, molecular recognition, pseudo-solvent effect, regulating mass transfer, steric effect, etc. These design principles and engineering strategies allow access to a better understanding of structure-property relationships and advance the development of more efficient catalytic processes.

Optimizing selectivity via steering dominant reaction mechanisms in steam reforming of methanol for hydrogen production

Enhancing selectivity towards specific products remains a pivotal challenge in energy catalysis. Herein, we present a strategy to refine selectivity via pathway optimization, exemplified by the rational design of catalysts for methanol steam reforming. Over traditional Pd/ZnO catalysts, the direct decomposition of key intermediates CH2O* into CO and H2 on PdZn alloys competes with the oxidation of CH2O* to CO2, leading to inferior selectivity in product distribution. To address this challenge, Cu is introduced to modify the catalytic dynamics, lowering the dissociation energy barrier of water to provide more active hydroxyl groups for the oxidation of CH2O*. Simultaneously, the CO desorption energy barrier on PdCu alloys is elevated, thereby hindering CH2O* decomposition. This dual functionality enhances both the selectivity and activity of the methanol steam reforming reaction. By modulating the activation patterns of key intermediate species, this approach provides new insights into catalyst design for improved reaction selectivity.

Chemical CO2 fixation by a heterogenised Zn(ii)-hydrazone complex

A new Zn(ii) coordination compound, [Zn(HL)(OAc)2] (1), with ONN-donor hydrazone ligand (HL = (E)-4-amino-N'-(1-(pyridin-2-yl)ethylidene)benzohydrazide) was synthesized and structurally characterized by using spectroscopic techniques and X-ray analysis. These analyses indicated that the Zn(ii) ion in the resulting coordination compound is five coordinated and the compound has a free amine functionality on the phenyl ring. Thus, [Zn(HL)(OAc)2] (1) was immobilized on the surface of propionylchloride functionalized silica gel through an amidification process via the reaction of the aniline part of compound 1 and the acyl chloride group of the support. The synthesized heterogeneous catalyst, Si-[Zn(HL)(OAc)2], was characterized by several analytical methods and the results confirmed the successful support of 1 on the surface of the support. Si-[Zn(HL)(OAc)2] was used in a chemical CO2 fixation reaction and styrene epoxide was used as a model substrate to investigate the catalytic performance of the supported Zn(ii) catalyst. Si-[Zn(HL)(OAc)2] can efficiently catalyze the formation of cyclic carbonate from the reaction of epoxide and CO2 in the presence of TBAB as a co-catalyst.

Small Ligand-Involved Pickering Droplet Interface Controls Reaction Selectivity of Metal Catalysts

Developing efficient methods to improve catalytic selectivity, particularly without sacrificing catalytic activity, is of paramount significance for chemical synthesis. In this work, we report a small ligand-involved Pickering droplet interface as a brand-new strategy to effectively regulate reaction selectivity of metal catalysts. It was found that small ligands such as polar arenes could engineer the surface structure of Pt catalysts that were assembled at Pickering droplet interfaces. Due to the strong hydrogen-bonding interactions with water, the polar arenes preferentially adsorbed with the water adlayer that covered Pt surfaces, forming water-mediated metal-organic interfaces on the Pickering emulsion droplets. Such an interface system displayed a significantly enhanced p-vinylaniline selectivity from 8.7 to 94.2% with an unreduced conversion in p-nitrostyrene hydrogenation. The selectivity was found to follow a negatively linear correlation with the bond length of the interfacial hydrogen bonds. Theoretical calculations revealed that the small arene ligands could closely array at the interface, which modulated the adsorption patterns of reactant/product molecules to prevent the C═C group from approaching Pt surfaces without suppressing their accessibility toward reactant molecules. Such a remarkable interfacial steric effect contributed to the efficient control of the hydrogenation selectivity. Our work provides an innovative strategy to modulate the surface structure of metal catalysts, opening a new venue to tune catalytic selectivity.

Ligand-Shell Cooperativity in a Bilayer Silica-Sandwiched Mixed-Metals Nanocatalyst Design for Absolute Selectivity Switch

Unlike homogeneous metal complexes, achieving absolute control over reaction selectivity in heterogeneous catalysts remains a formidable challenge due to the unguided molecular adsorption/desorption on metal-surface sites. Conventional organic surface modifiers or ligands and rigid inorganic and metal-organic porous shells are not fully effective. Here, we introduce the concept of "ligand-porous shell cooperativity" to desirably switch reaction selectivity in heterogeneous catalysis. We present a nanocatalyst design strategy consisting of bilayer silica-sandwiched 2D mixed metal islands. The intimate 2D/2D nanoscale interfacing between porous silica layers and flat island-like mixed-metal sites, combined with organic ligands, creates a nanoconfined microenvironment that enables reliable control of molecular orientation-dependent reactivity, affording the desired product in 100% selectivity. This design simultaneously leverages the hydrophobicity and flexibility of organic ligands and the nanoscale geometric rigidity of the pores inside the inorganic silica shell. Our strategy is effective with simple amorphous silica, random Cu-alloy, and commonly used metal-coordinating ligands. We demonstrate the applicability in industrially significant reactions: selective hydrogenation of alkynes, α,β-unsaturated esters/aldehydes, and nitroarenes. Our findings offer the valuable scope of a multicomponent compact nanoscale design strategy in next-generation switchable, sustainable, and recyclable catalysis.

Role of Metal Cocatalysts in the Photocatalytic Production of Hydrogen from Water Revisited

The use of photocatalysts to promote the production of molecular hydrogen from water, following the so-called water splitting reaction, continues to be a promising route for the green production of fuels. The molecular basis of this photocatalysis is the photoexcitation of electrons from the valence band of semiconductors to their conduction band, from which they can be transferred to chemical reactants, protons in the case of water, to promote a reduction reaction. The mechanism by which such a process takes place has been studied extensively using titanium oxide, a simple material that fulfills most requirements for water splitting. However, photocatalysis with TiO2 tends to be highly inefficient; a cocatalyst, commonly a late transition metal (Au, Pt) in nanoparticle form, needs to be added to facilitate the production of H2. The metal is widely believed to help with the scavenging of the excited electrons from the conduction band of the semiconductor in order to prevent their recombination with the accompanying hole formed in the valence band, a step that cancels the initial photon absorption and competes with the photolytic chemical reduction. Here we review and analyze the molecular basis for that mechanism and argue for an alternative explanation, that the role of the metal is to help with the recombination of the atomic hydrogen atoms produced by proton reduction on the semiconductor surface instead. First, we summarize what is known about the electronic structure of these photocatalysts and how the electronic levels need to line up for the reduction of protons in water to be feasible. Next, we review the current understanding of the dynamics of the steps associated with the absorption of photons, the de-excitation via electron-hole pair recombination and fluorescence decay, and the electronic transitions that lead to proton reduction, and contrast those with the rates of the chemical steps required to produce molecular hydrogen. The following section addresses the changes introduced by the addition of the metal cocatalyst, comparatively evaluating its role as either an electron scavenger or a promoter of the recombination of hydrogen atoms. A discussion of the viable chemical mechanisms for the latter pathway is included. Finally, we briefly mention other associated aspects of this photocatalysis, including the possible promotion of H2 production with visible light via resonant excitation of the surface plasmon of Au nanoparticles, the use of single-metal (Au, Pt) atom catalysts and of yolk-shell nanostructures, and the reduction of organic molecules. We end with a brief personal perspective on the possible generality of the concepts introduced in this Critical Review.

Surface decorated metal carbonyl clusters: bridging organometallic molecular clusters and atomically precise ligated nanoclusters

In this Frontier Article, the work carried out within our research group in Bologna in the field of surface decorated metal carbonyl clusters will be outlined and put in a more general context. After a short Introduction, clusters composed of a metal carbonyl core decorated on the surface by metal-ligand fragments will be analyzed. Both metal-ligand fragments behaving as Lewis acids and Lewis bases will be considered. Then, the focus will be moved to clusters composed of a naked metal core decorated and stabilized on the surface by metal-carbonyl fragments. The structure and bonding (where theoretical studies are available) of such surface decorated metal carbonyl clusters will be presented, and compared to atomically precise ligated nanoclusters.

Single Molecular Dispersion of Crown Ether-Decorated Cobalt Phthalocyanine on Carbon Nanotubes for Robust CO2 Reduction through Host-Guest Interactions

Immobilizing molecular catalysts on electro-conductive supports (for example, multi-walled carbon nanotubes, CNTs) represent a promising way to well-defined catalyst/support interfaces, which has shown appreciable performance for catalytic transformation. However, their full potential is far from achieved due to insufficient utilization of the intrinsic activity for each immobilized molecular catalyst, especially at loadings that should allow decent current densities. In the present work, we discover host-guest interaction between tetra-crown ether substituted cobalt phthalocyanine and metal ions, for example K+ ions, not only eliminate catalyst aggregation at immobilization procedures but also reinforce catalyst/support interactions by additional electrostatic attractions under operational conditions. Through simple dip-coating procedures, a successful single molecular dispersion is achieved. Such a catalyst/electrode interface is stable and can selectively catalyze CO2-to-CO conversion with Faradaic efficiency over 96%. Importantly, this interface maintains an almost unchanged turnover frequency (TOF) across all loading conditions, implying a full utilization of the intrinsic activity of supported molecular catalysts. Therefore, a simultaneous achievement of high TOF and high current density (TOF of 111 s-1 at 38 mA cm-2) is achieved, in an aqueous H-type electrolyzer at an overpotential of 570 mV.

A Molecular Catalyst-Driven Sustainable Zinc-Air Battery Assembly

Bidirectional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts are key for molecular oxygen-centric renewable energy transduction via metal-air batteries. Here, a molecular cobalt complex is covalently tethered on a strategically functionalized silica surface that displayed both ORR and OER in alkaline media. The detailed X-ray absorbance spectroscopy (XAS) studies indicate that this catalyst retains its intrinsic molecular features while playing a central role during bidirectional electrocatalysis and demonstrating a relatively lower energy gap between O2/H2O interconversions. This robust molecular catalyst-silica composite (deposited on a porous carbon paper) is assembled along with a zinc foil and polymeric gel membrane to devise an active single-stack quasi-solid zinc-air battery (ZAB) setup. This quasi-solid ZAB assembly displayed impressive power density (60 mW cm-2@100 mA cm-2), specific capacity (818 mAh g-1@ 5mA cm-2), energy density (757 Whkg-1 @5mA cm-2), and elongated charging/discharging life (28 h). An appropriate assembly of these ZAB units is able to power practical electronic appliances, requiring ≈1.6-6.0V potential requirements.

Structure-Reactivity Relationship of Zeolite-Confined Rh Catalysts for Hydroformylation of Linear α-Olefins

Substituting the molecular metal complexes used in the industrial olefin hydroformylation process is of great significance in fundamental research and practical application. One of the major difficulties in replacing the classic molecular metal catalysts with supported metal catalysts is the low chemoselectivity and regioselectivity of the supported metal catalysts because of the lack of a well-defined coordination environment of the metal active sites. In this work, we have systematically studied the influences of key factors (crystallinity, alkali promoters, etc.) of the Rh-MFI zeolite catalysts on their performances for the hydroformylation of long-chain α-olefins (LAOs). With the help of comprehensive spectroscopy and electron microscopy characterization results, we can correlate the structural features of various Rh-MFI catalysts and their catalytic performances. The resultant structure-reactivity relationship guides us to prepare a nanosized Rh-MFI catalyst, which exhibits about a 3-fold improvement in specific activity compared to the Rh-MFI catalyst with conventional crystallite sizes and maintains very high regioselectivity for hydroformylation of LAOs.

Site-Specific for CO2 Photoreduction with Single-Atom Ni on Strained TiO2-x Derived from Bimetallic Metal-Organic Frameworks

The photocatalytic reduction of CO2 in water to produce fuels and chemicals is promising while challenging. However, many photocatalysts for accomplishing such challenging task usually suffer from unspecific catalytic active sites and the inefficient charge carrier's separation. Here, a site-specific single-atom Ni/TiO2-x catalyst is reported by in situ topological transformation of Ni-Ti-EG bimetallic metal-organic frameworks. The loading of nickel nanoparticles or individual atoms, which act as specific active sites, can be precisely regulated by chelating agents through the partial removal of nickel and adjacent oxygen atoms. Furthermore, the degree of lattice strain in Ni/TiO2-x catalysts, which improves the separation efficiency of charge carriers, can be modulated by fine-tuning the transformation process. By leveraging the anchored nickel atoms and the strained TiO2, the optimized NiSA0.27/TiO2-x shows a CO generation rate of 86.3 µmol g-1 h-1 (288 times higher than that of NiNPs/TiO2-x) and CO selectivity of up to 92.5% for CO2 reduction in a pure-water system. This work underscores the importance of tailoring lattice strain and creating specific single-atom active sites to facilitate the efficient and selective reduction of CO2.

Nitrogen Enriched Tröger's Base Polymers of Intrinsic Microporosity for Heterogeneous Catalysis

Heterogeneous catalysis is significantly enhanced by the use of highly porous polymers with specific functionalities, such as basic groups, which accelerate reaction rates. Polymers of intrinsic microporosity (PIMs) provide a unique platform for catalytic reactions owing to their high surface areas and customizable pore structures. We herein report a series of Tröger's base polymers (TB-PIMs) with enhanced basicity, achieved through the incorporation of nitrogen-containing groups into their repeat units, such as triazine and triphenylamine. These polymers offer a perfect balance between the pore "swellability", which allows the use of substrates of various dimensions, and the basicity of their repeat units, which facilitates the use of reactants with diverse acidity. The catalytic activity is evaluated through the Knoevenagel condensation of benzaldehydes and various methylene species, conducted in the presence of ethanol as a green solvent and using a 1:1 ratio of the two reagents. The results highlight a significant improvement, with reactions reaching completion using just a 1% molar ratio of catalysts and achieving a 3-fold enhancement over previous results with 4-tert-butyl-benzaldehyde. Computational modeling confirms that the enhanced basicity of the repeat units is attributable to the polymer design. Additionally, preliminary studies are undertaken to assess the kinetics of the catalyzed condensation reaction.

Designer topological-single-atom catalysts with site-specific selectivity

Designing catalysts with well-defined, identical sites that achieve site-specific selectivity, and activity remains a significant challenge. In this work, we introduce a design principle of topological-single-atom catalysts (T-SACs) guided by density functional theory (DFT) and Ab initio molecular dynamics (AIMD) calculations, where metal single atoms are arranged in asymmetric configurations that electronic shield topologically misorients d orbitals, minimizing unwanted interactions between reactants and the support surface. Mn1/CeO2 catalysts, synthesized via a charge-transfer-driven approach, demonstrate superior catalytic activity and selectivity for NOx removal. A life-cycle assessment (LCA) reveals that Mn1/CeO2 significantly reduces environmental impact compared to traditional V-W-Ti catalysts. Through in-situ spectroscopic characterizations combined with DFT calculations, we elucidate detailed reaction mechanisms. This study establishes T-SACs as a promising class of catalysts, offering a systematic framework to address catalytic challenges by defining site characteristics. The concept highlights their potential for advancing selective catalytic processes and promoting sustainable technologies.

Synergistic Nanoscale Mn3O4-CoO-Co Heterojunctions for Boosting the Selectivity in Hydrogenation of Nitrostyrenes and Nitroarenes

Metal-metal oxide interface catalysts are in high demand for advanced catalytic applications due to their multi-component active sites, which facilitate synergistic cooperation where a single component alone cannot effectively promote the desired reaction. Demonstrated herein graphene oxide-supported nanoscale Mn3O4-CoO-Co as highly efficient catalysts for hydrogenation of nitro styrenes/nitro arenes to amino styrenes/arenes under mild reaction conditions (0.5 MPa and 100 °C in 1 : 1 THF/water). Charge relocalization at the Co-CoO-Mn3O4 heterojunction interfaces, primarily driven by Mn3O4, significantly improves reaction selectivity. Replacing Mn3O4 with MnO or using other supported bimetallic CoMnOx catalysts decreases selectivity, leading to the formation of a mixture of products. The catalyst demonstrated remarkable selectivity in converting nitro groups to amines, even in the presence of highly reactive functional groups such as C=C, O-C=O, C=O, C≡N, chalcones, and halides. It also exhibited high yields, multiple reusability, and a broad substrate scope. This study demonstrates how Mn3O4, in synergy with CoO-Co, fine-tunes selectivity, paving the way for the development of advanced metal-metal oxide interface catalysts to enhance both selectivity and efficiency in organic transformations.

Catalyst to cure: applications of a new copper-based nanocatalyst in organic synthesis and cancer treatment

This research explores the diverse applications of copper(0) nanoparticles grafted onto boron carbon nitride nanosheets, using dill leaf extract as a natural reducing and stabilizing agent. This nanocatalyst efficiently catalyzes the synthesis of tetrazole and aniline derivatives, demonstrating good recyclability and promising potential in cancer therapy. By merging sustainability with innovation, this nanocatalyst offers transformative solutions in both synthesis and medical fields.

Electronic Structure Regulated Carbon-Based Single-Atom Catalysts for Highly Efficient and Stable Electrocatalysis

Single-atom-catalysts (SACs) with atomically dispersed sites on carbon substrates have attained great advancements in electrocatalysis regarding maximum atomic utilization, unique chemical properties, and high catalytic performance. Precisely regulating the electronic structure of single-atom sites offers a rational strategy to optimize reaction processes associated with the activation of reactive intermediates with enhanced electrocatalytic activities of SACs. Although several approaches are proposed in terms of charge transfer, band structure, orbital occupancy, and the spin state, the principles for how electronic structure controls the intrinsic electrocatalytic activity of SACs have not been sufficiently investigated. Herein, strategies for regulating the electronic structure of carbon-based SACs are first summarized, including nonmetal heteroatom doping, coordination number regulating, defect engineering, strain designing, and dual-metal-sites scheming. Second, the impacts of electronic structure on the activation behaviors of reactive intermediates and the electrocatalytic activities of water splitting, oxygen reduction reaction, and CO2/N2 electroreduction reactions are thoroughly discussed. The electronic structure-performance relationships are meticulously understood by combining key characterization techniques with density functional theory (DFT) calculations. Finally, a conclusion of this paper and insights into the challenges and future prospects in this field are proposed. This review highlights the understanding of electronic structure-correlated electrocatalytic activity for SACs and guides their progress in electrochemical applications.

Catalytic applications of organic-inorganic hybrid porous materials

Organic-inorganic hybrid porous materials (OIHMs) inherit the unique properties from both organic and inorganic components, and the flexibility in the incorporation of functional groups renders the OIHMs an ideal platform for the construction of catalytic materials with multiple active sites. The preparation of OIHMs with precise locations of organic-inorganic components and tunable structures is one of the important topics for the catalytic application of OIHMs, but it is still very challenging. In this feature article, we describe our work related to the preparation of OIHMs via confining active sites in the nanostructure and a layer-by-layer assembly method and their applications in acid-base catalysis, catalytic hydrogenation and photocatalysis with a focus on the elucidation of the synergistic effects of different active sites and the unique properties of OIHMs in catalysis.

A universal strategy for the synthesis of transition metal single atom catalysts toward electrochemical CO2 reduction

Herein, a pyrolysis-induced precursor transformation strategy has been proposed. Using pre-synthesized PDA-M as a precursor, the production of transition metal single atom catalysts (SACs) has been achieved, with compositional flexibility at high metal loadings. In particular, the Ni SAC sample has shown promising CO selectivity when evaluated for the electrochemical CO2 reduction reaction, reaching 29.8 mA cm-2 CO partial current density and 90.3% CO faradaic efficiency at -1.05 V vs. RHE.

Optimization of Metal-Support Cooperation for Boosting the Performance of Supported Gold Catalysts for the Borylation of C-O and C-N Bonds

The cooperation of multiple catalytic components is a powerful tool for intermolecular bond formation, specifically, cross-coupling reactions. Supported metal catalysts have interfacial sites between metal nanoparticles and their supports where multiple catalytic elements can work in cooperation to efficiently promote intermolecular reactions. Hence, the establishment of novel guidelines for designing active interfacial sites of supported metal catalysts is indispensable for heterogeneous catalysts which enable efficient cross-coupling reactions. In this article, we performed kinetic and theoretical studies to elucidate the effect of metal-support cooperation for the borylation of C-O bonds by supported gold catalysts and revealed that the Lewis acid density of the supports determined the number of active sites at which metal nanoparticles (NPs) and Lewis acid at the surface of the supports work in cooperation. Furthermore, DFT calculations revealed that strong adsorption of diborons at the interface between Au NPs and supports and a decrease in the LUMO level of adsorbed diboron were responsible for efficient C-O bond borylation. Supported Au catalysts with the optimized metal-metal oxide cooperation sites, namely, Au/α-Fe2O3 catalyst, showed excellent activity for C-O bond borylation, and also enabled the synthesis of organoboron compounds by using continuous-flow reactions. Furthermore, Au/α-Fe2O3 showed high activity for direct C-N bond borylation without the transformation of amino groups to ammonium cations. The results described herein suggest that the optimization of metal-metal oxide cooperation is beneficial for taking full advantage of the potential performance of supported metal catalysts for intermolecular reactions.

Synthesis and catalytic application of nanostructured metal oxides and phosphates

The design and development of new high-performance catalysts is one of the most important and challenging issues to achieve sustainable chemical and energy production. This Feature Article describes the synthesis of nanostructured metal oxides and phosphates mainly based on earth-abundant metals and their thermocatalytic application to selective oxidation and acid-base reactions. A simple and versatile methodology for the control of nanostructures based on crystalline complex oxides and phosphates with diverse structures and compositions is proposed as another approach to catalyst design. Herein, two unique and verstile methods for the synthesis of metal oxide and phosphate nanostructures are introduced; an amino acid-aided method for metal oxides and phosphates and a precursor crystallization method for porous manganese oxides. Nanomaterials based on perovskite oxides, manganese oxides, and metal phosphates can function as effective heterogeneous catalysts for selective aerobic oxidation, biomass conversion, direct methane conversion, one-pot synthesis, acid-base reactions, and water electrolysis. Furthermore, the structure-activity relationship is clarified based on experimental and computational approaches, and the influence of oxygen vacancy formation, concerted activation of molecules, and the redox/acid-base properties of the outermost surface are discussed. The proposed methodology for nanostructure control would be useful not only for the design and understanding of the complexity of metal oxide catalysts, but also for the development of innovative catalysts.

Sequence-Controlled Electrochemical Immobilization of Catalyst-Photosensitizer Oligomers for Tuning Photoelectrochemical Behaviors

Immobilizing catalysts and photosensitizers on an electrode surface is crucial in interfacial energy conversion. However, their combination for optimizing catalytic performance is an unpredictable challenge. Herein, we report that catalyst and photosensitizer monomers are selectively grafted one-by-one addition onto the electrode surface by interfacial electrosynthesis to achieve composition and sequence-controlled oligomer photoelectrocatalytic monolayers. This electrosynthesis relies on the oxidative coupling reaction of carbazole and the reductive coupling reaction of vinyl on the catalyst and photosensitizer monomers, and it initiates on self-assembled monolayers and propagates with alternating positive and negative potentials. Each addition and completion of the target monomer can be quantitatively identified and monitored by optical and electrical responses and their linear coefficients as a function of reaction steps. The resulting composition and sequence-controlled monolayers exhibit tuning electrocatalytic behaviors including water splitting and CO2 reduction, indicating an efficient way to optimize the electro- and photocatalytic functions and performance of molecular materials.

Regulating interaction with surface ligands on Au25 nanoclusters by multivariate metal-organic framework hosts for boosting catalysis

While atomically precise metal nanoclusters (NCs) with unique structures and reactivity are very promising in catalysis, the spatial resistance caused by the surface ligands and structural instability poses significant challenges. In this work, Au25(Cys)18 NCs are encapsulated in multivariate metal-organic frameworks (MOFs) to afford Au25@M-MOF-74 (M = Zn, Ni, Co, Mg). By the MOF confinement, the Au25 NCs showcase highly enhanced activity and stability in the intramolecular cascade reaction of 2-nitrobenzonitrile. Notably, the interaction between the metal nodes in M-MOF-74 and Au25(Cys)18 is able to suppress the free vibration of the surface ligands on the Au25 NCs and thereby improve the accessibility of Au sites; meanwhile, the stronger interactions lead to higher electron density and core expansion within Au25(Cys)18. As a result, the activity exhibits the trend of Au25@Ni-MOF-74 > Au25@Co-MOF-74 > Au25@Zn-MOF-74 > Au25@Mg-MOF-74, highlighting the crucial roles of microenvironment modulation around the Au25 NCs by interaction between the surface ligands and MOF hosts.

Rational Design of Earth-Abundant Catalysts toward Sustainability

Catalysis is crucial for clean energy, green chemistry, and environmental remediation, but traditional methods rely on expensive and scarce precious metals. This review addresses this challenge by highlighting the promise of earth-abundant catalysts and the recent advancements in their rational design. Innovative strategies such as physics-inspired descriptors, high-throughput computational techniques, and artificial intelligence (AI)-assisted design with machine learning (ML) are explored, moving beyond time-consuming trial-and-error approaches. Additionally, biomimicry, inspired by efficient enzymes in nature, offers valuable insights. This review systematically analyses these design strategies, providing a roadmap for developing high-performance catalysts from abundant elements. Clean energy applications (water splitting, fuel cells, batteries) and green chemistry (ammonia synthesis, CO2 reduction) are targeted while delving into the fundamental principles, biomimetic approaches, and current challenges in this field. The way to a more sustainable future is paved by overcoming catalyst scarcity through rational design.

Confinement-Driven Dimethyl Ether Carbonylation in Mordenite Zeolite as an Ultramicroscopic Reactor

ConspectusThe conversion of C1 molecules to methyl acetate through the carbonylation of dimethyl ether in mordenite zeolite is an appealing reaction and a crucial step in the industrial coal-to-ethanol process. Mordenite zeolite has large 12-membered-ring (12MR) channels (7.0 × 6.5 Å2) and small 8MR channels (5.7 × 2.6 Å2) connected by a side pocket (4.8 × 3.4 Å2), and this unique pore architecture supplies its high catalytic activity to the key step of carbonylation. However, the reaction mechanism of carbonylation in mordenite zeolite is not thoroughly established in that it is able to explain all experimental phenomena and improve its industrial applications, and the classical potential energy surface exerted by static density function theory calculations cannot reflect the reaction kinetics under realistic conditions because the diffusion kinetics of bulk DME (kinetic dimeter: 4.5 Å) and methyl acetate (MA, kinetic dimeter: 5.5 Å) were not well considered and their restricted diffusion in the narrow side pocket and 8MR channels may greatly alter the integrated kinetics of DME carbonylation in mordenite zeolite. Moreover, the precise illustration of the dynamic behaviors of the ketene intermediate and its derivatives (surface acetate and acylium ion) confined within various voids in mordenite has not been effectively portrayed.Advanced ab initio molecular dynamics (AIMD) simulations with or without the acceleration of enhanced sampling methods provide tremendous opportunities for operando modeling of both reaction and diffusion processes and further identify the geometrical structure and chemical properties of the reactants, intermediates, and products in the different confined voids of mordenite under realistic reaction conditions, which enables high consistency between computations and experiments.In this Account, the carbonylation process in mordenite is comprehensively described by the results of decades of continuous research and newly acquired knowledge from both multiscale simulations and in-(ex-)situ spectroscopic experiments. Three primary steps (DME demethylation to surface methoxy species (SMS), carbon-carbon bond coupling between SMS and CO to acetyl species, and methyl acetate formation by acetyl species and methanol/DME) have been respectively studied with a careful consideration of different molecular factors (reactant distribution, concentration, and attack mode). By utilizing the free-energy surface of diffusion and reaction obtained from AIMD simulations, a comprehensive reaction/diffusion kinetic model was formulated for the first time, illustrating the entire zeolite catalytic process. In this context, a comprehensive and informative analysis of the reaction kinetics of carbonylation in mordenite, including the function of the 12MR channels, 8MR channels, and side pockets in the adsorption, diffusion, and reaction of DME carbonylation, was performed. The different channels of mordenite play different roles in all ordered reaction steps, illustrating a highly organized ultramicroscopic reactor that is encompassed.

Influence of Solid Alkaline Photocatalysts Irradiated with UV Light on Fuel Properties of Palm Oil Biodiesel

TiO2 nanoparticles are full of porosity that can be impregnated with a strong alkaline catalyst CH3ONa to form a TiO2/CH3ONa catalyst. TiO2 of the anatase phase, which is a semiconductor material, has been a prominent photocatalyst due to its excited photocatalyst activity, chemical and biological stability, and nontoxicity. The CH3ONa compound has been widely used as a catalyst for transesterification. Although the synthesized photocatalyst TiO2 powder with CH3ONa is anticipated to greatly enhance the transesterification efficiency, leading to improving biodiesel properties, relevant studies have not been found. After the photocatalyst was prepared, a reactant mixture of palm oil, methanol, and heterogeneous catalyst TiO2/CH3ONa was illuminated by ultraviolet (UV) light from light-emitting diode (LED) lamps. The experimental results revealed that the formation of fatty acid methyl esters was significantly increased to 98.4% with ultraviolet-light illumination for the molar ratio of methanol/palm oil equal to 6 and 3 wt % catalyst addition. The decrease of the catalyst amount to 2 wt % resulted in a slight decrease of the fatty acid methyl esters to 97.06 wt %. The lowest kinematic viscosity and acid value and the highest distillation temperature, heating value, and cetane index were observed under the above reaction conditions. The distillation temperature and cetane index were increased while the acid value was decreased under ultraviolet illumination on the reactant mixture. Consequently, the optimum preparing conditions for biodiesel production were 6 and 3 wt % for the molar ratio of methanol/palm oil and catalyst addition under UV-light irradiation.

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

Organocatalysis has become a powerful tool in synthetic chemistry, providing a cost-effective alternative to traditional catalytic methods. The immobilisation of organocatalysts offers the potential to increase catalyst reusability and efficiency in organic reactions. This article reviews the key parameters that influence the effectiveness of immobilised organocatalysts, including the type of support, immobilisation techniques and the resulting interactions. In addition, the influence of these factors on catalytic activity, selectivity and recyclability is discussed, providing an insight into optimising the performance of immobilised organocatalysts for practical applications in organic chemistry.

De novo construction of amine-functionalized metal-organic cages as heterogenous catalysts for microflow catalysis

Microflow catalysis is a cutting-edge approach to advancing chemical synthesis and manufacturing, but the challenge lies in developing efficient and stable multiphase catalysts. Here we showcase incorporating amine-containing metal-organic cages into automated microfluidic reactors through covalent bonds, enabling highly continuous flow catalysis. Two Fe4L4 tetrahedral cages bearing four uncoordinated amines were designed and synthesized. Post-synthetic modifications of the amine groups with 3-isocyanatopropyltriethoxysilane, introducing silane chains immobilized on the inner walls of the microfluidic reactor. The immobilized cages prove highly efficient for the reaction of anthranilamide with aldehydes, showing superior reactivity and recyclability relative to free cages. This superiority arises from the large cavity, facilitating substrate accommodation and conversion, a high mass transfer rate and stable covalent bonds between cage and microreactor. This study exemplifies the synergy of cages with microreactor technology, highlighting the benefits of heterogenous cages and the potential for future automated synthesis processes.

Thermocatalytic epoxidation by cobalt sulfide inspired by the material's electrocatalytic activity for oxygen evolution reaction

New discoveries in catalysis by earth-abundant materials can be guided by leveraging knowledge across two sub-disciplines of heterogeneous catalysis: electrocatalysis and thermocatalysis. Cobalt sulfide has been reported to be a highly active electrocatalyst for the oxygen evolution reaction (OER). Under these oxidative conditions, cobalt sulfide forms oxidized surfaces that outperform directly prepared cobalt oxide in OER catalysis. We postulated that the catalytic activity of oxidized cobalt sulfide for OER could reflect a more general ability to catalyze O-transfer reactions. Herein, we show that cobalt sulfide (CoS x ) indeed catalyzes the epoxidation of cyclooctene, a thermal O-transfer reaction. Similarly to OER, the surface-oxidized CoS x formed under reaction conditions outperformed the directly prepared cobalt oxide, hydroxide, and oxyhydroxide for epoxidation catalysis. Another notable phenomenological parallel to OER was revealed by the electron paramagnetic resonance (EPR) analysis of all spent Co-based catalysts that showed significant structural changes and the formation of paramagnetic Co(ii) and Co(iv) species. Mechanistic investigations suggest that a higher density of Co(ii) and/or an easier formation of high-valent Co species in the case of surface-oxidized cobalt sulfide is responsible for its high activity as an epoxidation catalyst. Our results provide important insight into the surface chemistry of Co-based catalysts and show the potential of oxidized CoS x as an earth-abundant catalyst for O-transfer reactivity beyond OER. This work highlights the utility of bridging electrocatalysis and thermocatalysis for the development of more sustainable chemical processes.