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The rational design of single atom‐based catalysts and precise elucidation of the synergistic interaction between the metal site and substrate are pivotal to identifying the real active sites and explicating the catalytic mechanisms at the atomic scale, thus contributing to the development of high‐performance catalysts for diverse industrial implementations. Herein, a Ru single‐atom doping strategy is developed to activate the MoC substrate with superior hydrogen evolution reaction (HER) activity in an alkaline medium. The atomically dispersed Ru sites are elaborately doped into MoC nanoparticles loaded on 3D N‐doped carbon nanoflowers (Ru‐SAs@MoC/NCFs hereafter). The experimental results and theoretical calculations manifest that the atomically isolated Ru dopants can effectively trigger the Mo sites with thermodynamically favorable water adsorption/dissociation energies and facilitate the OH− desorption on Ru sites and H adsorption on N sites, thus synergistically expediating the overall alkaline HER kinetics. As such, the well‐designed Ru‐SAs@MoC/NCFs demonstrate extraordinary HER activity with a low overpotential of 16 mV at 10 mA cm−2 in 1.0 m KOH electrolyte, outperforming Pt/C benchmark and a vast of molybdenum/ruthenium‐based HER catalysts reported to date. These findings disclose the alkaline HER mechanistic induced by the atomic doping modulation and suggest a design principle of high‐efficiency electrocatalysts via the atomic‐level manipulation leverage. [ABSTRACT FROM AUTHOR]

Biomass valorisation through the selective oxidation of carbohydrate and lipid derivatives offers access to an array of platform chemicals through energy- and atom-efficient catalytic processes. Supported metal nanoparticles are promising catalysts for the aerobic selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), but typically require strong liquid base to achieve high selectivity. Here, we explore the utility of MgO as a solid base support for the Ru-catalysed aerobic oxidation of HMF, obtaining 68% FDCA yield at 160°C and 1.5 MPa of O2 using <1 mol-% metal. Biomass offers a sustainable alternative source of carbon to existing fossil resources that underpin the global chemical industry – on which we rely for fuels, plastics and pharmaceuticals. Combining ruthenium metal with Earth-abundant magnesium oxide creates an efficient catalyst for transforming sugar components of waste biomass into a valuable precursor for the sustainable manufacture of plastics. (Image credit: Priya Lokhande.) This article belongs to the 10th Anniversary Collection of RACI and AAS Award papers. [ABSTRACT FROM AUTHOR]

The catalytic activity of a Ru complex 1, bearing a fused π‐conjugated imidazo[1,2–a][1,8]naphthyridine‐based mesoionic carbene (MIC) ligand, is examined for the oxidation of primary amines. Complex 1 affords nitrile or imine depending on the nature of the terminal oxidants and solvents used in the reactions. Primary amines are converted to nitriles using NaIO4 in EtOAc/H2O mixture, whereas imines are obtained under O2 balloon pressure in toluene. A variety of nitriles and imines are accessed with high yields and selectivity. A set of control experiments, reaction profiles, and kinetic studies are undertaken to disclose the mechanistic details for nitrile and imine formation. The catalytic reactions illustrate a subtle dependency on the choice of oxidants and solvents in the oxidation of primary amines. [ABSTRACT FROM AUTHOR]

A mechanochemical‐enabled Ru‐catalyzed regioselective synthesis of 3,4‐isoxazoles and 3,4,5‐isoxazoles from terminal and internal alkynes and hydroxyimidoyl chlorides is reported. This solid‐state and solvent‐free approach carefully examines the impact of the milling conditions on regiocontrol in 1,3‐dipolar cycloadditions using mechanochemical means. The study reveals that milling frequency, jar material, and the choice of liquid additive for liquid‐assisted grinding (LAG) significantly influence the catalytic activity of the Ru catalyst. Transmission electron microscope (TEM) analysis confirms the crucial role of coordinating liquid additives such as acetone and cyclopentyl methyl ether (CPME) in stabilizing and reducing the size of the in‐situ formed Ru nanoparticles, which is essential for catalytic activity. The applicability of this protocol is further demonstrated through the synthesis of a library of 3,4‐ and 3,4,5‐isoxazoles from a wide range of terminal and internal alkynes with varying physical states and electronic properties that highlights the potential of this method for the synthesis of more complex target molecules. [ABSTRACT FROM AUTHOR]

The effectuation of pH‐universal electrocatalysis is highly attractive but still challenging for the hydrogen evolution reaction (HER). It appeals for not only the facilitated electron transport but also the kinetical proton mass transfer. In this study, a via‐hole Ru/MoO2 confined heterostructure is profiled as a metal‐support platform for the electron/mass transfer‐boosted pH‐universal HER studies. It is indicated that the as‐formed Ru─O─Mo bridge can modulate the electronic transport at the interface, and the proton adsorption and transfer are kinetically derived by the intensified metallic Ru─Ru bond. Resultantly, the Ru/MoO2 heterostructure stably attains the Pt‐beyond HER activity with an ultralow overpotential of 9.2 mV at 10 mA cm−2 in 1 m KOH, and also achieves the competitive HER activity and stability in the acidic/neutral electrolytes. Both the experimental and computational results reveal the accelerated HER kinetics is attributable to the intensive mass transfer through the interfacial Ru→MoO2 hydrogen spillover effect. This work opens up the opportunities to rationalize the advanced metal‐support HER electrocatalysts through the interfacial hydrogen spillover effect and metallic bond engineering. [ABSTRACT FROM AUTHOR]

A novel phosphine‐free ruthenium pincer complex based on an NNN pincer ligand has been prepared and fully characterized. The complex was subsequently employed as an efficient catalyst for the N‐methylation of amines and the direct N‐methylation of nitroarenes using methanol as a C1 source under mild reaction conditions following the borrowing‐hydrogen approach. Both of the catalytic transformations were performed with only catalytic amounts of base under closed air conditions without using any other additives. [ABSTRACT FROM AUTHOR]

Fischer-Tropsch (FT) synthesis is an important module for the production of clean and sustainable fuels and chemicals, making it a topic of considerable interest in energy research. This mini-review covers the current literature on FT catalysis and offers insights into the primary products, the nuances of the FT reaction, and the product distribution, with particular attention to the Anderson-Schulz-Flory distribution (ASFD) and known deviations from this fundamental concept. Conventional FT catalysts, particularly Fe- and Co-based catalysis systems, are reviewed, highlighting their central role and the influence of water and water-gas shift (WGS) activity on their catalytic behavior. Various mechanisms of catalyst deactivation are also investigated, and the high methanation activity of Co-based catalysts is illustrated. To make this complex field accessible to a broader audience, we explain conjectured reaction mechanisms, namely, the carbide mechanism and CO insertion. We discuss the complex formation of a wide range of products, including olefins, kerosenes, branched hydrocarbons, and by-products such as alcohols and oxygenates. The article goes beyond the traditional scope of FT catalysis by addressing topics of current interest, including the direct hydrogenation of CO2 for power-to-X applications and the use of bifunctional catalysts to produce tailored FT products, most notably for the production of sustainable aviation fuel (SAF). This mini-review provides a holistic overview of the evolving landscape of FT catalysts and is aimed at both experienced researchers and those new to the field while covering current and emerging trends in this important area of energy research. [ABSTRACT FROM AUTHOR]

Bio-based polymers are attracting increasing interest as alternatives to harmful and environmentally concerning non-biodegradable fossil-based products. In particular, bio-based polymers may be employed as ligands for the preparation of metal nanoparticles (M(0)NPs). In this study, chitosan (CS) was used for the stabilization of Ru(0) and Rh(0) metal nanoparticles (MNPs), prepared by simply mixing RhCl3 × 3H2O or RuCl3 with an aqueous solution of CS, followed by NaBH4 reduction. The formation of M(0)NPs-CS was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Analysis (EDX), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). Their size was estimated to be below 40 nm for Rh(0)-CS and 10nm for Ru(0)-CS by SEM analysis. M(0)NPs-CS were employed for the hydrogenation of (E)-cinnamic aldehyde and levulinic acid. Easy recovery by liquid-liquid extraction made it possible to separate the catalyst from the reaction products. Recycling experiments demonstrated that M(0)NPs-CS were highly efficient up to four times in the best hydrogenation conditions. The data found in this study show that CS is an excellent ligand for the stabilization of Rh(0) and Ru(0) nanoparticles, allowing the production of some of the most efficient, selective and recyclable hydrogenation catalysts known in the literature. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of novel ruthenium(ii) complexes with nitron-type N-heterocyclic carbene ligands containing chelating (N -arylcarbamoyl)methyl or carboxymethyl groups have been synthesized. Their evaluation as precatalysts in the hydrogenation of ketones has revealed that the complex containing three N -mesityl groups (one on the carbamoyl- methyl moiety and two on the triazole moiety) is the most efficient one. [ABSTRACT FROM AUTHOR]

The availability of catalytic sites for contact with reactants is a key issue to improve the performance of a catalyst, where constructing hollow structured nanomaterials has been considered as an effective strategy. Here, an N-doped carbon supported Ru catalyst with an interior cavity was synthesized by etching a MOF-derived core–shell precursor, in which metal Ru can be highly dispersed in the porous shell. This catalyst shows 98.7% conversion and >99% selectivity towards p-chloroaniline in the hydrogenation of p-chloronitrobenzene, which is better than the corresponding supported catalyst. Moreover, it also displays excellent stability with 5 cycle runs and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterization techniques and control experiments reveal the advantage of the unique structure to promote the mass transport and adsorption of reactant molecules on Ru sites. This work provides a novel strategy to design an efficient Ru-based catalyst for chemoselective hydrogenation. [ABSTRACT FROM AUTHOR]

Anions of carboxylic acids are widely used as the promoters of ruthenium-catalyzed reactions of C—H activation of substrates containing an N-donar directing group. The promoting effect of structure of anions of aliphatic and (hetero)aromatic carboxylic acids on the C—H arylation of benzene, furan, and thiophene rings in benzo[d]imidazol-2-yl-(hetero)arenes, wherein the benzimidazole moiety played the role of N-donor directing group, was evaluated. It was found that the structural effect of carboxylate anion on the efficiency of promotion of the catalytic system can significantly vary upon the arylation of different substrates. Adamantane-1-carboxylic acid was proposed as the most effective and universal promoter, based on which a new efficient catalytic system was developed for the selective arylation of benzo[d]imidazol-2-yl-(hetero)arenes. [ABSTRACT FROM AUTHOR]

An atom‐ and step‐economical and redox‐neutral cascade reaction enabled by asymmetric bimetallic relay catalysis by merging a ruthenium‐catalyzed asymmetric borrowing‐hydrogen reaction with copper‐catalyzed asymmetric Michael addition has been realized. A variety of highly functionalized 2‐amino‐5‐hydroxyvaleric acid esters or peptides bearing 1,4‐non‐adjacent stereogenic centers have been prepared in high yields with excellent enantio‐ and diastereoselectivity. Judicious selection and rational modification of the Ru catalysts with careful tuning of the reaction conditions played a pivotal role in stereoselectivity control as well as attenuating undesired α‐epimerization, thus enabling a full complement of all four stereoisomers that were otherwise inaccessible in previous work. Concise asymmetric stereodivergent synthesis of the key intermediates for biologically important chiral molecules further showcases the synthetic utility of this methodology. [ABSTRACT FROM AUTHOR]

We report an investigation of catalyst performance for the decomposition of ammonia under industrially relevant conditions (high temperatures of up to 800 °C and an elevated pressure of 5 bar) with further emphasis on their stability at high reaction temperatures. The catalysts were applied and tested as coatings in 500 µm wide channels of microreactors. Nickel-based catalysts were studied and compared to a ruthenium-based catalyst supported on SiO2. The effect of the support on the catalytic performance was investigated, and CeO2-supported nickel catalysts were found to exhibit the highest activity. Promoters were applied to increase the NH3 decomposition activity of the Ni/CeO2 catalysts. The addition of cesium led to a slight reduction in activity, while lanthanum, calcium, and barium doping resulted in increased activity. In particular, the barium-doped Ni/CeO2 catalyst showed very high ammonia conversion and closed the activity gap with respect to ruthenium catalysts at reactor temperatures of 650 °C and higher. The hydrogen production rates achieved in this work were compared to values in the literature and were shown to exceed values found earlier for both nickel- and ruthenium-based catalysts. Furthermore, the ruthenium-based catalysts under investigation were rapidly deactivated at 700 °C, while the nickel-based catalysts did not show deactivation after 220 h on time on stream at 700 °C. [ABSTRACT FROM AUTHOR]

The integration of dual asymmetric catalysis is highly beneficial for the synthesis of organic molecules with multiple stereocenters. However, two major issues that need to be addressed are the intrinsic deactivation of dual-species and the extrinsic conflict of reaction conditions. To overcome these concerns, we have utilized the compartmental and thermoresponsive properties of poly(N-isopropylacrylamide) (PNIPAM) to develop a cross-linked PNIPAM-hydrogel-supported bifunctional catalyst. This catalyst is designed with Rh(diene) species situated on the outer surface and Ru(diamine) species positioned within the interior of the hydrogel. The compartmental function of PNIPAM in the middle overcomes intrinsic mutual deactivations between the dual-species. The thermoresponsive nature of PNIPAM allows for precise control of catalytic pathways in resolving external conflicts by controlling the reaction switching between an Rh-catalyzed enantioselective 1,4-addition at 50°C and a Ru-catalyzed asymmetric transfer hydrogenation (ATH) at 25°C. As we envisioned, this sequential 1,4-addition/reduction dual enantioselective cascade reaction achieves a transformation from incompatibility to compatibility, resulting in direct access to γ-substituted cyclic alcohols with dual stereocenters in high yields and enantio/diastereoselectivities. Mechanistic investigation reveals a reversible temperature transition between 50°C and 25°C, ensuring a cascade process comprising a 1,4-addition followed by the ATH process. Dual asymmetric catalysis is powerful for the synthesis of multi-stereocenter molecules, however, the integration of dual catalysts remains challenging due to the intrinsic deactivation of dual-species and extrinsic conflict of reaction conditions. Here, the authors develop a compartmental and thermoresponsive poly(N-isopropylacrylamide)-hydrogel-supported bifunctional catalyst to overcome these challenges. [ABSTRACT FROM AUTHOR]

Xylose is nowadays converted into xylitol, a popular special chemical sweetener. Xylitol can be used not only in the pharmaceutical and food industries, but also in cosmetics and synthetic resins because of its countless properties. Conventionally, xylitol is produced by slurry reactors operating in batch with dispersed or supported catalysts. Hydrogen is continuously fed to maintain a constant pressure. In this work, the kinetics of the reaction were investigated to find the optimal operating conditions to minimize the by-products obtained. Given the great performances shown by the new Ru/SiO2 sol–gel derived catalyst in glucose hydrogenation, in this work the mentioned catalyst was tested in the hydrogenation of xylose to xylitol both in batch and in continuous production to prove its stability and activity. [ABSTRACT FROM AUTHOR]

Nature uses reactive components embedded in biological membranes to perform light‐driven photosynthesis. Here, a model artificial photosynthetic system for light‐driven hydrogen (H2) evolution is reported. The system is based on liposomes where amphiphilic ruthenium trisbipyridine based photosensitizer (RuC9) and the H2 evolution reaction (HER) catalyst [Mo3S13]2− are embedded in biomimetic phospholipid membranes. When DMPC was used as the main lipid of these light‐active liposomes, increased catalytic activity (TONCAT ~200) was observed compared to purely aqueous conditions. Although all tested lipid matrixes, including DMPC, DOPG, DPPC and DOPG liposomes provided similar liposomal structures according to TEM analysis, only DMPC yielded high H2 amounts. In situ scanning electrochemical microscopy (SECM) measurements using Pd microsensors revealed an induction period of around 26 minutes prior to H2 evolution, indicating an activation mechanism which might be induced by the fluid‐gel phase transition of DMPC at room temperature. Stern‐Volmer‐type quenching studies revealed that electron transfer dynamics from the excited state photosensitizer are most efficient in the DMPC lipid environment giving insight for design of artificial photosynthetic systems using lipid bilayer membranes. [ABSTRACT FROM AUTHOR]

Barium oxide is a conventional promoter for various transition‐metal (TM) catalysts in ammonia synthesis. Ba‐promoted Ru catalysts are widely used for ammonia synthesis under mild reaction conditions. However, the promotion mechanism, including the active factor, remains unclear. In this study, the excellent promotion effect of barium oxynitride is reported, which creates anionic electrons in the lattice, forming an electride (BaOxNy:e−z) with the same rocksalt structure as BaO. The BaOxNy:e−z enhances the ammonia synthesis activity of the supported Ru catalyst by 40–100 fold compared with the BaO promotor. This study reveals that a low‐work‐function electron formed in the BaO lattice plays a pivotal role in the electronic promotion effect in catalytic ammonia synthesis, suggesting that BaOxNy:e−z formed near the surface during the ammonia synthesis reaction is an active species for the promotion effect of conventional BaO. [ABSTRACT FROM AUTHOR]

The worldwide demand for clean water is rising worldwide, yet wastewater decontamination is actually limited by the presence of refractory organic and inorganic compounds, calling for more efficient treatment methods. Here we review the use of ruthenium-based catalysts for the removal or transformation of pollutants at a concentration range of 1.0–100 mg/L under acid or neutral conditions. We focus on catalytic oxidation and reduction, and on the environmental impact of ruthenium catalysts. We discuss electrooxidation, photocatalytic oxidation, activation of inert oxidants, hydrogen-assisted reduction, electroreduction, and N–O bond activation. [ABSTRACT FROM AUTHOR]

Noble metal Pt‐based catalysts have slow water dissociation kinetics at high pH conditions, making it difficult for water molecules to be electrochemically activated. Utilizing ligand effect and strain effect to tailor catalytic active sites is a common method, while the understanding of mechanism of their interaction remains obscure due to the complexity of the process. This study proposes a pulse‐induced torsional strained PtRu mesocrystals (PtRu MCs) with 20 times higher mass activity than commercial Pt/C. The combination of experimental results and theoretical calculations reveals that the ligand effect induced by Ru doping accelerates the kinetics of the water dissociation reaction, while the pulse‐induced torsion strained dominates the thermodynamic optimization of the hydrogen adsorption reaction. The structure‐activity relationship defined by the synergistic effect under the complementary advantages of the strain and doping provides guidance for the design of future basic hydrogen evolution catalysts. The catalyst can run stably at 1 A cm−2 for 500 h, showing potential for industrial application. [ABSTRACT FROM AUTHOR]

Exploring highly active and robust catalysts, which have low precious metal content, to boost the kinetically sluggish oxygen evolution reaction (OER) is a key concern for hydrogen production via proton exchange membrane water electrolysis (PEMWE). Here, rational engineering of the morphology and the local geometric ligand environment of Ir and Ru catalysts are presented by using defect‐rich, lanthanum‐ and lithium‐doped Co3O4 nanofiber (LLCF) as substrate that promotes the electrocatalytic OER. Two catalysts, IrCoOx@LLCF and RuCoOx@LLCF, achieve mass activities of 1013.5 A gIr−1 and 1911.4 A gRu−1 in 0.1 m HClO4 at 300 mV overpotential, respectively, which are 26 and 50 times higher than that of commercial IrO2 and RuO2. Operando X‐ray absorption spectroscopy unveils the reversible structure of IrCoOx during the OER and the suppression of over‐oxidation of Co and Ir, giving rise to high stability. Density functional theory calculations reveal that the local geometric ligand engineering optimizes the binding of oxygenated species to the active sites, resulting in strongly enhanced catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ru(III) sites in solid micellar catalyst can be reversible switched to Ru0 clusters. • Ru(III) single-sites selectively catalyze the hydrogenation of functional groups. • Ru0 nanoclusters in contrast are very active for hydrogenating aromatic rings. Traditionally, catalytic active sites are robust; they do not change after a reaction. We show here that the Ru(III) active sites in a solid micellar Ru(III)@MCM catalyst can be controllably switched to Ru0 nanoclusters and vice versa by a mild treatment. The Ru(III) single-sites selectively catalyze the hydrogenation of functional groups such as carbonyl, and double and triple bonds in aromatic compounds via heterolytic H 2 activation. The Ru0 nanoclusters in contrast are very active for hydrogenating aromatic rings. Ru0 nanoclusters are reversibly formed from the Ru(III) sites via hydrolysis and reduction as shown by XAS, HRTEM, CO adsorption, and DFT calculations. The reported strategy offers reversible switching between oxidized and metallic states of Ru to perform different chemical transformations, achieving on-demand active sites. [ABSTRACT FROM AUTHOR]

In this study, two new Schiff base ligands, (E)-ethyl 2-(2-hydroxybenzylideneamino)-5,5,7,7-tetramethyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate (L1) and (E)-ethyl 2-(2-hydroxy-3-methoxybenzylideneamino)-5,5,7,7-tetramethyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate (L2), and their corresponding RuII complexes, [L1Ru(p-cymene)]Cl·2.5H2O (1) and [L2RuCl(p-cymene)]1.5H2O (2), were synthesized. The structures of Schiff bases and their RuII‐p‐cymene complexes were elucidated using microanalysis, magnetic susceptibility, molar conductivity, 1H-NMR, 13C-NMR, FT-IR, UV–Vis, LC–MS, and thermogravimetric analysis techniques. Octahedral structures for the obtained RuII‐p‐cymene complexes were proposed. The catalytic activities of the RuII‐p‐cymene complexes obtained after the characterization processes were investigated by using acetophenone derivatives in the transfer hydrogen reactions. The product conversions obtained as a result of catalytic studies were determined using GC–MS. When 4-bromoacetophenone was used as a substrate in the transfer hydrogen reactions, catalysts 1 and 2 showed good catalytic activity of 93% and 96%. [ABSTRACT FROM AUTHOR]

The fundamental insights of the reaction mechanism, especially the synergistic effect between oxygen vacancies and basic sites, are highly promising yet challenging for Ru-based catalysts during carbon dioxide (CO2) methanation. Herein, a series of Ru-based catalysts were employed to study the mechanism of CO2 methanation. It is found that Ru/CeO2 catalyst exhibits a much higher CO2 conversion (86%) and CH4 selectivity (100%), as well as excellent stability of 30 h due to the existence of abundant oxygen vacancies and weak basic sites. Additionally, the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations reveal that the formate formation step dominated the hydrogenation route on Ru/CeO2 catalyst, and the b-HCOO* could be the key intermediate due to b-HCOO* is more easily hydrogenated to methane than m-HCOO*. The systematic study marks the significance of precise tailoring of the synergistic relationship between oxygen vacancies and basic sites for achieving the desired performance in CO2 methanation. [ABSTRACT FROM AUTHOR]

It was accepted ligands played key role for selective synthesis and catalysis. A novel pyridinyltriazine skeleton ligand, the corresponding catalysts SBA-15@TZP-Ir and SBA-15@TZP-Ru were synthesized and fully characterized by modern methods. The resulting catalysts showed high catalytic activity in selective synthesis of useful substituted perimidines and aminopyrimidines in high yields. Additionally, SBA-15@TZP-Ir and SBA-15@TZP-Ru could be easily recycled for five times for both transformations and preliminary mechanism explorations were conducted to better study these reactions. The mesoporous silica-supported-iridium and ruthenium catalysts (SBA-15@TZP-Ir, SBA-15@TZP-Ru) were synthesized, characterized and showed high catalytic activity in the synthesis of useful substituted perimidines and aminopyrimidines with high yields. [ABSTRACT FROM AUTHOR]

Photothermal catalysis is one of the most promising green catalytic technologies, while distinguishing the effects of hot electrons and local heating remains challenging. Herein, we reported that the actual reaction temperature of photothermal ammonia synthesis over carbon‐supported Ru catalyst can be measured based on Le Chatelier′s principle, enabling the hot‐electron contribution to be quantified. By excluding local heating effects, we established that the activation energy via photothermal catalysis was much lower than that of thermocatalysis (54.9 vs. 126.0 kJ mol−1), stemming from hot‐electron injection lowering the energy barriers for both N2 dissociation and intermediates hydrogenation. Furthermore, hot‐electron injection acted to suppress carbon support methanation, giving the catalyst outstanding operational stability over 1000 h. This work provides new insights into the hot‐electron effects in ammonia synthesis, guiding the design of high‐performance photothermal catalysts. [ABSTRACT FROM AUTHOR]

The utilization of CO2 as a non‐toxic and cheap feedstock for C1 is a desirable route to achieve high value‐added chemicals. In this context, we report a highly efficient ruthenium‐catalyzed semi‐hydrogenation reaction of CO2‐derived ureas. Various alkyl and aryl urea derivatives were successfully hydrogenated to obtain the corresponding recyclable amines and formamides (up to 97 % yield), highlighting the good substrate applicability of this method, which makes this method a sustainable alternative for the hydrogenation of CO2 to formamides in the presence of amines. In the meantime, we have discovered a new pathway that enables rapid hydrogenation of urea derivatives even at lower H2 pressure (<5 bar). This methodology might provide a new insight into the reduction functionalization of CO2 under mild pressure to form new C−N bond. Based on the control experiments and the observed intermediate products, we clarify the mechanism for selective semi‐hydrogenation of ureas. [ABSTRACT FROM AUTHOR]

Glycosyl anomeric radical addition reactions have been well‐explored and proved efficient for the C‐alkyl glycosides synthesis, but multicomponent Domino transformations for the rapid and controllable construction of structurally diversified C‐alkyl glycosides in a single step are still rare. In contrast, we, herein, report a ruthenium(II)‐catalyzed Domino meta‐C−H ethyl glycosylation, enabling the construction of challenging meta‐C‐alkyl glycosides. Our ruthenium(II) catalysis was reflected by the mild reaction condition, exclusive meta‐site selectivity and high levels of anomeric selectivity. In addition, the ruthenium(II)‐catalyzed Domino meta‐C−H glycosylation allowed for the synthesis of versatile 1,2‐trans‐C‐alkyl glycosides with commercially available vinyl arenes, acrylates and easily accessible glycosyl bromides. [ABSTRACT FROM AUTHOR]

Through the catalysis system design of in situ Ru SACs (single atoms) anchored on a rGO/NC two-dimensional interface, we successfully realized the SA-Ru@rGO/NC electrocatalyst with high metal loading density at a relatively low temperature. The largest NH3 yield of 110.1 μg h−1 mgcat−1 and FE of 17.9% were achieved at −0.3 V under ambient conditions. The electronic environment of the catalyst was regulated by the electronic metal–support interaction, and the use of SACs had the advantages of inhibiting the hydrogen evolution reaction (HER) and enhancing N2 adsorption, which effectively improved the performance of electrocatalytic nitrogen fixation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ruthenium olefin metathesis catalyst (C1-H) with a tridentate hemilabile NHC ligand was compared with its methylated derivative (C1-Me). • The kinetic profile, metathesis activity, and decomposition behavior of C1-H and C1-Me were found to differ significantly. • X-ray structure analysis suggests that this difference is due to the remote torsional strain on the NHC ligand. A ruthenium olefin metathesis catalyst (C1-H) bearing a novel NHC ligand tethered by a labile ethoxy-pyridyl arm was synthesized and characterized. The initiation rate, kinetics, metathesis activity, and decomposition behavior were compared with its methylated derivative (C1-Me), showing that these two catalysts vary profoundly. We demonstrate the considerable influence of remote torsional strain on the catalytic activity and decomposition behavior of this ligand class – a feature that can be exploited for related systems. [ABSTRACT FROM AUTHOR]

Ammonia is used as a feedstock in the fertilizer industry and is CO2-free hydrogen (H2) and energy carrier. The Haber-Bosch process industrially used for ammonia synthesis is an energy-intensive process. Therefore, developing such efficient catalysts that can effectively synthesize ammonia at mild reaction conditions is highly required. In this study, efficient 1 wt-% Ru/CeO2/MgO catalysts were fabricated in various Ce/Mg molar ratios. At first, CeO2 was impregnated on MgO, and then these prepared CeO2/MgO were used as support to fabricate 1 wt-% Ru catalysts. Among all the Ru/CeO2/MgO catalysts, the catalysts with Ce/Mg molar ratios 0.1 and 0.3 showed the highest ammonia yields at 400 °C, which was even higher than that attained with pure CeO2 supported Ru catalyst. The measurement of activation energies and NH3, H2, and N2 reaction orders showed that the catalysts with Ce/Mg molar ratios 0.1 and 0.3 had the lowest activation energies and positive values for the H2 order. Moreover, H2-TPR analysis presented a relatively higher value for H2 consumption at lower temperatures indicating these catalysts with higher efficiency for Ru reduction than others. [ABSTRACT FROM AUTHOR]

Sustainable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks is globally sought to replace the Haber–Bosch process. Here, using nitrogen and water as raw materials, a nonthermal plasma catalysis approach is demonstrated as an effective power‐to‐chemicals conversion strategy for ammonia production. By sustaining a highly reactive environment, successful plasma‐catalytic production of NH3 was achieved from the dissociation of N2 and H2O under mild conditions. Plasma‐induced vibrational excitation is found to decrease the N2 and H2O dissociation barriers, with the presence of matched catalysts in the nonthermal plasma discharge reactor contributing significantly to molecular dissociation on the catalyst surface. Density functional theory calculations for the activation energy barrier for the dissociation suggest that ruthenium catalysts supported on magnesium oxide exhibit superior performance over other catalysts in NH3 production by lowering the activation energy for the dissociative adsorption of N2 down to 1.07 eV. The highest production rate, 2.67 mmol gcat.−1 h−1, was obtained using ruthenium catalyst supported on magnesium oxide. This work highlights the potential of nonthermal plasma catalysis for the activation of renewable sources to serve as a new platform for sustainable ammonia production. [ABSTRACT FROM AUTHOR]

The catalysts with platinum-group metals on nanostructured carbons have been a very active field of research, but the studies were mainly limited to Pt and Pd. Here, Ru catalysts based on nitrogen-doped carbon nanotubes (N-CNTs) have been prepared and thoroughly characterized; Ru loading was kept constant (3 wt.%), while the degree of N-doping was varied (from 0 to 4.8 at.%) to evaluate its influence on the state of supported metal. Using the N-CNTs afforded ultrafine Ru particles (<2 nm) and allowed a portion of Ru to be stabilized in an atomic state. The presence of Ru single atoms in Ru/N-CNTs expectedly increased catalytic activity and selectivity in the formic acid decomposition (FAD) but had no effect in catalytic wet air oxidation (CWAO) of phenol, thus arguing against a key role of single-atom catalysis in the latter case. A remarkable difference between these two reactions was also found in regard to catalyst stability. In the course of FAD, no changes in the support or supported species or reaction rate were observed even at a high temperature (150 °C). In CWAO, although 100% conversions were still achievable in repeated runs, the oxidizing environment caused partial destruction of N-CNTs and progressive deactivation of the Ru surface by carbonaceous deposits. These findings add important new knowledge about the properties and applicability of Ru@C nanosystems. [ABSTRACT FROM AUTHOR]

Li–CO2 batteries possess exceptional advantages in using greenhouse gases to provide electrical energy. However, these batteries following Li2CO3-product route usually deliver low output voltage (<2.5 V) and energy efficiency. Besides, Li2CO3-related parasitic reactions can further degrade battery performance. Herein, we introduce a soluble binuclear copper(I) complex as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries. The Li–CO2 battery using the copper(I) complex exhibits a high electromotive voltage up to 3.38 V, an increased output voltage of 3.04 V, and an enlarged discharge capacity of 5846 mAh g−1. And it shows robust cyclability over 400 cycles with additional help of Ru catalyst. We reveal that the copper(I) complex can easily capture CO2 to form a bridged Cu(II)-oxalate adduct. Subsequently reduction of the adduct occurs during discharge. This work innovatively increases the output voltage of Li–CO2 batteries to higher than 3.0 V, paving a promising avenue for the design and regulation of CO2 conversion reactions. Li–CO2 batteries following Li2CO3-product route suffer from low output voltage and severe parasitic reactions. Herein, a soluble binuclear copper(I) complex is introduced as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries, which increases their output voltage to higher than 3.0 V. [ABSTRACT FROM AUTHOR]

The p‐Cymene ruthenium(II) complex is one of the most widely used catalysts in C−H activation. However, enantioselective C−H activation promoted by arene ruthenium(II) complexes has not been realized until recently. The revealed strategies include intramolecular nitrene C−H insertion, the use of chiral transient directing groups, chiral carboxylic acid, relay catalysis, and chiral arene ligands. In this minireview, these advances are summarized and discussed in the hope of spurring further developments. [ABSTRACT FROM AUTHOR]

Nano and single‐atom catalysis open new possibilities of producing green hydrogen (H2) by water electrolysis. However, for the hydrogen evolution reaction (HER) which occurs at a characteristic reaction rate proportional to the potential, the fast generation of H2 nanobubbles at atomic‐scale interfaces often leads to the blockage of active sites. Herein, a nanoscale grade‐separation strategy is proposed to tackle mass‐transport problem by utilizing ordered three‐dimensional (3d) interconnected sub‐5 nm pores. The results reveal that 3d criss‐crossing mesopores with grade separation allow efficient diffusion of H2 bubbles along the interconnected channels. After the support of ultrafine ruthenium (Ru), the 3d mesopores are on a superior level to two‐dimensional system at maximizing the catalyst performance and the obtained Ru catalyst outperforms most of the other HER catalysts. This work provides a potential route to fine‐tuning few‐nanometer mass transport during water electrolysis. [ABSTRACT FROM AUTHOR]

Alkene metathesis catalyzed by enantiopure metal alkylidene complexes enables exceptionally versatile strategies to products with configurationally‐defined stereocenters. Desymmetrization processes thereby provide reliable stereoselective routes to aliphatic structures, while the differentiation of aromatic stereogenic units remained an outstanding challenge. Herein, we describe the feasibility of alkene metathesis to catalytically control stereogenic axes by traceless arene formation. Stereodynamic trienes are selectively converted into corresponding binaphthalene atropisomers upon exposure to a chiral molybdenum catalyst. Remarkably, stereoselective arene‐forming metathesis allows enantioselectivities of up to 98 : 2 e.r. and excellent yields. As the disconnection of each bond of an aromatic target is retrosynthetically conceivable, it is anticipated that forging arenes by means of stereoselective metathesis will enable versatile approaches for the synthesis of a broad range of molecular topologies with precisely defined configuration. [ABSTRACT FROM AUTHOR]

• Low-cost Ru nanoclusters (NCs)/Mo 2 C is designed for enhanced HOR catalysis. • Modulation of dual active sites within a Ru cluster is achieved for the first time. • The adsorption of H*/OH* is balanced by regulating d-band centers of Ru NCs. • Ru/Mo 2 C has excellent HOR catalytic activity, long-term stability and CO tolerance. Designing non-Pt metal electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is highly desirable to address the unsustainable use of high-cost and scarce Pt. Although challenging, this study introduces an ultrasmall Ruthenium nanoclusters (Ru NCs)-based electrocatalyst with dual active sites for efficient alkaline HOR. While the selection of Ru is based on its cost-effectiveness, smaller atomic number, and comparable physicochemical properties to Pt, the employment of Mo 2 C as the support is mainly for establishing strong electronic metal-support interaction (EMSI) within the catalyst. This EMSI effect facilitates significant charge redistribution and the formation of efficient dual-active sites within a single Ru NC. Experiments and simulations confirm that the EMSI effect modulates the d-band centers of the Ru NCs at both H-adsorption and OH-adsorption sites, endowing the Ru/Mo 2 C catalyst with up to 16.6 times and 29.7 times higher mass activity than commercial Pt/C and Ru/C, respectively, as well as enhanced long-term stability and CO resistance. This work provides a paradigm in designing non-Pt metal NCs for alkaline HOR electrocatalysis, underscoring the significance of adjusting the EMSI effect for performance escalation of HOR catalysis. [ABSTRACT FROM AUTHOR]

Quinazolines are synthesized by acceptorless dehydrogenative coupling of 2-aminobenzyl alcohols with benzonitriles utilizing Ru(II)- p -cymene catalysts bearing ferrocene acylthiourea (Fc-Tu) ligands. [Display omitted] • Synthesis and characterization of Ru(II)- p -cymene complex containing ferrocene acylthiourea ligand. • Complexes were evaluated for catalytic activity in the acceptorless dehydrogenative coupling (ADC) process to produce quinazolines. • The substrate scope was extended to aromatic, aliphatic and heterocyclic substituents. • All the catalytic experiments exhibited good to moderate yields, with hydrogen and water as the by-products. The catalytic activity of Ru(II)- p -cymene complexes containing ferrocene acylthiourea (Fc-Tu) ligands was investigated towards the synthesis of quinazolines via acceptorless dehydrogenative coupling of 2-aminobenzyl alcohols with benzonitriles. A series of Ru(II)- p -cymene complexes (1 – 4) containing Fc-Tu ligands (L 1 -L 4) was synthesized and characterized. From the single crystal X-ray crystallographic studies, the molecular structures of ligand L 4 and complex 1 were confirmed. The influence of electronic effects of the ligands on the catalytic activity of their complexes was studied. 2-Aminobenzyl alcohol and benzonitrile were used as model substrates for the optimization reactions, and the scope of the catalytic system was extended to a diverse range of substrates containing both electron-donating and –withdrawing groups. The mechanism was proposed for the synthesis of quinazolines. Overall, the synthesis of quinazolines was accomplished with good to moderate yields (up to 78 %), with hydrogen and water as only by-products. [ABSTRACT FROM AUTHOR]

Sustainable sources are key to future chemicals production. Microalgae are promising resources as they fixate carbon dioxide to organic molecules by photosynthesis. Thereby they produce unsaturated fatty acids as established raw materials for the industrial production of chemical building blocks. Although these renewable feedstocks are generated inside cells, their catalytic upgrading to useful products requires in vitro transformations. A synthetic catalysis inside photoautotrophic cells has remained elusive. Here we show that a catalytic conversion of renewable substrates can be realized directly inside living microalgae. Organometallic catalysts remain active inside the cells, enabling in vivo catalytic olefin metathesis as new‐to‐nature transformation. Stored lipids are converted to long‐chain dicarboxylates as valuable building blocks for polymers. This is a key step towards the long‐term goal of producing desired renewable chemicals in microalgae as living "cellular factories". [ABSTRACT FROM AUTHOR]

The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2 is reported. The ditopic bridging ligand L1∩L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post‐functionalization strategy based on Diels‐Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7‐phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono‐ and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV‐vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti‐[(L1∩L2){Ru(bpy)2}][PF6]2 and the bimetallic analogue syn‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic AuI/RuII complexes syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2 are both active catalysts in the P‐arylation of aryldiazonium salts promoted by visible light with H‐phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts. [ABSTRACT FROM AUTHOR]

Highlights: A multicomponent Co@CNTs|Ru catalyst has been rationally designed, in which Co nanoparticles are in-situ confined inside CNTs while trace Ru loading is uniformly deposited on their exterior walls. Co and Ru nanoparticles spatially confined by the inner and outer surface of CNTs, respectively, would induce charge redistribution and a synergistic electron coupling. Co@CNTs|Ru catalyst exhibits an unprecedented hydrogen evolution reaction (HER) activity in all pH-range, representing a new record among all the previously reported HER catalysts. Exploring highly active but inexpensive electrocatalysts for the hydrogen evolution reaction (HER) is of critical importance for hydrogen production from electrochemical water splitting. Herein, we report a multicomponent catalyst with exceptional activity and durability for HER, in which cobalt nanoparticles were in-situ confined inside bamboo-like carbon nanotubes (CNTs) while ultralow ruthenium loading (~ 2.6 µg per electrode area ~ cm−2) is uniformly deposited on their exterior walls (Co@CNTsǀRu). The atomic-scale structural investigations and theoretical calculations indicate that the confined inner Co and loaded outer Ru would induce charge redistribution and a synergistic electron coupling, not only optimizing the adsorption energy of H intermediates (ΔGH*) but also facilitating the electron/mass transfer. The as-developed Co@CNTsǀRu composite catalyst requires overpotentials of only 10, 32, and 63 mV to afford a current density of 10 mA cm−2 in alkaline, acidic and neutral media, respectively, representing top-level catalytic activity among all reported HER catalysts. The current work may open a new insight into the rational design of carbon-supported metal catalysts for practical applications. [ABSTRACT FROM AUTHOR]

In recent years, visible-light photoredox catalysis has become a widely used synthetic method. Photoredox-catalyzed Meerwein reaction of styrenes in the presence of 2,2,2-trifluoroethanol as a nucleophile afforded the target aryl trifluoroethoxylation products in moderate yields 32–53%. The best results were achieved using [Ru(bpy)3](PF6)2 as a catalyst in the presence of Na2HPO4 in acetonitrile. [ABSTRACT FROM AUTHOR]

Organic photoredox catalysts with a long excited-state lifetime have emerged as promising alternatives to transition-metal-complex photocatalysts. This paper explains the effectiveness of using long-lifetime photoredox catalysts for organic transformations, focusing on the structures and photophysics that enable long excited-state lifetimes. The electrochemical potentials of the reported organic, long-lifetime photocatalysts are compiled and compared with those of the representative Ir(III)- and Ru(II)-based catalysts. This paper closes by providing recent demonstrations of the synthetic utility of the organic catalysts. 1 Introduction 2 Molecular Structure and Photophysics 3 Photoredox Catalysis Performance 4 Catalysis Mediated by Long-Lifetime Organic Photocatalysts 4.1 Photoredox Catalytic Generation of a Radical Species and its Addition to Alkenes 4.2 Photoredox Catalytic Generation of a Radical Species and its Addition to Arenes 4.3 Photoredox Catalytic Generation of a Radical Species and its Addition to Imines 4.4 Photoredox Catalytic Generation of a Radical Species and its Addition to Substrates Having C≡X Bonds (X=C, N) 4.5 Photoredox Catalytic Generation of a Radical Species and its Bond Formation with Transition Metals 4.6 Miscellaneous Reactions of Radical Species Generated by Photoredox Catalysis 5 Conclusions [ABSTRACT FROM AUTHOR]

Ruthenium(II) complexes with the general formula TpRu(L)(NCMe)Ph (Tp = hydrido(trispyrazolyl)borate, L = CO, PMe3, P(OCH2)3CEt, P(pyr)3, P(OCH2)2(O)CCH3) have previously been shown to catalyze arene alkylation via Ru-mediated arene C–H activation including the conversion of benzene and ethylene to ethylbenzene. Previous studies have suggested that the catalytic performance of these TpRu(II) catalysts increases with reduced electron-density at the Ru center. Herein, three new structurally related Ru(II) complexes are synthesized, characterized, and studied for possible catalytic benzene ethylation. TpRu(NO)Ph2 exhibited low stability due to the facile elimination of biphenyl. The Ru(II) complex (TpBr3)Ru(NCMe)(P(OCH2)3CEt)Ph (TpBr3 = hydridotris(3,4,5-tribromopyrazol-1-yl)borate) showed no catalytic activity for the conversion of benzene and ethylene to ethylbenzene, likely due to the steric bulk introduced by the bromine substituents. (Ttz)Ru(NCMe)(P(OCH2)3CEt)Ph (Ttz = hydridotris(1,2,4-triazol-1-yl)borate) catalyzed approximately 150 turnover numbers (TONs) of ethylbenzene at 120 °C in the presence of Lewis acid additives. Here, we compare the activity and features of catalysis using (Ttz)Ru(NCMe)(P(OCH2)3CEt)Ph to previously reported catalysis based on TpRu(L)(NCMe)Ph catalyst precursors. [ABSTRACT FROM AUTHOR]

A number of natural and biologically active compounds can be synthesized via ruthenium catalysis. As ruthenium is the cheapest noble metal and can be extensively used to synthesize a variety of catalysts, particular attention has been made in the synthesis of chemotherapeutic agents, polymers, biopolymers and agrochemicals through this catalysis. Ruthenium-based catalysts are well famous because of their broad range of functional group, air and moisture tolerance. Different organic reactions such as alkylation, arylation, isomerization and olefin metathesis are efficiently carried out in the presence of these catalysts within short reaction time. In 1992, Robert H. Grubbs first time introduced ruthenium-based catalyst, known as Grubbs first-generation catalyst (G-1) to carry out olefin metathesis effectively. Later on, Grubbs second-generation G-2, third-generation catalyst G-3 and Hoveyda–Grubbs catalysts such as HG-1 and HG-2 were also obtained by changing different ligands with ruthenium. In this review, recent advances in the synthesis of ruthenium-based Grubbs catalysts and their usage in natural product synthesis via olefin metathesis are discussed briefly. [ABSTRACT FROM AUTHOR]

[Display omitted] • Incorporating Ru improves the catalytic capability and durability of both Ni and Co catalysts. • Ru modification decreases the dehydrogenation barriers of CH x * on the NiRu metal surface. • Ru-doped Co catalysts alter the main intermediates for CH 4 dehydrogenation and hence enhance carbon resistance. In this work, Ru is incorporated into Ni/Co to synthesize novel Al 2 O 3 -supported Ni-Ru/Co-Ru bimetallic catalysts. Tests verify their enhanced catalytic capability and durability and also reveal how each catalyst is deactivated. SEM and EDS results indicate that nanoparticle agglomeration on Ni-based surface triggers deactivation, and TG and XPS results suggest carbon deposition is fatal to Co-based catalysts. Implementing Ru effectively enhances catalytic activity and durability. To gain insight into the promoting effect of Ru, quantum mechanical methods are utilized to investigate the shifts in activation energies (E a) in CH x * dehydrogenation processes on (1 1 1) surfaces. For the Ni catalyst, DFT calculations indicate that adding Ru decreases E a yet does not change the determining step. In contrast, adding Ru on the Co surface changes the major intermediates from CH* to CH 2 *, which inhibits further dehydrogenation, and hence mitigates carbon deposition to preserve the catalytic activity of the surface. [ABSTRACT FROM AUTHOR]

Bio-based polymers are materials of high interest given the harmful environmental impact that involves the use of non-biodegradable fossil products for industrial applications. These materials are also particularly interesting as bio-based ligands for the preparation of metal nanoparticles (MNPs), employed as catalysts for the synthesis of high value chemicals. In the present study, Ru (0) and Rh(0) Metal Nanoparticles supported on Sodium Carboxymethyl cellulose (MNP(0)s-CMCNa) were prepared by simply mixing RhCl 3 x3H 2 O or RuCl 3 with an aqueous solution of CMCNa, followed by NaBH 4 reduction. The formation of MNP(0)s-CMCNa was confirmed by FT-IR and XRD, and their size estimated to be around 1.5 and 2.2 nm by TEM analysis. MNP(0)s-CMCNa were employed for the hydrogenation of (E)-cinnamic aldehyde, furfural and levulinic acid. Hydrogenation experiments revealed that CMCNa is an excellent ligand for the stabilization of Rh(0) and Ru(0) nanoparticles allowing to obtain high conversions (>90 %) and selectivities (>98 %) with all substrates tested. Easy recovery by liquid/liquid extraction allowed to separate the catalyst from the reaction products, and recycling experiments demonstrated that MNPs-CS were highly efficiency up to three times in best hydrogenation conditions. [Display omitted] • Carboxymethyl cellulose has been successfully used as support for metal nanoparticles formation. • An easy and mild method to prepare Ru(0) and Rh(0) nanoparticles has been developed. • Ru(0) and Rh(0) – CMC catalysts have been applied for the hydrogenation of cinnamaldehyde, furfural and levulinic acid. [ABSTRACT FROM AUTHOR]

Creating useful chemicals or fuels from CO 2 is one of the most promising ways to reach carbon neutral. In this work, through the formation of Lewis acid sites, a string of boron-atom-coordinated Ru single-atom catalysts (SACs), namely RuB x N 4-x @TiN (x=0–4), were constructed, and their CO 2 reduction reaction (CO 2 RR) was systematically studied. The results show that o -RuB 2 N 2 @TiN, p -RuB 2 N 2 @TiN, and RuB 3 N 1 @TiN are able to efficiently inhibit the competitive hydrogen evolution reaction (HER) and activate CO 2 , with a potential-determining step lower than 0.7 eV and high selectivity for CH 4 generation. This work shows that the synergistic effect of B and Ru atoms are able to effectively improve the catalytic activity, which is expected to offer a possible tactic for the sensible creation of effective CO 2 RR catalysts. • Boron doped Ru single-atom catalysts, were constructed for investigating the reaction mechanism of CO 2 reduction. • Synergistic effect of B and Ru atoms effectively improves catalytic activity for CO 2 reduction. • The RuB x N 4- x @TiN (x=2–3) can activate CO 2 with low potential-determining step and high selectivity for CH 4 generation. [ABSTRACT FROM AUTHOR]

Unequivocal assignment of rate-limiting steps in supramolecular photocatalysts is of utmost importance to rationally optimize photocatalytic activity. By spectroscopic and catalytic analysis of a series of three structurally similar [(tbbpy)2Ru-BL-Rh(Cp*)Cl]3+ photocatalysts just differing in the central part (alkynyl, triazole or phenazine) of the bridging ligand (BL) we are able to derive design strategies for improved photocatalytic activity of this class of compounds (tbbpy = 4,4´-tert-butyl-2,2´-bipyridine, Cp* = pentamethylcyclopentadienyl). Most importantly, not the rate of the transfer of the first electron towards the RhIII center but rather the rate at which a two-fold reduced RhI species is generated can directly be correlated with the observed photocatalytic formation of NADH from NAD+. Interestingly, the complex which exhibits the fastest intramolecular electron transfer kinetics for the first electron is not the one that allows the fastest photocatalysis. With the photocatalytically most efficient alkynyl linked system, it is even possible to overcome the rate of thermal NADH formation by avoiding the rate-determining β-hydride elimination step. Moreover, for this photocatalyst loss of the alkynyl functionality under photocatalytic conditions is identified as an important deactivation pathway. Although multinuclear, supramolecular photocatalysts show promise in their ability to separate the processes required for lightdriven energy production into light absorption, charge separation and fuel production by individual parts of the molecule, mechanistic understanding of the performance limiting processes are lacking. Here the authors synthesize two new dinuclear catalysts and compare them to a benchmark through detailed spectroscopic studies, obtaining significant chemical insight. [ABSTRACT FROM AUTHOR]