Search

Transition metal catalysts supported on topological insulators are predicted to show improved catalytic properties due to the presence of topological surface states, which may float up to the catalysts and provide robust electron transfer. However, experimental studies of surface structures and corresponding catalytic properties of transition metal/topological insulator heterostructures have not been demonstrated so far. Here, we report the structures, chemical states, and adsorption behaviors of two conventional transition metal catalysts, Pt and Pd, on the surface of Bi2Se3, a common topological insulator material. We reveal that Pt forms nanoparticles on the Bi2Se3 surface. Moreover, the interaction between Pt and surface Se is observed. Furthermore, thermal dosing of O2 onto the Pt/Bi2Se3 heterostructure leads to no oxygen adsorption. Detailed scanning tunneling microscopy study indicates that Pt transforms into PtSe2 after the thermal process, thus preventing O2 from adsorption. For another transition metal Pd, it exhibits approximate layer-island growth on Bi2Se3, and Pd–Se interaction is also observed. Our work provides significant insights into the behaviors of transition metals on top of a common topological insulator material and will assist in the future design of catalysts built with topological materials. [ABSTRACT FROM AUTHOR]

Transition metal catalysts supported on topological insulators are predicted to show improved catalytic properties due to the presence of topological surface states, which may float up to the catalysts and provide robust electron transfer. However, experimental studies of surface structures and corresponding catalytic properties of transition metal/topological insulator heterostructures have not been demonstrated so far. Here, we report the structures, chemical states, and adsorption behaviors of two conventional transition metal catalysts, Pt and Pd, on the surface of Bi2Se3, a common topological insulator material. We reveal that Pt forms nanoparticles on the Bi2Se3 surface. Moreover, the interaction between Pt and surface Se is observed. Furthermore, thermal dosing of O2 onto the Pt/Bi2Se3 heterostructure leads to no oxygen adsorption. Detailed scanning tunneling microscopy study indicates that Pt transforms into PtSe2 after the thermal process, thus preventing O2 from adsorption. For another transition metal Pd, it exhibits approximate layer-island growth on Bi2Se3, and Pd–Se interaction is also observed. Our work provides significant insights into the behaviors of transition metals on top of a common topological insulator material and will assist in the future design of catalysts built with topological materials. [ABSTRACT FROM AUTHOR]

A nitrogen K-edge x-ray absorption near-edge structure (XANES) survey is presented for tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:2‴,3‴-j]phenazine (tpphz)-bridged bimetallic assemblies that couple chromophore and catalyst transition metal complexes for light driven catalysis, as well as their individual molecular constituents. We demonstrate the high N site sensitivity of the N pre-edge XANES features, which are energetically well-separated for the phenazine bridge N atoms and for the individual metal-bound N atoms of the inner coordination sphere ligands. By comparison with the time-dependent density functional theory calculated spectra, we determine the origins of these distinguishable spectral features. We find that metal coordination generates large shifts toward higher energy for the metal-bound N atoms, with increasing shift for 3d < 4d < 5d metal bonding. This is attributed to increasing ligand-to-metal σ donation that increases the effective charge of the bound N atoms and stabilizes the N 1s core electrons. In contrast, the phenazine bridge N pre-edge peak is found at a lower energy due to stabilization of the low energy electron accepting orbital localized on the phenazine motif. While no sensitivity to ground state electronic coupling between the individual molecular subunits was observed, the spectra are sensitive to structural distortions of the tpphz bridge. These results demonstrate N K-edge XANES as a local probe of electronic structure in large bridging ligand motifs, able to distinctly investigate the ligand-centered orbitals involved in metal-to-ligand and ligand-to-ligand electron transfer following light absorption. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Dalton Transactions: An International Journal of Inorganic Chemistry," published by The Royal Society of Chemistry. It includes articles on various topics such as electrochemically driven physical properties of solid-state materials, Keplerate polyoxometalate compounds, and the development of homogeneous first-row early transition metal catalysts. The journal features research papers, communications, and perspectives on cutting-edge advancements in the field of inorganic chemistry. [Extracted from the article]

The oxygen reduction reaction (ORR) remains an important fixture in biological and synthetic systems for energy conversion and chemical functionalization. Late transition metals continue to dominate in the development of new catalyst systems, inspired by well-characterized metallocofactors and prior successes. By comparison, metals to the left of Fe on the periodic table are relatively understudied for the ORR. This Frontier article summarizes advancements related to the use of Mn, Cr, and V in homogeneous catalyst systems for the ORR and discusses the implications of these results for the development of catalyst systems from these metals and those earlier in the transition metal series. [ABSTRACT FROM AUTHOR]

Borylation of haloarenes is one of the most important methodologies to synthesize borylated arenes. Generally, borylation of haloarenes occurs smoothly at the sterically less hindered para or meta position by the use of a transition metal catalyst or a photoredox catalyst or under basic conditions. This study reports on the ortho -specific and chemoselective borylation of ortho -iodoarene possessing carboxamide under visible-light irradiation. When a haloarene containing both C–I and C–X bonds is employed as a substrate, another C–X bond (not ortho) remains intact during the reaction. Mechanistic studies revealed that the key to the success of this reaction is the generation of a diboron-bridged five-membered ring as a transition state, in which the diboron-bridged five-membered ring and the benzene ring in the transition state are perpendicular to each other, owing to steric repulsion by the iodine atom at the ortho position. This chemoselectivity is suitable for the synthesis of borylated building blocks. [ABSTRACT FROM AUTHOR]

Developing high-efficiency, high-stability, and low-cost deoxygenation and hydrocracking catalysts could be considered one of the most significant breakthroughs in catalytic hydroprocessing. The present study utilized aluminophosphate (AlPO4-18), a zeolite-like molecular sieve, as catalyst support for producing carbon-coated β-Mo2C, Ni3C, and WC nanoparticles. The synthesis used an incipient wetness impregnation followed by a temperature-programmed reduction-carburization approach which involved cracking a hydrocarbon gas, propane, in a hydrogen environment. The synthesis parameters were a 1:7 propane/hydrogen reductive-carburizing gas stream, 15 wt.% metal loading, an 800 °C carburization temperature ramped-up at a heating rate of 10 °C min−1, a 2-h holding time, and a 1-h holding time in hydrogen. The synthesized catalysts were characterized using thermogravimetry mass spectroscopy/temperature-programmed oxidation (TPO TG-MS), nitrogen physisorption at 77 K, X-ray diffraction (XRD), and transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM EDS). TPO TG-MS, nitrogen physisorption, TEM, and XRD characterization results proved that atomic carbon was successfully incorporated into the lattice interstitials, resulting in thermally stable, well-dispersed, crystalline and mesoporous β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18 nanoparticles. XRD analysis showed structural evolution during reduction-carburization, with average crystallite sizes of metal-containing particles of 8.2–9.22, 6.64–8.50, and 6.03–7.56 nm for β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18, respectively. These values did not significantly deviate from high-resolution TEM analysis. The surface areas of the nanoparticles were categorized in decreasing order as WC/AlPO4-18 > Ni3C/AlPO4-18 > β-Mo2C/AlPO4-18, with values of 193.79, 169.05, and 66.57 m2 g−1, respectively. In conclusion, these carbon-coated metal carbide nanoparticles with excellent thermal, structural, microscopic, and textural properties can be viable alternatives to noble metal catalysts for producing bio-jet fuel using the hydroprocessing pathway. [ABSTRACT FROM AUTHOR]

The growing global population needs energy from clean and renewable resources to meet present and future demands. Ideally, green hydrogen is commonly considered the key to overcoming the energy problem and the future energy standard. One of the most promising technologies for the development of the hydrogen economy is electrolysis water splitting (WS) hydrogen (H 2) production; nevertheless, developing highly efficient environmentally sustainable electrocatalysts remains a serious issue for this technology. Transition metals (TMs) have achieved substantial progress in recent years, as a structural-based electrocatalyst developing especially noteworthy attention for the hydrogen evolution process (HER). These features have been proven to constitute the perfect electrocatalyst due to their advantages such as low cost, efficiency, stability, a large number of active sites, and great surface. This comprehensive review explains TMs-based chalcogenides and particular structural arrangements of multi-dimensional (1D, 2D, and 3D) electrocatalysts on different substrates for WS hydrogen production. The reaction process, the importance of the electrocatalyst, the advantages of the structural materials, and the efficiency that fluctuates with phase dimensions, have been investigated. Finally, the present issues and prospects of structural materials for WS were investigated in terms of HER and the perspective of this field was presented. [Display omitted] • Review of recent trends in electrochemical water splitting-H 2 Production using Transition Metals (TMs). • Role of different functional groups, morphology (1D, 2D & 3D) on electrochemical water splitting. • Design strategies for constructing TMs/nanostructures. • Comparing different catalyst architectures for optimal HER efficiency. [ABSTRACT FROM AUTHOR]

To access degradable polyolefin plastic, non‐alternating copolymerization of ethylene (E) and carbon monoxide (CO) for producing polyethylene (PE) with in‐chain ketones is particularly appealing; however, it still presents significant challenges such as molecular weight modulation (hydrogen response) and chain endgroup control (functional terminal). In this study, we achieved hydrogen‐controlled E/CO non‐alternating copolymerization using late transition metal catalysts. This process results in linear PEs containing the desired non‐alternating in‐chain keto groups (1.0–9.3 mol %) and with tunable molecular weights ranging from 43 to 195 kDa. In this reaction, H2 serves as a chain transfer agent, modulating the polymer's molecular weight, forming unique aldehyde endgroups and eliminating usual olefinic endgroups; CO undergoes non‐alternating insertion into the PE chain, resulting in a strictly non‐alternating structure (>99 %) for the keto‐PE. The dispersed incorporation of in‐chain keto groups retains bulk properties of PE and makes PE susceptible to photodegradation, which produces significantly lower molecular weight polymers and oligomers with unambiguous vinyl and acetyl terminals. [ABSTRACT FROM AUTHOR]

Heterocyclic fluoroalkylation is initiated through a photochemical reaction involving an electron donor–acceptor complex. The reaction proceeds smoothly without requiring a photocatalyst, transition metal catalyst or additional oxidant. Through extensive experiments, we optimised the heterocyclic fluoroalkylation method and confirmed its versatility and effectiveness on various substrates. The process synthesises fluoroalkylated quinoxalinones and indolones with high efficiency and was successfully extended to gram‐scale applications, highlighting its practical utility. Detailed mechanistic analyses, supported by density functional theory calculations elucidated the role of the electron donor–acceptor complexes and deciphered the distinct radical chain reaction mechanism inherent in the halogen‐atom transfer pathway. Given the importance of fluoroalkyl groups in pharmaceuticals, this simple and efficient method promises substantial applications in medicinal chemistry and materials science. [ABSTRACT FROM AUTHOR]

Aqueous oxidative deconstruction of low-density polyethylene (LDPE) was investigated using homogeneous first-row transition metal catalysts under mild conditions (130–150 °C and ≤100 PSI oxygen pressure). Oxidation of LDPE resulted in high yields of low molecular weight carboxylic acids (up to 75% yield as determined by carbon balance). Aqueous processing is well-suited for biological conversion of the breakdown products. [ABSTRACT FROM AUTHOR]

The modification of molybdenum carbide catalysts by another transition metal has raised an increasing research interest due to the significant improvement of catalyst activity in hydrodeoxygenation of lignin derivatives. At par with the commonly used Co and Ni that add a strong hydrogenation functionality, it was found that the addition of the more oxophilic W restricts ring hydrogenation while allowing the deoxygenation of oxygenated compounds and thus yielding higher selectivity toward the formation of non‐oxygenated aromatic compounds. The coexistence of Mo2C with W2C along with metallic W altered the electronic properties of Mo2C which resulted in an increase of catalyst active site density and facilitated further total eugenol deoxygenation. Propyl‐benzene selectivity of up to 83 % was reached at close to 100 % eugenol conversion. These findings will allow a better overview of the effect of different metal phases of mixed carbides on the catalyst performance and raise the prospect of optimizing catalyst design for a hydrodeoxygenation processing of lignin depolymerization products. [ABSTRACT FROM AUTHOR]

Highly efficient novel electrocatalysts for hydrogen/oxygen production are urgently required, for noble metal‐based catalysts substitution. Cobalt phosphides have shown great potential for serving as bifunctional catalysts, owing to the cost effectiveness and high conductivity. However, the water splitting ability of them is still not comparative with commercial noble counterparts. In this work, we reported a Br‐induced strategy, to obtain an ultra‐hydrophilic isostructural Br0.036─Co1.085P@NF catalyst by a gas‐solid reaction method. As a typical halogen element, the introduction of Br can greatly enhance the surficial hydrophilicity and thus further impart ideal adsorption ability for water molecules. Meanwhile, the electronic structure could be regulated to further induce the generation of isostructural cobalt phosphides (CoP/Co2P). As a result, the contact angle of Br0.036─Co1.085P@NF catalysts nearly cannot be caught owing to the ultra‐hydrophilicity. It is also confirmed that, the d‐band center of Co shows apparent negative shift after Br introduction, which reduces the adsorption energy of oxygen‐containing intermediates thereby facilitating the desorption process. Besides, the introduction of Br can also reduce the barrier of O2 formation, show more favorable dynamic behaviors. This work proved the accessibility for an effective design strategy on halogen‐induced isostructural transition metal phosphides catalysts for high‐performance overall water splitting. [ABSTRACT FROM AUTHOR]

Merging heterogeneous catalysis with one-pot tandem reactions serves as a key foundation for practical and sustainable chemistry. Herein, via rational design, porous graphite-phase carbon nitride (porous g-C3N4) was facilely synthesized via a soft template method. Compared to bulk g-C3N4, the larger specific surface area, excellent visible light response capability, and faster electron–hole migration rate enable porous g-C3N4 to exhibit outstanding catalytic performance in the visible light-induced one pot alcohol oxidation–Wittig tandem reactions. This protocol circumvents the use of expensive transition metal catalysts and toxic oxidizing agents, establishing a green and efficient system that facilitates the synthesis of α,β-unsaturated esters. Potentially, g-C3N4 emerges as a promising alternative to noble metal photocatalysts, thereby broadening the horizons of photocatalysis. [ABSTRACT FROM AUTHOR]

As the hydrogen source of carbon-free fuel cells, the key to realize the green and low-energy decomposition hydrogen production process is to select materials with excellent catalytic performance for ammonia dehydrogenation. In this study, the rare earth element lanthanum (La) was doped onto the surface of Al 2 O 3 by the impregnation method. The aforementioned material was subsequently used as a new material for the synthesis of single metal Co catalysts that catalyzed ammonia decomposition. Various characterization techniques (XRD, HRTEM, N 2 physical adsorption-desorption, ICP, XPS, SEM, H 2 -TPR) were employed to investigate the relationship between the structure and performance of Co/La–Al 2 O 3 catalysts. The findings indicated that the 10Co/La(5)-Al 2 O 3 catalyst was the most active. Under the conditions of 550 °C and 9000 mL h−1·g cat −1, the conversion of ammonia reached 90 %, and the yield of hydrogen reached 8.9 mmol·g cat −1·min−1. A perovskite-type metal oxide layer of LaAlO 3 was generated on the surface of Al 2 O 3 support after doping the appropriate amount of lanthanum (5 %), which directly affects the catalytic performance of the catalyst. The small amount of LaAlO 3 optimized the strong interaction between the metal Co and the supports, thereby enhancing catalytic performance. While stabilizing the active component Co, XPS and H 2 -TPR also implied that the presence of La could enhance the electron transfer between the support and Co, as well as facilitate the desorption of nitrogen and hydrogen products, therefore, the low temperature activity of Co/La–Al 2 O 3 catalyst can be improved. The ammonia decomposition efficiency of the catalyst doped with 5 % wt La was much higher than that of the catalyst without La incorporation. The simple modified support developed by us, which loads a monoatomic Co catalyst, provides a new approach for the development of high-activity transition metal catalysts. [ABSTRACT FROM AUTHOR]

Solid supported catalysts have several synthetic applications. Herein, finely ground eggshells were used as a solid support for the preparation of transition metal (Ni, Zn, Cu, Sn and Co) based catalysts to synthesize 2,4-dinitrophenylhydrazone (3) and dihydropyrimidinones (7 and 8). The effect of catalyst load, time and temperature on product yield was studied. Box Behnken Model was employed, and three predictors named catalyst amount (A), reaction time (B), and reaction temperature (C) were used to find the correlation of the predictors with the yield. Second order polynomial equation was used to estimate the effects of these factors. According to the statistical model, about 12% increase in yield was observed as a result of one-unit increase in reaction time while all other terms were kept constant. The values of S (18.1616) and R2 (71.2%) indicate that the statistical model gave an adequate fit to data. Quadratic model for the response surface was used for the analysis of variance (ANOVA) results, the larger F-values, and smaller p-values indicated that the predictors are in good agreement. The linear model terms of predictors were found to be significantly effective for yield (P < 0.05). The response surface and contour plots were also in agreement with the predicted model. [ABSTRACT FROM AUTHOR]

Ammonia borane is widely recognized as a reliable source of hydrogen. However, for efficiently generate hydrogen from ammonia borane, the use of appropriate catalysts is necessary. Transition metal catalysts, significantly enhance the hydrogen production. In our study, we focused on synthesizing a catalyst, Ru-Imine@Al 2 O 3 , by incorporating ruthenium-imine onto the surface of alumina in an ethanoic solution. We conducted this synthesis under ambient conditions. We employed advanced analytical techniques to characterize it. To better understand the structure and composition of catalyst. Notably, this is the first time that Ru-Imine and Ru-Imine@Al 2 O 3 have been used for dehydrogenation of ammonia borane. During our experiments, we found that the Ru-Imine@Al 2 O 3 catalyst exhibited excellent activity in the dehydrogenation process of ammonia borane, releasing hydrogen. We tested different levels of Ru-Imine usage and observed the best performance with 10 % Ru-Imine complex in a 10 mg catalyst. Under these conditions, the catalyst produced 19531 mL H 2 gcat.−1min−1, at 30.0 ± 1 °C. the catalytic activity of 100 % Ru-Imine was also tested under the specified conditions and produced 14183 mL H 2 gcat.−1min−1. To gain further insights into the reaction, we thoroughly determined the kinetics and proposed a mechanism for the dehydrogenation process. Our findings revealed that Ru-Imine@Al 2 O 3 catalyzed dehydrogenation of ammonia borane exhibited a lower activation energy (Ea) of 21.9 kJ mol−1. This implies that the reaction can proceed more easily and efficiently with the presence of the catalyst. Furthermore, we assessed the reusability of the catalyst and found that it demonstrated excellent performance even after eight cycles with 100 % conversion of ammonia borane. This highlights the potential of the Ru-Imine@Al 2 O 3 catalyst for repeated use without significant degradation in its activity. These findings contribute to the advancing of hydrogen generation technologies and offer promising prospects for utilizing ammonia borane as a hydrogen source. [Display omitted] • Ru-Im@Al 2 O 3 catalyst developed to enhance H 2 evolution from NH 3 BH 3 dehydrogenation. • Alumina effect, enhanced the catalytic activity with 19531 mL H 2 g−1 cat.min−1. • Kinetic studies and suggested mechanism were clearly determined for this reaction. • Ru-Im@Al 2 O 3 catalyzed hydrolysis achieved low activation energy of 21.9 kJmol-1. • Ru-Im@Al 2 O 3 displayed high stability of 100 % conversion even after the 8th run. [ABSTRACT FROM AUTHOR]

Hydrogen gas and its production from renewable power sources will be an important part of decreasing global reliance on fossil fuels and developing a sustainable energy economy. Efficient electrocatalysis, however, relies on the delivery of both protons and electrons; ideally in a concerted fashion to avoid high energy intermediates, prevent charge build‐up, and circumvent large kinetic barriers. While this can be achieved using ligand design in homogenous molecular transition metal catalysts (specifically incorporating proton shuttles in the secondary coordination sphere), heterogeneous systems are more desirable from an industrial perspective due to their ease of use and enhanced durability. Supporting transition metal catalysts on electrode surfaces is therefore a promising approach for developing next generation electrocatalysts that retain molecular level control in interfacial environments. This review will first cover key design principles from natural systems, such as hydrogenase enzymes, and then survey some representative examples of synthetic homogeneous hydrogen evolution electrocatalysts that incorporate these important features. We will then discuss transition metal species that have been supported on electrode materials, with a focus on recent advances in the field, and the major challenges that remain. [ABSTRACT FROM AUTHOR]

Herein, we report a general and green protocol for the anti-dihydroxylation of unactivated alkenes. Combining H2O2 and acetic acid at 50 °C results in the formation of peroxyacetic acid, which enables the efficient synthesis of a wide range of anti 1,2-diols in moderate to good yields without the need for hazardous solvents or expensive transition metals as catalysts. [ABSTRACT FROM AUTHOR]

Formaldehyde (HCHO), which is one of the common pollutants in indoor environment and industrial processes, can cause adverse effects on human health. The thermal catalytic oxidation technology is regarded as the most promising approach due to its easy handling and environmental friendliness. This article reviews the current status of the catalytic oxidation of HCHO over noble metal and transition metal oxide catalysts. The general feature and the reaction mechanism of the catalytic oxidation of HCHO are summarized first. Based on the discussion of the reaction mechanism, the influence of some factors (catalyst preparation process, catalyst support, promoter and morphology) on the activity of the catalyst have been addressed. The structure of the catalysts has been elucidated and correlated with the reaction mechanism as well as the catalytic performance. Finally, the perspectives for the catalytic oxidation of HCHO in future research are presented. Hopefully, this review can shed light on the design of more active catalysts for HCHO oxidation to realize their practical application. [ABSTRACT FROM AUTHOR]

The development of highly efficient and cost-effective catalysts to drive the oxygen evolution reaction (OER) is of significant importance for sustainable energy and energy conversion. However, the acceleration of the sluggish kinetics of the OER relies primarily on the use of noble metals at present. In this work, we proposed a series of single/dual metal atoms loaded on N, S-doped graphene and investigated the OER mechanism with dual metal and nonmetal active sites at the atomic level using density functional theory (DFT). The theoretical results reveal that dual active sites, including the doping of N, S and dual transition metals in catalysts (M1M2N8S-gra, M1= Co, Ni, Fe, M2= Co, Ni, Fe, Cu), can reduce the overpotential and thereby synergistically promote the catalytic efficiency in the OER process. Notably, CoCo and FeFe based dual atoms catalysts exhibit the lowest theoretical overpotential and the promising OER catalytic activity. The superior catalytic activity arises from the modulated charge transfer between the catalysts and the adsorbed intermediates, appropriate adsorption energies for adsorption and desorption and resulted reduced overpotential, and can be attributed to the dual active sites with the incorporation of S and the second metal atoms. Our study provides theoretical insights into the dual active site mechanisms for the OER at the atomic level, offering a new perspective for designing high performance OER catalysts. [ABSTRACT FROM AUTHOR]

This Minireview presents and discusses recent developments in photoactive/photoluminescent N‐heterocyclic carbene (NHC) transition metal complexes and their viability as catalysts in bond‐forming photocatalysis. Specifically, we summarise key structural motifs adopted by photoactive NHC transition metal complexes and highlight some of their photophysical properties. Representative examples of their applications as catalysts in bond‐forming photochemical reactions are also showcased presenting the state‐of‐the‐art and future opportunities for this exciting class of NHC transition metal complexes. [ABSTRACT FROM AUTHOR]

The dehydrogenative coupling of alcohols and amines to form amide bonds is typically catalysed by homogeneous transition metal catalysts at high temperatures ranging from 130–140 °C. In our pursuit of an efficient and recyclable photocatalyst capable of conducting this transformation at room temperature, we report herein a COF‐mediated dehydrogenative synthesis. The TTT‐DHTD COF was strategically designed to incorporate a high density of functional units, specifically dithiophenedione, to trap photogenerated electrons and effectively facilitate hydrogen atom abstraction reactions. The photoactive TTT‐DHTD COF, synthesized using solvothermal methods showed high crystallinity and moderate surface area, providing an ideal platform for heterogeneous amide synthesis. Light absorption by the COF across the entire visible range, narrow band gap, and valence band position make it well‐suited for the efficient generation of excitons necessary for targeted dehydrogenation. Utilizing red light irradiation and employing extremely low loading of the COF, we have successfully prepared a wide range of amides, including challenging secondary amides, in good to excellent yields. The substrates' functional group tolerance, very mild reaction conditions, and the catalyst's significant recyclability represent substantial advancements over prior methodologies. [ABSTRACT FROM AUTHOR]

The crystalline dependent discharge process shows strong structure-reforming ability on surface and promotes the formation of vacancies and thus reducing the adsorption energy of intermediate. [Display omitted] Alkaline water electrolysis is apreferred technology for large-scale green hydrogen production. For most active transition metal-based catalysts during anodic oxygen evolution reaction (OER), the atomic structure of the anodic catalysts' surface often undergoes reconstruction to optimize the reaction path and enhance their catalytic activity. The design and maintenance of highly active sites during this reconstruction process remain critical and challenging for most OER catalysts. In this study, we explored the effects of crystal structures in pre-catalysts on surface reconstruction at low applied potential. Through experimental observation and theoretical calculation, we found out that catalysts with specific crystal structures exhibit superior surface remodeling ability, which enables them to better adapt to the conditions of the oxygen evolution reaction and achieve efficient catalysis. The discharge process enables the formation of abundant phosphorus vacancies on the surface, which in turn affects the efficiency of the entire oxygen evolution reaction. The optimized crystal structure of the catalyst results in an increase as high as 58.5 mA/cm2 for Ni 5 P 4 , which is twice as high as that observed for Ni 2 P. These results provide essential theoretical foundations and technical guidance for designing more efficient catalysts for oxygen evolution reactions. [ABSTRACT FROM AUTHOR]

Here, a series of nitrogen‐doped carbon (NC) supported transition metal oxide catalysts were prepared by pyrolysis of chitosan‐metal salt mixtures for the efficient synthesis 2,5‐diformylfuran (DFF) from 5‐hydroxymethylfurfural (HMF) and fructose. Among them, supported molybdenum‐based species on nitrogen‐doped carbon (Mo/NC) exhibited excellent activity and selectivity for selective oxidation of HMF to DFF. The presence of nitrogen species reduces the electron cloud density around the Mo species, thereby improving the catalytic activity. Moreover, the interaction between active MoO2 species on the catalyst surface and NC ensured the stability of the catalyst, resulting in no significant loss of activity after four catalytic cycles. 99.5 % and 55.1 % yields of DFF with full conversion were obtained from HMF and fructose respectively over Mo/NC‐chitosan‐600 in DMSO under ambient air. In order to enhance DFF yield from fructose, sulfonate groups were introduced into Mo/NC‐chitosan‐600 catalyst, leading to the highest DFF yield of 70.2 %. In addition, this catalyst also allowed 10.0%, 22.9% and 33.3% DFF yields from glucose, sucrose and inulin, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Quinazolines and their derivatives occur in various natural products and pharmaceuticals, and thus, various methods of synthesizing quinazolines have been explored. They have traditionally been synthesized via two‐component reactions, but these strategies often suffer from the unavailability of the starting materials and limited substrate scopes. To overcome these problems, three‐component reactions using additional N sources were developed. Aldehydes were initially used in these reactions, but alcohols are greener and less toxic than aldehydes. However, the previously reported methods involving the use of alcohols require the utilization of transition metal catalysts, ultrahigh temperatures, and extended durations. Thus, an efficient, practical method of synthesizing quinazolines using alcohol is desirable. A facile one‐pot three‐component method of synthesizing quinazolines utilizing alcohols, 2‐aminobenzoketones, and ammonium acetate is reported for the first time, using active MnO2 and tert‐butyl hydrogen peroxide (TBHP) as synergistic oxidants. MnO2 and TBHP play dual roles: First, they oxidize the alcohol to the aldehyde and then facilitate the transformation of the intermediate into the product. During alcohol oxidation, the synergistic effect of MnO2 and TBHP is particularly evident. The aldehydes generated in situ via alcohol oxidation undergo immediate subsequent reactions, thereby minimizing their volatilization and side reactions, such as oxidation and polymerization. [ABSTRACT FROM AUTHOR]

Hydrophosphination and oxyphosphination are two important topical reactions in order to prepare organophosphorus derivatives from unsaturated derivatives such as alkenes and alkynes in a more sustainable fashion. Noticeably, metal catalysed versions have shown great interest and efficiency. By contrast, the use of earth abundant transition metal based catalysts for such transformations is less reported, even if there is a growing interest during the last decade. This review article reports and highlights recent developments using manganese, iron, cobalt, nickel and copper based catalysts for hydro‐ and oxyphosphination, notably exhibiting the selectivity, functional group tolerance, milder conditions and catalyst design. Even if significant progresses were made, the scopes are still rather limited (mainly focused on activated olefins such as styrenes) and chemo‐ and stereo‐selectivity issues still have to be solved, notably for asymmetric transformations. Of interest, the use of visible light including blue one as activator emerged, giving promising and stimulating results at ambient conditions. [ABSTRACT FROM AUTHOR]

Electrochemical synthesis of NH3 from N2 utilizing single-atom catalysts (SACs) is a promising strategy for industrial nitrogen fixation and chemical raw material production. In this work, single transition metals (TMs) anchored on pyrazine-based graphene (TM@py-GY) are systematically studied to screen potential electrocatalysts for the nitrogen reduction reaction (NRR) using first-principles calculations. Particularly, the descriptor φ related to electronegativity and valence electron number is selected to clarify the trend of NRR activity, realizing a fast-scan/estimation among various candidates. After a four-step screening process, WI@py-GY and MoII@py-GY SACs are screened with good structural stability, high selectivity, and high activity. Meanwhile, the thermodynamic stability of WI@py-GY and MoII@py-GY SACs is demonstrated to ensure their feasibility in real experimental conditions. Furthermore, electronic properties are also examined in detail to analyze activity origin. This work not only provides an effective and reliable method for screening electrochemical NRR catalysts with excellent performance but also provides guidance for the rational design of SACs. [ABSTRACT FROM AUTHOR]

Nucleophilic vinylic substitution (SNV) by carbon nucleophiles allows the formation of vinylic C−C bonds without transition metal catalysts. In this paper, we show that tethering two alkenes together through a urea linkage can lead to the formation of a diene by an intramolecular SNV reaction. The starting materials are fully substituted N,N'‐diallyl ureas; the reaction proceeds in the presence of base, and entails a cascade of deprotonations, reprotonations, and an SNV reaction of an allylic carbanion on a rare electrophile: a vinylic urea. As a result, two allylic substituents couple to form a diene, despite the fact that neither is activated towards electrophilic attack. The reaction is tolerant of significant steric bulk, and exhibits regioselectivity with unsymmetrical diallyl ureas: β‐substituted allyl groups invariably behave as nucleophiles, while electrophilic behavior may be enforced by the use of an E‐vinylic urea substituent that cannot be deprotonated under the reaction conditions. [ABSTRACT FROM AUTHOR]

Defect engineering, by adjusting the surface charge and active sites of CoP catalysts, significantly enhances the efficiency of the oxygen evolution reaction (OER). We have developed a new Co1−xPv catalyst that has both cobalt defects and phosphorus vacancies, demonstrating excellent OER performance. Under both basic and acidic media, the catalyst incurs a modest overvoltage, with 238 mV and 249 mV needed, respectively, to attain a current density of 10 mA cm−2. In the practical test of alkaline electrocatalytic water splitting (EWS), the Co1−xPv || Pt/C EWS shows a low cell voltage of 1.51 V and superior performance compared to the noble metal-based EWS (RuO2 || Pt/C, 1.66 V). This catalyst's exceptional catalytic efficiency and longevity are mainly attributed to its tunable electronic structure. The presence of cobalt defects facilitates the transformation of Co2+ to Co3+, while phosphorus vacancies enhance the interaction with oxygen species (*OH, *O, *OOH), working in concert to improve the OER efficiency. This strategy offers a new approach to designing transition metal phosphide catalysts with coexisting metal defects and phosphorus vacancies, which is crucial for improving energy conversion efficiency and catalyst performance. [ABSTRACT FROM AUTHOR]

A one‐pot method has been developed for synthesizing diverse substituted 5‐aminotetrazoles via the electrochemically induced desulfurizative addition–cyclization of thioureas with azidotrimethylsilane. This methodology enables the construction of C−N and N−N bonds under mild reaction conditions without transition metal catalysts or external oxidizing agents. The applicability of this approach is demonstrated by its broad substrate scope, compatibility with various functional groups, scalability to gram‐scale synthesis, and practicality evidenced by the synthesis of an antibacterial agent. [ABSTRACT FROM AUTHOR]

Nickel has risen as a viable and cost‐effective substitute to noble metal catalysts in electrochemical hydrogen production, yet developing air‐stable and highly efficient nanostructured nickel‐based catalysts remains a significant challenge. Here a facile method for creating nanoporous Ni/NiO heterostructure catalysts for electrocatalytic hydrogen production is reported. The protocol employs chemical dealloying to establish a 3D bicontinuous nanoporous structure, followed by a controlled oxidation process to in situ generate uniform NiO surface layers atop the metallic nickel matrix in a self‐limiting manner. This approach not only yields highly active nickel‐based catalysts through a simple and controlled procedure but also effectively mitigates the auto‐ignition issue inherent in nanosized Ni, thereby enhancing air stability. By leveraging the synergistic interaction between Ni‐NiO co‐catalysis and improved access to intensified active sites, the electrocatalysts exhibit superior performance in the hydrogen evolution reaction, markedly outperforming noble Pt/C catalysts, and high stability in alkaline environments. The exploration of self‐limiting oxidation in nanostructured transition metals opens new avenues for developing advanced metal/oxide heterostructure catalysts for diverse energy applications. [ABSTRACT FROM AUTHOR]

Homogenous advanced oxidation processes (AOPs) based on transition metal catalysts toward the activation of H2O2 to hydroxyl radical (•OH) have been widely applied to organic pollutants removal, such as Fenton and Fenton-like processes. These transition metal catalysts mostly flocculate as the pH increases. It's worth noting that the formed transition metal flocs are complex heterogeneous aggregations with active substances, providing diverse reaction spaces and interfaces. However, it is a challenge to distinguish the roles of transition metal flocs in the organic pollutants removal from homogeneous catalytic reactions. Herein, we unveiled a pathway for the long-lasting removal of organic pollutants via Cr flocs adsorbed with •OH (HO•-Cr flocs) using a stepwise method. First, adsorbed •OH (•OHads) within the HO•-Cr flocs was proved to be the active site forming hydrogen bond (H-bond) and van der Waals force with organic pollutants. Then, the presence of switchable electron transfer between Cr and OH groups within the HO•-Cr flocs was revealed, contributing to the persistent existence of •OHads and consequently ensuring the long-lasting organics removal. Further, this removal pathway of organic pollutants was confirmed during the leather wastewater treatment. These findings will complement a different pathway for organic pollutants removal via transition metal flocs and extend the lifetime of homogeneous AOPs based on transition metal catalysts, providing significant implications for their design and optimization. [ABSTRACT FROM AUTHOR]

The storage and transportation of hydrogen gas, a non-polluting alternative to carbon-based fuels, have always been challenging due to its extreme flammability. In this regard, formic acid (FA) is a promising liquid organic hydrogen carrier (LOHC), and over the past decades, significant progress has been made in dehydrogenating FA through transition metal catalysis. In this review, our goal is to provide a detailed insight into the existing processes to expose various mechanistic challenges associated with FA dehydrogenation (FAD). Specifically, methodologies catalyzed by pincer-ligated metal complexes were chosen. Pincer ligands are preferred as they provide structural rigidity to the complexes, making the isolation and analysis of reaction intermediates less challenging and consequently providing a better mechanistic understanding. In this perspective, the catalytic activity of the reported pincer complexes in FAD was overviewed, and more importantly, the catalytic cycles were examined in detail. Further attention was given to the structural modifications, role of additives, reaction medium, and their crucial effects on the outcome. [ABSTRACT FROM AUTHOR]

Bimetallic nickel-molybdenum nitride (NiMoN) catalysts have attracted great attention due to their remarkable similarity to group VIII noble metals in terms of electronic structure, good electron conductivity, and durability for the hydrogen evolution reaction (HER). However, the existing approaches for fabricating NiMoN catalysts usually entail a series of multiple steps and hazardous ammoniated ingredient. As a result, these methods are difficult to be scaled up for large-area fabrication towards industrial water splitting. Herein, a hierarchical composite NiMoN@Ni(OH) 2 @NF composite electrode with a sheet morphology was synthesized based on a rational combination of seawater etching and magnetron sputtering. This method is easily scalable for producing large-area electrodes with minimal pollution. The incorporation of Ni(OH) 2 @NF nanoarray carriers enhances the exposure of additional active sites on the NiMoN layer, thereby augmenting the electrochemically active specific surface area of the electrode.The as-synthesized NiMoN@Ni(OH) 2 @NF electrode demonstrates excellent HER activity, with an overpotential of 57 mV at 10 mA cm−2, and exhibits remarkable long-term catalytic stability for over 100 h at a current density of 100 mA cm−2.This study presents an eco-friendly and straightforward method for preparing large-scale transition metal nitride catalysts with high catalytic activity. Large-area NiMoN@Ni(OH) 2 @NF composite electrodes were prepared using a combination of environmentally friendly and cost-effective seawater etching, along with reactive magnetron sputtering methods. [Display omitted] • The NiMoN@Ni(OH) 2 @NF composite electrodes were fabricated utilizing a simple and eco-friendly method. • NiMoN@Ni(OH) 2 @NF demonstrates excellent electrocatalytic activity and stability for HER. • The technology demonstrates excellent potential for large-scale fabrication. [ABSTRACT FROM AUTHOR]

The search for alternative non‐noble transition metal catalysts able to evolve hydrogen has been the focus of intense research. Molecular complexes bearing redox‐active ligands have been reported as efficient electrocatalysts for hydrogen evolution reaction (HER). This study showcases a new family of nickel‐thiosemicarbazone complexes displaying significant activity for HER in DMF solvent using trifluoracetic acid as proton source. Following previous works in our group, the ligand was stereochemically tailored, placing methoxy groups at different locations and considering various combinations of positions. Three complexes within the series were shown to outperform the parent catalyst bearing the methoxy group in para position. Overall, the nickel catalyst having the chemical substituent in meta position displays the best catalytic performances while having the lowest overpotential. These results support that ligand stereochemical tailoring in metal complexes improves electrocatalytic HER and suggest that ligand tuning is a promising direction to enhance catalyst performances. [ABSTRACT FROM AUTHOR]

The electrooxidation of urea holds great potential for converting urea from wastewater into hydrogen, contributing to environmental protection and sustainable energy production. This necessitates the development of highly efficient and stable catalysts for the urea oxidation reaction (UOR). In this study, a NiCoCr‐LDH/NF (nickel‐cobalt‐chromium layered double hydroxide/nickel foam) electrode is successfully synthesized via a simple hydrothermal method, demonstrating excellent electrocatalytic performance with a low work potential of 1.38 V at a high current density of 100 mA cm−2. In situ, Raman spectra analysis revealed that the incorporation of chromium (Cr) facilitated the generation of active γ‐NiOOH species and catalyst reconstruction. Density functional theory (DFT) simulations confirmed that the lower formation energy of γ‐NiOOH is due to the weakened interaction of O─H bonds because of a narrow energy range of hybridization between O‐2pz orbitals and H‐1s orbitals. The introduction of Cr also improved the adsorption energy of urea molecules and its intermediates, thereby enhancing the overall activity of UOR. With its excellent electrocatalytic performance, unique electronic states, and coordination structures, the NiCoCr‐LDH/NF electrode showcases great potential for practical applications in the field of energy catalysis. [ABSTRACT FROM AUTHOR]

Through density functional theory calculations, the mechanism of CO oxidation to CO2 on single‐atom catalysts consisting of an atom of Ti, Fe, or Zn deposited on the surface of the Mo2CO2 MXene is investigated. In the case of Fe@Mo2CO2, a mechanism resembling that of Termolecular Langmuir–Hinshelwood (TLH) is thermodynamically and kinetically favored, displaying very exothermic CO2 formation, low activation energies, and easy CO2 desorption. On Ti@Mo2CO2, the dissociation of CO2 is almost barrierless and much more likely to occur than CO2 desorption, barring the usage of this surface as a catalyst for CO oxidation. Finally, on Zn@Mo2CO2, a hybrid Langmuir–Hinshelwood/Eley–Rideal (LH/ER) mechanism is thermodynamically and kinetically feasible. Here, after the first CO2 forms, with an energy barrier of only 0.62 eV, the second CO2 is formed spontaneously, and the Zn–CO2 interactions are weak enough to allow desorption. The calculated thermodynamic quantities and reaction rates at T = 300 K indicate that Fe@Mo2CO2 should be quite active toward CO oxidation, followed by Zn@Mo2CO2, while the Ti‐based model is inactive. The results add to the evidence that establishes single transition metal atoms adsorbed on MXene surfaces as cheap and easily obtainable catalysts that offer the best of both bare and functionalized MXenes. [ABSTRACT FROM AUTHOR]

A series of M(x)CoCeMgAlO mixed oxides with different transition metals (M = Cu, Fe, Mn, and Ni) with an M content x = 3 at. %, and another series of Fe(x)CoCeMgAlO mixed oxides with Fe contents x ranging from 1 to 9 at. % with respect to cations, while keeping constant in both cases 40 at. % Co, 10 at. % Ce and Mg/Al atomic ratio of 3 were prepared via thermal decomposition at 750 °C in air of their corresponding layered double hydroxide (LDH) precursors obtained by coprecipitation. They were tested in a fixed bed reactor for complete methane oxidation with a gas feed of 1 vol.% methane in air to evaluate their catalytic performance. The physico-structural properties of the mixed oxide samples were investigated with several techniques, such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), elemental mappings, inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction under hydrogen (H2-TPR) and nitrogen adsorption–desorption at −196 °C. XRD analysis revealed in all the samples the presence of Co3O4 crystallites together with periclase-like and CeO2 phases, with no separate M-based oxide phase. All the cations were distributed homogeneously, as suggested by EDX measurements and elemental mappings of the samples. The metal contents, determined by EDX and ICP-OES, were in accordance with the theoretical values set for the catalysts' preparation. The redox properties studied by H2-TPR, along with the surface composition determined by XPS, provided information to elucidate the catalytic combustion properties of the studied mixed oxide materials. The methane combustion tests showed that all the M-promoted CoCeMgAlO mixed oxides were more active than the M-free counterpart, the highest promoting effect being observed for Fe as the doping transition metal. The Fe(x)CoCeMgAlO mixed oxide sample, with x = 3 at. % Fe displayed the highest catalytic activity for methane combustion with a temperature corresponding to 50% methane conversion, T50, of 489 °C, which is ca. 40 °C lower than that of the unpromoted catalyst. This was attributed to its superior redox properties and lowest activation energy among the studied catalysts, likely due to a Fe–Co–Ce synergistic interaction. In addition, long-term tests of Fe(3)CoCeMgAlO mixed oxide were performed, showing good stability over 60 h on-stream. On the other hand, the addition of water vapors in the feed led to textural and structural changes in the Fe(3)CoCeMgAlO system, affecting its catalytic performance in methane complete oxidation. At the same time, the catalyst showed relatively good recovery of its catalytic activity as soon as the water vapors were removed from the feed. [ABSTRACT FROM AUTHOR]

The present review covers various advances in the field of metal‐catalyzed coupling of N‐tosylhydrazones with compounds containing C−H/heteroatom‐H bonds, including transition metal catalysts i. e. Pd, Rh, Cu, Ag, Ni and Co and resulting alkylated, alkenylated, alkynylated, allenylated, annulated and many other products. A metal carbene migratory insertion process play a key role in carbon‐carbon single bond (C−C) and carbon‐carbon double bond (C=C) formation and undergoes variety of cascade reactions to synthesize a wide scope of pharmaceutically and medicinally valuable scaffoldings. [ABSTRACT FROM AUTHOR]

The use of alkaline earth‐abundant metal catalysts as alternatives to transition metal catalysts in the depolymerization of plastic waste is a very important research area. In this work, the first method is described for the conversion of polyesters into value‐added compounds catalyzed by a magnesium catalyst. It is demonstrated that the commercially available, inexpensive and air‐stable, alkaline earth magnesium catalyst Mg(OTf)2 efficiently promotes the reductive depolymerization of several polyesters using pinacolborane (HBpin) as the reducing agent with good to excellent yields. This catalyst also remains very active in at least 12 consecutive polycaprolactone (PCL) reductive depolymerization reactions with yields between 89% and 81%. This magnesium catalyst is also efficient in the reductive depolymerization of the polycarbonate poly(bisphenol A carbonate) (PC.BPA). Furthermore, it is found that Mg(OTf)2 also successfully catalyzes the methanolysis of polyesters and polycarbonates at moderate temperature with excellent yields. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiO 1- x Te x nanodots were constructed by a complexation-photodeposition method. • The H 2 -production rate of TiO 2 can be obviously enhanced by NiO 1- x Te x cocatalyst. • The electron-deficient Ni δ+ and Te δ+ active sites can synchronously enhance the adsorption of H 2 O and H. • An optimized alkaline H 2 -production mechanism of NiO 1- x Te x cocatalyst was proposed. Suitable H 2 O and H adsorption on the surface of transition metal chalcogenide cocatalyst is highly required to achieve their excellent alkaline H 2 -evolution rate. However, the weak adsorption of H 2 O and H atoms on NiTe surface greatly hinders its alkaline H 2 -evolution efficiency. Herein, an electron-deficient modulation strategy is proposed to synchronously improve the adsorption of H 2 O and H atoms on NiTe surface, which can greatly improve the alkaline photocatalytic H 2 evolution of TiO 2. In this case, highly electronegative oxygen atoms are introduced into the NiTe cocatalysts to induce the formation of electron-deficient Ni δ+ and Te δ+ sites in the ultra-small-sized NiO 1- x Te x nanodots (0.5–2 nm), which can be uniformly loaded onto the TiO 2 surface to prepare the NiO 1- x Te x /TiO 2 photocatalysts by a facile complexation-photodeposition strategy. The resulting NiO 1- x Te x /TiO 2 (0.6:0.4) photocatalyst exhibits the optimal activity (2143.36 μmol g-1 h−1), surpassing the activity levels of TiO 2 and NiTe/TiO 2 samples by 42.3 and 1.8 times, respectively. The experimental and theoretical investigations have revealed that the presence of highly electronegative O atoms in the NiO 1- x Te x cocatalyst can redistribute the charges of Ni and Te atoms for the formation of electron-deficient Ni δ+ and Te δ+ active sites, thereby synchronously enhancing the adsorption of H 2 O on Ni δ+ sites and H on Te δ+ sites and promoting alkaline photocatalytic H 2 evolution. The current research about the synchronous optimization of the H 2 O and H adsorption offers a significant approach to design high-performance H 2 -evolution materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical nitrate reduction to ammonia is a promising alternative strategy for producing valuable ammonia. This prospective route, however, is subject to a slow electrocatalytic rate, which resulted from the weak adsorption and activation of intermediate species, and the low density electron cloud of active centers. To address this issue, we developed a novel approach by doping boron into metal hydroxyl oxides to adjust the electronic structure of active centers, and consequently, led a significant improvement in the Faraday efficiency upto approaching 100 %, as well as an impressive ammonia yield upto approximately 23 mg/h mgcat−1 at −0.6 V vs. reversible hydrogen electrode (RHE). Experimental data in mechanism demonstrate that the doped boron play a crucial role in modulating the local electronic environment surrounding the active sites Co. In situ Raman and FTIR spectra provide evidences that boron facilitates the formation of deoxidation and hydrogenation intermediates. Additionally, density functional theory (DFT) calculations support the notion that boron doping enhances the adsorption capability of intermediates, reduces the reaction barrier, and facilitates the desorption of NH 3. [ABSTRACT FROM AUTHOR]

Waste, often overlooked, stands out as a prime source of valuable products, meeting the demand for natural resources. In the face of environmental challenges, this study explores the crucial role of waste‐derived catalysts in sustainable practices, emphasizing the transformative potential of solid waste materials. Carbon‐based catalysts sourced from agricultural, municipal, and industrial waste streams can be transformed into activated carbon, biochar, and hydrochar which are extensively used adsorbents. Furthermore, the paper also highlights the potential of transition metal‐based catalysts derived from spent batteries, electronic waste, and industrial byproducts, showcasing their efficacy in environmental remediation processes. Calcium‐based catalysts originating from food waste, including seashells, eggshells, bones, as well as industrial and construction waste also find an extensive application in biodiesel production, providing a comprehensive overview of their promising role in sustainable and eco‐friendly practices. From mitigating pollutants to recovering valuable resources, waste‐derived catalysts exhibit a versatile role in addressing waste management challenges and promoting resource sustainability. By transforming waste into valuable catalysts, this study champions a paradigm shift towards a more sustainable and resource‐efficient future. [ABSTRACT FROM AUTHOR]

CoMnOx catalysts were prepared using a microwave (MW)/ultrasonic (US)-assisted method. Amorphous/crystalline regions in CoMnOx (MW = 250 W US = 300 W) increased the oxygen vacancy content and CoMnOx exhibited excellent activity for methane oxidation (T90 = 330 °C). A new approach is provided here to improve the activity of transition metal catalysts. [ABSTRACT FROM AUTHOR]

Cobalt catalysts have recently gained considerable attention as alternatives to catalysts based on precious transition metals such as Rh and Ir. Recently, Co/photoredox cooperative catalysis has emerged as a powerful tool that enables versatile transformations, including cycloaddition reactions of unsaturated compounds. In particular, 1,6‐diyne derivatives are fascinating substrates for these reactions because the corresponding exocyclic 1,3‐diene products can be further transformed into sp3‐rich carbocycles and heterocycles via functionalization of the diene moiety. The dual catalytic system can facilitate not only the cycloaddition based on the activation of the π‐bond only, such as alkyne cyclotrimerization, but also the cycloaddition involving σ‐bond activation. This Concept highlights the recent advances in Co/photoredox cooperative‐catalysis‐enabled cycloaddition reactions, focusing on the reactions of 1,6‐diyne substrates, which are difficult to perform when well‐defined cationic CoI catalysis is employed. [ABSTRACT FROM AUTHOR]

The transition metal‐catalyzed multi‐component cross‐electrophile sulfonylation, which incorporates SO2 as a linker within organic frameworks, has proven to be a powerful, efficient, and cost‐effective means of synthesizing challenging alkyl–alkyl sulfones. Transition metal catalysts play a crucial role in this method by transferring electrons from reductants to electrophilic organohalides, thereby causing undesirable side reactions such as homocoupling, protodehalogenation, β‐hydride elimination, etc. It is worth noting that tertiary alkyl halides have rarely been demonstrated to be compatible with current methods owing to various undesired side reactions. In this work, a zinc‐promoted cross‐electrophile sulfonylation is developed through a radical‐polar crossover pathway. This approach enables the synthesis of various alkyl–alkyl sulfones, including 1°‐1°, 2°‐1°, 3°‐1°, 2°‐2°, and 3°‐2° types, from inexpensive and readily available alkyl halides. Various functional groups are well tolerated in the work, resulting in yields of up to 93%. Additionally, this protocol has been successfully applied to intramolecular sulfonylation and homo‐sulfonylation reactions. The insights gained from this work shall be useful for the further development of cross‐electrophile sulfonylation to access alkyl–alkyl sulfones. [ABSTRACT FROM AUTHOR]

Herein we report the first transition metal‐catalyzed approach to the enantioenriched synthesis of cyclic sulfonimidamides relying on commercially available palladium catalysts and ligands. High‐throughput experimentation (HTE) was employed to identify the optimal catalyst system and solvent. The method is applied to a variety of saturated and unsaturated rings and exhibits the highest selectivity for 2‐substituted allyl electrophiles. The products are further elaborated to complex, tricyclic scaffolds. DFT experiments presented herein highlight the key ligand substrate interactions leading to the high levels of enantioselectivity. [ABSTRACT FROM AUTHOR]

Inspired by the favorable impact of heteroatom‐containing groups in phenoxy‐imine titanium and late transition metal catalysts, a series of novel pyridylamido hafnium catalysts bearing ─OMe (Cat‐OMe), ─CF3 (Cat‐CF3), and ─C6F5 (Cat‐C6F5) substituents are designed and synthesized. Together with the established hafnium catalysts Cat‐H and Cat‐iPr by Dow/Symyx, these catalysts are applied in the polymerization of α‐olefins, including 1‐hexene, 1‐octene, and 4M1P, as well as in the copolymerization of these α‐olefins with a specifically designed polar monomer. The enhancement of polymer molecular weight derived from catalyst modification and the incorporation of polar monomers is discussed in detail. Notably, the new catalysts are all highly active for α‐olefins polymerization, with catalyst Cat‐CF3 producing isotactic polymers with the highest molecular weight (Mw = 1649 kg mol−1); in copolymerization with polar monomers, catalyst Cat‐OMe yields isotactic copolymer with the highest molecular weight (Mw = 2990 kg mol−1). Interestingly, catalyst Cat‐C6F5 bearing a ─C6F5 group in the N‐aryl moiety gives rise to poly(α‐olefin) with reduced stereoselectivity. The findings of this study underscore the potential of heteroatom‐containing groups in the development of early transition metal catalysts and the synthesis of polymer with novel structures. [ABSTRACT FROM AUTHOR]