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Biomimetic metalloporphyrin complexes have been employed in a number of catalytic oxidation reactions by utilizing terminal oxidants such as iodosylarenes (ArIO). Although high‐valent metal‐oxo species have been considered as the reactive intermediates, their precursors, metal‐iodosylarene adduct species, also exhibit intriguing oxidation capability under certain conditions. However, late transition metal porphyrin‐oxidant adduct species have not been explored in oxidation reactions yet. Herein, we report the synthesis, characterization and reactivity studies of cobalt(III) porphyrin‐ArIO adduct complexes. These adduct species exhibit moderate oxidation capability in electron transfer reactions. More interestingly, addition of Brønsted acid or Lewis acid facilitated the O−I bond cleavage, resulted in the formation of cobalt(III) porphyrin π‐cation radical species, which is much more reactive than the corresponding adduct species in electron transfer reactions. Kinetic studies and theoretical calculations demonstrate that the O−I bond cleavage is triggered in the presence of acid, affording the porphyrin ligand oxidation while the formation of high‐valent cobalt‐oxo species is prohibited due to the "oxo‐wall" for late transition metals. This study provides a novel model of a late transition metal‐iodosylarene adduct species as an active oxidant in oxidation reactions, while in the cases of iron and manganese complexes, high‐valent metal‐oxo species are generated. [ABSTRACT FROM AUTHOR]

ZnZrOx solid solution is a promising catalyst for the hydrogenation of CO2 to methanol, but precise design of the nanostructure to enhance catalytic performance remains a significant challenge. Herein, a ZnZrOx-based solid solution (ZnZrOx-MD) nanoparticle catalyst with uniform metal dispersion and remarkable CO2 activation ability was developed via calcination of metal–organic frameworks [MOFs, viz., PCN-223-(Zn)] with mixed metal (Zr and Zn) as solid precursors. It was found that the ZnZrOx-MD nanoparticle catalyst outperformed its counterparts prepared using a traditional deposition–precipitation method (ZnZrOx-TD). Furthermore, the effects of the micromorphology and crystal composition on the catalytic performance of ZnZrOx-MD were systematically investigated. Comprehensive characterization results reveal that ZnZrOx-MD contained abundant oxygen vacancies, large specific surface area, and uniform metal dispersion, which collectively contributed to its excellent CO2 hydrogenation performance, resulting in a high methanol selectivity of 77.2% at 320 °C. In situ DRIFTS experiments confirm the mechanism for the CO2 hydrogenation to methanol over the ZnZrOx nanoparticle catalysts involved the initial formation of HCOO* species, followed by subsequent hydrogenation to generate CH3O* and ultimately produce methanol. Overall, this work highlights the potential benefits of MOFs as thermal decomposition precursors for the fabrication of solid-state catalysts with unique properties. [ABSTRACT FROM AUTHOR]

Encapsulation of transition metals represents a crucial method for modifying the electronic structure and regulating the reactivity of fullerene, thereby expanding its applications. Herein, we present calculations with density functional theory methods to investigate the mechanisms of the Diels‐Alder (DA) reactions of cyclopentadiene and La@C60 or Gd@C60 as well as their tricationic derivatives. Our findings indicate that the encapsulation of La and Gd into the C60 cage is thermodynamically favorable. The DA reactions are favored by the presence of La and Gd, with lower barriers, though the regioselectivity, favoring 6−6 bonds in the fullerene, is not affected. The effect of external electric fields has been also considered. [ABSTRACT FROM AUTHOR]

Boron subphthalocyanines with chloride and fluoride axial ligands and three antimony complexes chelated by corroles that differ in size and electron‐richness were examined as electrocatalysts for reduction of protons to hydrogen. Experiment‐ and computation‐based investigations revealed that all redox events are ligand‐centered and that the meso‐C of the corroles and the peripheral N atoms of the subphthalocyanines are the largely preferred proton‐binding sites. [ABSTRACT FROM AUTHOR]

The chemical space of chiral Brønsted acid catalysts is defined by quantity and complexity, reflecting the diverse synthetic challenges confronted and the innovative molecular designs introduced. Here, we detail how this successful outcome is a powerful demonstration of the benefits of utilizing both local structure searches and a comprehensive understanding of catalyst performance for effective and efficient exploration of Brønsted acid properties. In this concept article we provide an evolutionary overview of this field by summarizing the approaches to catalyst optimization, the resulting structures, and functions. [ABSTRACT FROM AUTHOR]

In this research work, we examined the decomposition mechanisms of N-substituted diacetamides. We focused on the substituent effect on the nitrogen lone-pair electron delocalization, with electron-withdrawing and electron donor groups. DFT functionals used the following: B1LYP, B3PW91, CAMB3LYP, LC-BLYP, and X3LYP. Dispersion corrections (d3bj) with Becke–Johnson damping were applied when necessary to improve non-covalent interactions in the transition state. Pople basis sets with higher angular moments and def2-TZVP basis sets were also applied and were crucial for obtaining consistent thermodynamic parameters. The proposed mechanism involves a six-membered transition state with the extraction of an α hydrogen. Several conformers of N-diacetamides were used to account for the decrease in entropy in the transition state in the rate-determining state. All calculations, including natural bond orbital (NBO) analyses, were performed using the Gaussian16 computational package and its GaussView 6.0 visualizer, along with VMD and GNUPLOT software. The isosurfaces and IBSIs were calculated using MultiWFN and IGMPlot, respectively. [ABSTRACT FROM AUTHOR]

Acridinium esters, due to their capability for chemiluminescence (CL), are employed as indicators and labels in biomedical diagnostics and other fields. In this work, the influence of ionic surfactants, hexadecyltrimethylammonium chloride and bromide (CTAC and CTAB, cationic) and sodium dodecyl sulphate (SDS, anionic) on the CL parameters and mechanism of representative emitter, 10-methyl-9-[(2-methylphenoxy)carbonyl]acridinium trifluoromethanesulphonate (2MeX) in a H2O2/NaOH environment, is studied. Our investigations revealed that the type of surfactant and its form in solution have an impact on the CL kinetic constants and integral efficiencies, while changes in those emission properties resulting from the type of ion (Cl− vs. Br−) are negligible. The major changes were recorded for systems containing surfactants at concentrations higher than the critical micelle concentration. The cationic surfactants (CTAC, CTAB) cause a substantial increase in CL emission kinetics and a moderate increase in its integral efficiency. At the same time, the opposite effect is observed in the case of SDS. Molecular dynamics simulations suggest that changes in emission parameters are likely due to differences in the binding strength of 2MeX substrate with surfactant molecules, which is higher for SDS than for CTAC. The results can help in rational designing of optimal acridinium CL systems and demonstrate their usefulness in distinguishing the pre- and post-micellar environment and the charge of surfactants. [ABSTRACT FROM AUTHOR]

The lack of basic research is a principal reason restricting the widespread application of aluminum phosphate adhesive, such as its reaction mechanism is not yet clear. Herein, we investigate the dissolution behavior of aluminum oxide (Al 2 O 3) in acid aluminum phosphate (AAP) solution and the effects of Al 2 O 3 addition, calcination temperature and phosphorus to aluminum (P/Al) ratio of the AAP solution on the thermal evolution, phase development and hygroscopic behavior of aluminum phosphate adhesive. The dissolution process of Al 2 O 3 in AAP solution is controlled by external diffusion. The thermal evolution of aluminum phosphate adhesives is a complex process that is a function of Al 2 O 3 addition and calcination temperature. Although it is a linear process, many of the reactions are largely coupled and occur simultaneously. The hygroscopic mechanism of aluminum phosphate adhesives is associated to the hydrophilicity of the hydroxyl groups (P–OH). Increasing the calcination temperature and the Al 2 O 3 addition can improve the hygroscopicity resistance properties. Finally, the mechanical and dielectric properties of the quartz fiber cloth reinforced aluminum phosphate matrix composites (SiO 2f /aluminum phosphate composites) were also investigated. The results demonstrate that the composites have the characteristics of light weight, high strength, and excellent dielectric properties, suggesting that they have attractive applications in radome materials. [ABSTRACT FROM AUTHOR]

Ammonia is considered a clean energy carrier because of its high hydrogen content, ease of liquefaction, and low carbon emissions. It is mostly manufactured by the Haber–Bosch process. It is critical to the advancement of society and the welfare of people. However, because of the high temperatures and high pressures involved in this process—which uses iron catalysts and fossil fuels to produce hydrogen—it produces greenhouse gasses and requires a lot of energy. Although they struggle with high catalyst prices and low production rates, researchers have looked into alternative ammonia synthesis methods like electrochemical and photochemical ways to overcome this. In order to enable synthesis at lower temperatures and pressures, current efforts are concentrated on creating novel catalysts that will lower reaction conditions. Recent developments in heterogeneous catalysts, including oxides, metal hydrides, oxyhydrides, and electrides, for thermal ammonia synthesis are highlighted in this review. Due to their distinct surface characteristics or electronic structures, these materials have the ability to reduce catalyst poisoning and increase activity while facilitating the breaking of N N bonds and the storage and release of hydrogen. In order to support the development of effective catalysts for a more sustainable future, we investigate variables influencing catalyst performance and reaction processes. Our goal is to provide guidance for future catalyst design and thermal ammonia synthesis methods. [Display omitted] • A review of recent advances in thermocatalytic ammonia synthesis is discussed. • A detailed classification of heterogeneous catalyst types is presented. • The reaction mechanism of ammonia synthesis over catalysts is analyzed. • The relationship between catalyst activity and structure is explained. • Design ideas for functional support materials are provided. [ABSTRACT FROM AUTHOR]

The effects of H2O in heterogeneous catalysis of COx (CO2, CO) hydrogenation have been intricate and controversial for many years. On the one hand, H2O molecules and their derivatives (O, H, OH) serve as reactants or co‐reactants, playing a role in modulating the reaction pathway through specific mechanisms. On the other hand, the presence of H2O can influence the catalytic performance by altering the physicochemical properties of the catalyst, such as particle size and chemical state, among others. More importantly, the dual role of H2O leads to both positive and negative outcomes, challenging our understanding of its impact. In this mini review, the relevant research results are summarized in terms of the promoting and inhibiting effects of H2O of the COx hydrogenation reaction (e. g., synthesis of methanol, Fischer‐Tropsch synthesis, methanation, etc.) and discussed from the perspective of catalyst and reaction mechanism, which may provide a certain theoretical basis for the design and development of high‐performance catalysts and referable experience for the further exploration and utilization of H2O effects on related fields as well. [ABSTRACT FROM AUTHOR]

Copper‐catalyzed C─H oxygenation has drawn considerable attention in mechanistic studies. However, a comprehensive investigation combining radical pathways with a metal‐catalytic cycle is challenged by the intricate organic radicals and metallic intermediates. Herein, an online coupled EPR/UV–vis/near‐IR detecting method is developed to simultaneously monitor both reactive radical species and copper complex intermediates during the reaction. Focusing on copper‐catalyzed phenol oxygenation with cumene hydroperoxide, the short‐lived alkylperoxyl radical (EPR signal at g = 2.0143) as well as the unexpected square planar Cu(II)‐alkoxyl radical complex (near‐IR signal at 833 nm) are unveiled during the reaction, in addition to the observable phenoxyl radical in EPR, quinone product in UV–vis, and Cu(II) center in EPR. With a comprehensive picture of diverse intermediates evolving over the same timeline, a novel Cu(I)/Cu(II) proposed relay‐catalyzed sequential radical pathway. In this sequence, Cu(II) activates hydroperoxide through Cu(II)‐OOR into the alkylperoxide radical, while the reaction between Cu(I) and hydroperoxide leads to Cu(II)(•OR)OH with high H‐atom abstracting activity. These results provide a thorough understanding of the Cu(I)/Cu(II) relay catalysis for phenol oxygenation, setting the stage for mechanistic investigations into intricate radical reactions promoted by metallic complexes. [ABSTRACT FROM AUTHOR]

Fabrication of batch‐wise efficient, user‐ and environmentally‐friendly, and well‐defined yield methods for the synthesis of graphite oxide, the main precursor to graphene oxide and its reduced derivative, is an essential and robust research field, yet is sparingly investigated or innovated in recent years. This concept review showcases recent potential advances in the fabrication of electrochemical electrodes that meet aforementioned design parameters, wherein working electrode construction is seen to play a key role in shaping the yield characteristics and aiding the mechanistic understanding of efficiency of adopted methods. Particularly, those advances pave the way for new and various tunable design parameters by fabricating different methods of encapsulating graphite powder instead of using conventional bare monolith forms of graphite as working electrode. Encapsulation geometry, pressure, and matrix material, as well as powder size are examples of such tunable design parameters which are lacking in the monolith methods. The encapsulation validates authenticity of real‐time monitoring of electrochemical intercalation, exfoliation, and oxidation of graphite powder, thereby offering excellent and well‐defined control on yield. [ABSTRACT FROM AUTHOR]

Fluorination of heterocyclic compounds accompanied by molecular rearrangements is an area of synthesis experiencing rapid advances. One of the characteristics of electrophilic and oxidative fluorination is the involvement of carbocations, radicals, and radical ions which can undergo rearrangements. Such rearrangements expand the range of fluorinated products, which are sometimes difficult to access by direct fluorination of heterocyclic compounds. The purpose of this review is to systematize and analyze the literature data published over the past decade on fluorination of heterocyclic compounds accompanied by molecular rearrangements. Particular attention is paid to the analysis of reaction mechanisms and the problem of selectivity. [ABSTRACT FROM AUTHOR]

Hydrogenation of CO2 represents a promising pathway for converting it into valuable hydrocarbons and clean fuels like dimethyl ether (DME). Despite significant research, several challenges persist, including a limited understanding of reaction mechanisms, thermodynamics, the necessity for catalyst design to enhance DME selectivity, and issues related to catalyst deactivation. The paper provides a comprehensive overview of recent studies from 2012 to 2023, covering various aspects of CO2 hydrogenation to methanol and DME. This review primarily focuses on advancing the development of efficient, selective, and stable innovative catalysts for this purpose. Recent investigations that have extensively explored heterogeneous catalysts for CO2 hydrogenation were summarized. A notable focus is on Cu-based catalysts modified with promoters such as Zn, Zr, Fe, etc. Additionally, this context delves into thermodynamic considerations, the impact of reaction variables, reaction mechanisms, reactor configurations, and recent technological advancements, such as 3D-printed catalysts. Furthermore, the paper examines the influence of different parameters on catalyst deactivation. The review offers insights into direct CO2 hydrogenation to DME and proposes paths for future investigation, aiming to address current challenges and advance the field. [ABSTRACT FROM AUTHOR]

This study investigated degradation behaviors of a nonsteroidal anti-inflammatory drug Nabumetone (NMT) and its major metabolite 6-methoxy-2-naphthylacetic acid (MNA) in the coupling process of ultraviolet and monochloramine (UV/NH 2 Cl). The second-order rate constants of the contaminants reacting with reactive radicals (HO•, Cl•, Cl 2 •⁻, and CO 3 •⁻) were determined by laser flash photolysis experiments. HO• and Cl• contributed predominantly with 52.3% and 21.7% for NMT degradation and 60.8% and 22.3% for MNA degradation. The presence of chlorides retarded the degradation of NMT, while promoted the destruction of MNA, which was ascribed to the photosensitization effects of MNA under UV irradiation. Density functional theory (DFT) calculations revealed that radical adduct formation (RAF) was dominant pathway for both HO• and Cl• reacting with the contaminants, and hydrogen atom transfer (HAT) preferred to occur on side chains of NMT and MNA. NMT reacted with NO 2 • through single electron transfer (SET) with the second-order rate constant calculated to be 5.35 × 107 (mol/L)−1 sec−1, and the contribution of NO 2 • was predicted to be 13.0% of the total rate constant of NMT in pure water, which indicated that NO 2 • played a non-negligible role in the degradation of NMT. The acute toxicity and developmental toxicity of NMT were enhanced after UV/NH 2 Cl treatment, while those of MNA were alleviated. The transformation products of both NMT and MNA exhibited higher mutagenicity than their parent compounds. This study provides a deep understanding of the mechanism of radical degradation of NMT and MNA in the treatment of UV/NH 2 Cl. [ABSTRACT FROM AUTHOR]

C–H bond activation is a crucial synthetic strategy widely utilized in both academic and industrial settings. Due to the strong and kinetically inert nature of the C–H bond, its functionalization typically requires metal-based catalysts. This review highlights the most significant advancements in homogeneously catalyzed reactions using pincer complexes with metals from groups 8–10, capable of promoting challenging C–H activation, published since 2010. In particular, it focuses on C–H bond activation for borylation, isomerization, and dehydrogenation, among other processes, discussing their scope and mechanistic insights. [ABSTRACT FROM AUTHOR]

The study of the reaction mechanism of sea salt solution (SSS) on asphalt binder was important for the development of perpetual asphalt pavements in coastal areas. For this, a novel modifier (MPGJ-I) was developed in this study using phosphogypsum whiskers (PSW) synthesized from phosphogypsum (PSP) wastes, then the prepared composite-modified asphalt binders and base asphalt binders were immersed in the SSS with six concentrations. Then, the surface free energy (SFE) test, rheological tests, and Fourier transform infrared spectroscopy (FTIR) test were used to investigate the function mechanism of SSS on the surface properties, rheological properties, and chemical structure. The results showed that the salt in SSS would gradually transfer to the inside of asphalt binder, and with the increase in SSS concentration, the mass accumulation rate of base asphalt binders increased by 0.84% and 0.72%, whereas the modified asphalt binders only increased by 0.64% and 0.61%, respectively. The MPGJ-I effectively alleviated the decline trend of surface properties, with the incorporation of MPGJ-I, the SFE and cohesive work of base asphalt binders increased by 29.14%–32.83% and 5.23%–48.63%, respectively. In addition, with the increase in SSS concentration, the rutting factor (G*/sinδ), and creep recovery rate (R) of base asphalt binders increased by 15.44%–57.69% and 7.58%–22.34%, respectively, and the fatigue life (Nf) decreased by 6.08%–47.24%. Whereas G*/sinδ and R of modified asphalt binders increased by 10.07%–50.77% and 2.15%–19.35%, respectively, and Nf decreased by 1.79%–8.89%, which meant that the incorporation of MPGJ-I effectively restrained the attack action of SSS on base asphalt binders. There was a chemical reaction between SSS and asphalt binder, and the peak intensity of the new characteristic peaks in asphalt binder was positively correlated with SSS concentration, the incorporation of MPGJ-I could reduce the increasing rate of peak intensity to a certain degree. In addition, the principal component analysis (PCA) model showed that the surface properties and fatigue performance were closely related to the SSS concentration, and this correlation was not affected by the modification effect of MPGJ-I. [ABSTRACT FROM AUTHOR]

In this work, we propose a multi-level protocol for routine theoretical studies of chemical reaction mechanisms. The initial reaction paths of our investigated systems are sampled using the Nudged Elastic Band (NEB) method driven by a cheap electronic structure method. Forces recalculated at the more accurate electronic structure theory for a set of points on the path are fitted with a machine learning technique (in our case symmetric gradient domain machine learning or sGDML) to produce a semi-local reactive potential energy surface (PES), embracing reactants, products and transition state (TS) regions. This approach has been successfully applied to a unimolecular (Bergman cyclization of enediyne) and a bimolecular (SN2 substitution) reaction. In particular, we demonstrate that with only 50 to 150 energy-force evaluations with the accurate reference methods (here complete-active-space self-consistent field, CASSCF, and coupled-cluster singles and doubles, CCSD) it is possible to construct a semi-local PES giving qualitative agreement for stationary-point geometries, intrinsic reaction coordinates and barriers. Furthermore, we find a qualitative agreement in vibrational frequencies and reaction rate coefficients. The key aspect of the method's performance is its multi-level nature, which not only saves computational effort but also allows extracting meaningful information along the reaction path, characterized by zero gradients in all but one direction. Agnostic to the nature of the TS and computationally economic, the protocol can be readily automated and routinely used for mechanistic reaction studies. [ABSTRACT FROM AUTHOR]

Mechanism degradation of ethylene terephthalate momer was investigated by density functional theory B3P86/6-31++G (d, p) method, the possible reaction paths of pyrolysis/hydrolysis/alcoholysis and catalytic degradation were designed, the geometric structures of various intermediates, transition states, and products involved in the reaction were optimized, and their frequencies were calculated to gain the thermodynamic and kinetic parameters. The calculation results show that: When water or methanol is used as a catalyst in the ethylene terephthalate process of thermal degradation, the use water or methanol O-H provides H to the main chain of the ethylene terephthalate ester bond on the carbonyl O atom is form terephthalic acid, and ethyl C off H atoms and (water) hydroxyl (-OH) or (methanol) methoxy group (-OCH3) are combined to form new water or methanol, thereby reducing the reaction energy barriers during the pyrolysis of ethylene terephthalate (251.4 kJ/mol→181.1 kJ/mol (methanol) and 187.5 kJ/mol (water)). When water or methanol is reactant in the thermal degradation process of ethylene terephthalate, H in water or methanol O-H is supplied to the carbonyl O atom of the main chain of ethylene terephthalate to form ethylene glycol. Hydroxy group (-OH) in water or methoxy group (-OCH3) in methanol binds to the carbonyl C atom of the carbonyl group of ethylene terephthalate backbone to form terephthalic acid or mono-methyl terephthalate, it further reduces the reaction energy barriers (156.4 kJ/mol (methanol) and 170.1 kJ/mol (water)) during the pyrolysis of ethylene terephthalate. In the reaction process, either water/methanol as catalysis or water/methanol as reactants can reduce the reaction energy barrier of the main element step to a certain extent, so that the reaction is easy to proceed. [ABSTRACT FROM AUTHOR]

The primary objective of this work is to delve into the intricacies of allylic fluorination reactions through the application of density functional theory (DFT) calculations. These reactions hold significant importance in the realm of synthesizing organofluorine compounds. The specific focus lies on comprehending the interaction mechanisms when styrenes, a class of organic molecules, come in contact with an electrophilic fluorinating reagent known as Selectfluor. Notably, this interaction pathway demonstrates remarkable efficiency in yielding allylic fluoride products. The proposed mechanism for this transformation involves a sequential process. To unveil the microcosmic intricacies governing this reaction between the alkene substrate and Selectfluor, advanced computational methodologies are employed. The paper systematically outlines the computational strategies harnessed to probe the minute details of the reaction mechanism. The outcomes of these computations are subsequently subjected to thorough analysis, encompassing crucial facets such as transition states and energy barriers. This analytical depth enhances the fundamental understanding of the reaction mechanism and sheds light on the underlying factors influencing its feasibility and efficiency. In a broader context, the insights garnered from this study carry significant utility. They provide pivotal guidance for the optimization of reaction conditions, facilitating the fine-tuning of experimental setups. Moreover, the elucidated mechanism serves as a platform for the design of even more efficient and selective allylic fluorination reactions. This paper, by amalgamating theoretical insights with practical synthetic objectives, contributes to the broader advancement of organofluorine compound synthesis and allied fields. [ABSTRACT FROM AUTHOR]

The atroposelective transformation of alkynes is an efficient protocol for the assembly of axially chiral compounds. Benefitting from the rapid development of chiral organocatalysts, the organocatalytic atroposelective reactions of alkynes have been extensively studied over the past decades. An array of chiral catalysts, including chiral Brønsted acid catalysts, secondary amine catalysts, N -heterocyclic carbene (NHC) catalysts, thiourea catalysts and N -squaramide catalysts, are employed in enantioselective reactions of different alkynes. This short review summarizes the recent advances on organocatalytic atroposelective reactions of alkynes according to the type of alkyne substrate. The reaction mechanisms, modes of enantiocontrol, product diversity and applications are highlighted. 1 Introduction 2 Electron-Rich Aryl Alkynes 3 Electron-Deficient Aryl Alkynes 4 Other Types of Alkynes 5 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem. Among various nitrate removal technologies, electrocatalytic nitrate reduction reaction (eNO3RR) has been widely studied for its advantages of being eco-friendly, easy to operate, and controllable under environmental conditions with renewable energy as the driving force. Transition metal-based catalysts (TMCs) have been widely used in electrocatalysis due to their abundant reserves, low costs, easy-to-regulate electronic structure and considerable electrochemical activity. In addition, TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction, the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity. Based on this, this review firstly discusses the mechanism as well as analyzes the two main reduction products (N2 and NH3) of eNO3RR, and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism. Secondly, this review mainly focuses on the recent advances in the direction of eNO3RR with four types of TMCs, Fe, Co, Ni and Cu, and unveils the interfacial modulation strategies of Fe, Co, Ni and Cu catalysts for the activity, reaction pathway and stability. Finally, reasonable suggestions and opportunities are proposed for the challenges and future development of eNO3RR. This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts (NMCs) for eNO3RR. [ABSTRACT FROM AUTHOR]

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Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-value-added chemicals, but it is hampered by sluggish charge dynamics and limited redox potential. Herein, a porous S-doped carbon nitride (S-C3N4−y) foam assembled from ultrathin nanosheets with rich nitrogen vacancies was synthesized using a molecular self-assembly strategy. The S dopants and N vacancies synergistically adjusted the band structure, facilitating light absorption and enhancing the oxidation ability. Moreover, the ultrathin nanosheets and porous structure provided more exposed active sites and facilitated mass and charge transfer. Consequently, S-C3N4−y foam exhibited enhanced photocatalytic activities for synchronous hydrogen evolution (4960 µmol/(h·g)) and benzylamine oxidation to N-benzylidenebenzylamine (4885 µmol/(h·g)) with high selectivity of > 99 %, which were approximately 17.6 and 72.9 times higher than those of bulk CN, respectively. The photocatalytic coupling pairing reaction promotes the water splitting by consuming H2O2, thereby improving the hydrogen evolution efficiency and achieving the production of high value-added imines. This study provides an effective route for regulating the morphology and band structure of carbon nitride for synthesizing highly valuable chemicals. [ABSTRACT FROM AUTHOR]

Ammonia as a green energy source has attracted a lot of attention in recent years. Despite its industrial intensity, the Haber‐Bosch process remains a primary ammonia source, emitting significant CO2 (≈2.9 tons per ton of ammonia). Future ammonia synthesis methods aim to surpass the Haber‐Bosch process by operating under milder conditions. These methods encompass chemical looping, thermal catalysis, electrochemical catalysis, photocatalysis, and plasma catalysis, albeit with inherent limitations. Although thermal catalysis has reduced conditions to ≈5 MPa, innovative catalysts are still scarce. Electrochemical catalysis produces hydrogen via water electrolysis but encounters challenges in Faraday efficiency and ammonia yield. Photocatalytic synthesis, while energy‐efficient, suffers from sluggish reaction rates. Plasma synthesis, while achieving low temperatures and pressures, faces difficulties in ammonia yield amidst competitive reactions. Chemical looping synthesis, enabling independent nitrogen fixation and hydrogenation, lacks efficient nitrogen transport catalysts. Effective catalysts are a common requirement across these methods. This review explores recent advancements, elucidating reaction mechanisms, nitrogen activation, and catalyst performance, while discussing the strengths, weaknesses, and future prospects of ammonia synthesis technologies to foster further innovation in the field. [ABSTRACT FROM AUTHOR]

It is imperative to have an in-depth understanding of the mechanism of action for the role of moisture in a coal matrix during coal spontaneous combustion, not only for preventing fires in the coal industry but also for reducing emissions of hazardous gases. In this study, the method of isotope tracing was first introduced to study the mechanism of moisture in the spontaneous combustion of coal. Moisture in a coal matrix was labeled separately using D2O and H218O, and the coal samples with internal moisture and external moisture were prepared by controlling the drying temperature. Coal samples with different isotopic moisture were heated using a spontaneous combustion apparatus. The gaseous products (CO2, CO, and CH4) were measured using a GC-950 gas chromatography equipped with a flame photometric detector, and simultaneously, the isotopic gases (including C18O, C18O2, CH3D) were timely monitored using an online mass spectrometer. The appearance of isotopic gases directly proved that the moisture could participate in the spontaneous combustion of coal in atomic level, and the moisture in the coal matrix is involved in the spontaneous combustion of coal through chemical reaction. Based on the experimental results, the pathways of the oxygen atom and H atom from the moisture participating in the production of isotopic gases were investigated. The reaction mechanism of moisture participating in the spontaneous combustion of coal was also explored based on the migration law of oxygen and hydrogen atoms of H2O molecule in coal matrix. [ABSTRACT FROM AUTHOR]

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Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Apart from electrode material modification, architecture design and optimization are important approaches for improving lithium–sulfur battery performance. Herein, an integrated structure with tandem connection is constructed by confining nanosulfur (NS) in conductive poly(3,4‐ethylenedioxythiophene) (PEDOT) reaction chambers, forming an interface of discrete independent nanoreactor units bonded onto carbon nanotubes (noted as CNT/NS@PEDOT). The unique spatial confinement and concentration gradients of sulfur@PEDOT nanoreactors (SP‐NRs) can promote reaction kinetics while facilitating rapid polysulfide transformation and minimizing dissolution and diffusion losses. Meanwhile, overall ultrahigh energy input and output are achieved through tandem connection with carbon nanotubes, isolation with PEDOT coating, and synergistic multiplicative effects among SP‐NRs. As a result, it delivers a high initial discharge capacity of 1246 mAh g−1 at 0.1 C and 918 mAh g−1 at 1 C, the low capacity decay rate per lap of 0.011 % is achieved at a current density of 1 C after 1000 cycles. This research emphasizes the innovative structural design to provide a fresh trajectory for the further advancement of high‐performance energy storage devices. [ABSTRACT FROM AUTHOR]

Electrocatalytic C−N couplings are promising alternatives to construct C−N bonds and to synthesize vital chemicals, including amine, amide, amino acid, oxime, imine, and nitrile, under ambient conditions. In recent years, the electrocatalytic C−N coupling has attracted a wide range of research interest and has achieved considerable developments. Here, the electrocatalytic C−N coupling is systematically reviewed aiming at reductive cathode and oxidative anode. In the cathodic part, the electrocatalytic coupling reaction systems, the corresponding design principles of electrocatalysts for different reaction systems, the mechanism studies from experimental and theoretical aspects, and the application‐oriented electrocatalytic devices for electrocatalytic C−N couplings are summarized. Anodic C−N coupling offers a potential approach to replace the conventional energy‐demand synthesis protocols, and is an indispensable part of the green and controllable construction of unsaturated C = N and C≡N bonds. According to the principle that electron transfer is the crucial point in anodic C−N coupling, the anodic coupling reactions are sorted out based on the direct and the indirect C−N coupling paths, respectively. Finally, the challenges and outlooks in this field are proposed. Electrocatalytic C−N coupling is an appealing research topic in electrochemistry and possesses infinite possibilities in the future. [ABSTRACT FROM AUTHOR]

Biofiltration is a method of pollution management that utilizes a bioreactor containing live material to absorb and destroy pollutants biologically. In this paper, we investigate mathematical models of biofiltration for mixing volatile organic compounds (VOCs) for instance hydrophilic (methanol) and hydrophobic (α -pinene). The system of nonlinear diffusion equations describes the Michaelis-Menten kinetics of the enzymic chemical reaction. These models represent the chemical oxidation in the gas phase and mass transmission within the air-biofilm junction. Furthermore, for the numerical study of the saturation of α -pinene and methanol in the biofilm and gas state, we have developed an efficient supervised machine learning algorithm based on the architecture of Elman neural networks (ENN). Moreover, the Levenberg-Marquardt (LM) optimization paradigm is used to find the parameters/ neurons involved in the ENN architecture. The approximation to a solutions found by the ENN-LM technique for methanol saturation and α -pinene under variations in different physical parameters are allegorized with the numerical results computed by state-of-the-art techniques. The graphical and statistical illustration of indications of performance relative to the terms of absolute errors, mean absolute deviations, computational complexity, and mean square error validates that our results perfectly describe the real-life situation and can further be used for problems arising in chemical engineering. [ABSTRACT FROM AUTHOR]

This study investigates the application of quantum mechanical (QM) and multiscale computational methods in understanding the reaction mechanisms and kinetics of SN2 reactions involving methyl iodide with NH2OH and NH2O−, as well as the Claisen rearrangement of 8-(vinyloxy)dec-9-enoate. Our aim is to evaluate the accuracy and effectiveness of these methods in predicting experimental outcomes for these organic reactions. We achieve this by employing QM-only calculations and several hybrids of QM and molecular mechanics (MM) methods, namely QM/MM, QM1/QM2, and QM1/QM2/MM methodologies. For the SN2 reactions, our results demonstrate the importance of explicitly including solvent effects in the calculations to accurately reproduce the transition state geometry and energetics. The multiscale methods, particularly QM/MM and QM1/QM2, show promising performance in predicting activation energies. Moreover, we observe that the size of the MM active region significantly affects the accuracy of calculated activation energies, highlighting the need for careful consideration during the setup of multiscale calculations. In the case of the Claisen rearrangement, both QM-only and multiscale methods successfully reproduce the proposed reaction mechanism. However, the activation free energies calculated using a continuum solvation model, based on single-point calculations of QM-only structures, fail to account for solvent effects. On the other hand, multiscale methods more accurately capture the impact of solvents on activation free energies, with systematic error correction enhancing the accuracy of the results. Furthermore, we introduce a Python code for setting up multiscale calculations with ORCA, which is available on GitHub at https://github.com/iranimehdi/pdbtoORCA. [ABSTRACT FROM AUTHOR]

[4Fe‐4S]‐dependent enzymes catalyze many different types of biological reactions. The quantum chemical cluster approach and the combined quantum mechanics/molecular mechanics approach, with the broken symmetry approach, are powerful tools for understanding the reaction mechanism in enzymes. This review discusses examples of the computational studies on [4Fe‐4S]‐dependent enzymes, focusing on the electron‐transfer driven substrate activation. [ABSTRACT FROM AUTHOR]

The bicarbonate-activated hydrogen peroxide (BAP) system is widely studied for organic pollutant degradation in wastewater treatment. Ca2Co2O5, a heterogeneous catalyst containing multivalent cobalt including Co(II) and Co(III), was herein investigated as a BAP activator, and Acid Orange 7 (AO7) was used as a model pollutant. Ca2Co2O5 exhibited good activation performance. The degradation rate and the initial rate constant of the Ca2Co2O5-activated BAP system were 5.4 and 11.2 times as high as the BAP system, respectively. The removal rate of AO7 reached 90.9% in 30 min under optimal conditions (AO7 20 mg/L, Ca2Co2O5 0.2 g/L, H2O2 1 mM, NaHCO3 5 mM, pH 8.5, 25℃). The Ca2Co2O5 catalyst exhibited good stability and recyclability, retaining 85% of AO7 removal rate in the fifth run. Compared to the BAP system, a lower dosage of H2O2 was required and a higher initial concentration of pollutants allowed for effective degradation in the Ca2Co2O5-BAP system. X-ray photoelectron spectroscopy was used to analyze the catalytic mechanism. The analysis showed that the good catalytic performance of Ca2Co2O5 attributes to its high proportion of oxygen vacancies and Co(III) species, and the presence of Ca. The active species O2•−, •OH, and 1O2 are responsible for the degradation, as indicated by the quenching experiments. The degradation mechanism of AO7 was speculated based on UV–Vis spectral analysis and the identification of degradation intermediates. The azo form, naphthalene and benzoic rings in the AO7 structure are destroyed in the decomposition. This research provides a feasible approach to designing effective and reusable BAP activators for pollutant degradation in wastewater treatment. [ABSTRACT FROM AUTHOR]

Developing highly efficient catalysts for carbon dioxide reduction reaction (CO2RR) is significant in producing useful chemicals and alleviating environmental pollution. Herein, a series of two-dimensional TM-PTC (TM = Sc-Zn, PTC = 1,2,3,4,5,6,7,8,9,10,11,12-perthiolated coronene) frameworks as CO2RR electrocatalysts are investigated based on the density functional method. The calculated results showed that the main product is CH4 for TM-PTC (TM = Sc-Mn). However, these catalysts can be poisoned by water molecules due to its strong adsorption on the catalyst surface. To solve the problem, we modified these catalysts by adding axial oxygen (TM-O-PTC). Our study showed that TM-O-PTC (TM = V, Cr) are good catalysts for CO2RR to produce CH4. We expected that this work could provide a useful strategy for developing high-performance CO2RR electrocatalysts. [ABSTRACT FROM AUTHOR]

Precise electrochemical synthesis of commodity chemicals and fuels from CO21 building blocks provides a promising route to close the anthropogenic carbon cycle, in which renewable but intermittent electricity could be stored within the greenhouse gas molecules. Here, we report state-of-the-art CO2-to-HCOOH valorization performance over a multiscale optimized Cu-Bi cathodic architecture, delivering a formate Faradaic efficiency exceeding 95% within an aqueous electrolyzer, a C-basis HCOOH purity above 99.8% within a solid-state electrolyzer operated at 100 mA cm-2 for 200 h and an energy efficiency of 39.2%, as well as a tunable aqueous HCOOH concentration ranging from 2.7 to 92.1 wt%. Via a combined two-dimensional reaction phase diagram and finite element analysis, we highlight the role of local geometries of Cu and Bi in branching the adsorption strength for key intermediates like *COOH and *OCHO for CO2 reduction, while the crystal orbital Hamiltonian population analysis rationalizes the vital contribution from moderate binding strength of η²(O,O)-OCHO on Cu-doped Bi surface in promoting HCOOH electrosynthesis. The findings of this study not only shed light on the tuning knobs for precise CO2 valorization, but also provide a different research paradigm for advancing the activity and selectivity optimization in a broad range of electrosynthetic systems. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF) degradation in aqueous solution under electron beam (EB) irradiation after nanobubbling treatment was studied and compared with treatments using nanobubbling or EB irradiation alone. It was found that the removal efficiency of DCF increased by increasing the adsorbed dose, and it depended on the initial concentration of DCF in solution, being higher for the lower concentrations. Furthermore, when using the nanobubbling treatment alone, about 16% of the DCF was removed from the aqueous solution due to the OH radicals generated during the process. On the other hand, using EB treatment at 0.5 kGy, the degradation of DCF increased from 36% to 51% when adding a nanobubbling pretreatment before the EB radiation. At higher doses (5 kGy), the degradation of DCF was 96% using EB radiation and 99% using nanobubbling before EB radiation, indicating that the nanobubbling effect was not synergistic. With an increase in the adsorbed doses, EB radiation seemed to play a more important role on the degradation of DCF, probably due to the reactive species generated. Moreover, the solutions treated with nanobubbling and EB radiation presented higher COD values and radiolytic by-products with aromatic rings with chlorine. This work can support the development of innovative strategies to treat municipal wastewaters using ionizing radiation technologies. [ABSTRACT FROM AUTHOR]

A well-defined substrate with an array of capillaries was infiltrated at a temperature of 1223 K, a pressure of 40 kPa and a residence time of 0.56 s. After 75 h deposition, the thickness of pyrolytic carbon layer in the capillary was determined along its depth. By coupling a detailed gas-phase reaction mechanism with the parallel-consecutive reaction model, the pyrolytic carbon deposition from propylene pyrolysis was accurately simulated within capillaries. From the simulated results, it was observed that pore sealing could be relieved by reducing residence time. The texture of pyrolytic carbon at the mouth of the capillary was also determined. In addition, Kinetic Monte Carlo simulations were used to analyze how residence time and substrate surface affect the transition in texture of pyrolytic carbon. According to these calculations, it appears that texture is mainly affected by interactions between residence time and active sites on the substrate surface. [ABSTRACT FROM AUTHOR]

Aluminium is one of the most abundant metals in the universe and impacts the evolution of various astrophysical environments. Currently detected Al‐bearing molecules represent only a small fraction of the aluminium budget, suggesting that aluminium may reside in other species. AlO and AlOH molecules are abundant in the oxygen‐rich supergiant stars such as VY Canis Majoris, a stellar molecular factory with 60+ molecules including the prebiotic NC‐bearing species. Additional Al‐bearing molecules with N, C, O, and H may form in O‐rich environments with radiation‐accelerated chemistry. Here, we present spectroscopic identification of novel aluminium‐bearing molecules composed of [Al, N, C, O, H] and [Al, N, C, O] from the reactions of Al atoms and HNCO in solid argon matrix, which are potential Al‐bearing molecules in space. Photoinduced transformations among six [Al, N, C, O, H] isomers and three [Al, N, C, O] isomers, along with their dissociation reactions forming the known interstellar species, have been disclosed. These results provide new insight into the chemical network of astronomically detected Al‐bearing species in space. [ABSTRACT FROM AUTHOR]

Aryl bromides and 4‐chlorotoluene as an example aryl chloride in the presence of N‐heterocyclic carbene (NHC) palladium hydroxo dimers of the type [{Pd(μ‐OH)Cl(NHC)}2] (where NHC=IPr, SIPr, IMes, SIMes) undergo an efficient and selective Sonogashira cross‐coupling with (hetero)arylacetylenes. The procedure allows the high‐throughput and selective synthesis of a broad spectrum of 1,2‐diarylacetylenes using 10 ppm of [{Pd(μ‐OH)Cl(IPr)}2] as precatalyst. For the coupling of 4‐chlorotoluene with phenylacetylene, TON=560000 was achieved. Hydrogen chloride was observed as a product of the Sonogashira cross‐coupling reaction. The formation of the active Pd(0) from the Pd(II) complex was found to proceed via ethanol oxidation. Mechanistic studies showed that water plays a key role in the reaction. [ABSTRACT FROM AUTHOR]

A comprehensive study of the different classes of cycloaddition reactions ([3+2], [2+2], and [2+1]) of SO2 to acetylene and ethylene has been performed using density functional theory (DFT) and composite wavefunction methods. The [3+2] cycloaddition reaction, that was previously explored in the context of the cycloaddition of thioformaldehyde S‐methylide (TSM) to ethylene and acetylene, proceeds in a concerted way to the formation of stable heterocycles. In this paper, we extend our study to the [2+2] and [2+1] cycloadditions of SO2 to acetylene, which would produce 1,1‐oxathiete‐2‐oxide and thiirene‐1,1‐dioxide, respectively. One of the main conclusions is that cyclic 1,1‐oxathiete‐2‐oxide can open through a relatively easy breaking of the SO single bond and rearrange toward sulfinyl acetaldehyde (SA). The SA molecule can easily undergo several internal rearrangements, which eventually lead to sulfenic acid and sulfoxide derivatives of ethenone, 1,2,3‐dioxathiole, and CO plus sulfinylmethane. The most probable path, however, produces 2‐thioxoacetic acid, whose derivatives (or those of the corresponding acetate) are usually obtained by Willgerodt–Kindler‐type sulfuration of acetates. This product can in turn decompose, leading to the final products CO2 and H2CS. Comparison of this decomposition path with that of 2‐amino‐2‐thioxoacetic acid shows that the process occurs through different H‐transfer processes. [ABSTRACT FROM AUTHOR]

Due to the frequent detection and potential toxicity of moxifloxacin (MOX), its removal technology had attracted attention in recent years. In this research, CuFeS2/MXene was prepared and used to activate peroxymonosulfate (PMS) to remove MOX. The degradation efficiencies, kinetics, influences, and reaction mechanism of MOX by CuFeS2/MXene/PMS were investigated. The synergistic effect of CuFeS2 and MXene significantly enhanced PMS activation, producing SO4•–, HO•, and 1O2 as the main active species. By adding 0.12 g/L CuFeS2/MXene and 0.12 mM PMS, MOX removal efficiency reached 99.1% within 40 min, with a rate constant of 0.1073 min−1. The composite ratios of CuFeS2/MXene impacted PMS activation more significantly than catalyst dosages and PMS concentrations. Acidic conditions were favorable for the degradation of MOX, while HCO3–, HPO42−, Mn2+, and HA had the inhibitory effects. Twelve major products were detected by HPLC–MS, and DFT was used to illustrate possible degradation pathways of MOX, including the removal of nitrogen-containing heterocycle and transformations of quinolone moieties. Toxicity analysis showed that the developmental toxicity, mutagenicity, and acute toxicity of degradation products tended to decrease. CuFeS2/MXene could exhibit excellent reusability, maintaining an average MOX degradation efficiency of 90.8% in the 7-cycle experiments. [ABSTRACT FROM AUTHOR]

The boracarboxylation reaction has potential for the production of natural products and drug candidates, but the development of an asymmetric version of this transformation is challenging. We report an enantioselective boracarboxylation of styrenes, enabled by a copper catalyst containing chiral phosphines. Our experimental conditions provide yields between 31–76% and enantiomeric ratios from 80:20 up to 98:2 for electron‐rich styrenes. Oxidation of a boracarboxylation product gives (S)‐tropic acid, an intermediate towards several tropane alkaloids. A computational analysis of the mechanistic details shows a complex pattern of competing reaction pathways, highlighting challenges encountered when developing asymmetric reactions using CO2. [ABSTRACT FROM AUTHOR]

This study focuses on optimizing the synthesis of ZnO/Kaolin nanoparticles and their application in adsorptive bleaching of palm oil. The reaction mechanism involves the dissolution of metal oxides (Fe2O3, Al2O3, CaO, MgO) from clay lattices using mineral acids, increasing the surface area and triggering ion exchange processes. The kaolin is beneficiated through crushing, washing, acid treatment, and drying, and then activated with ZnCl2. Zinc oxide nanoparticles are synthesized using Moringa leaf extract and zinc acetate, followed by the synthesis of ZnO/Kaolin composites using Central Composite Design (CCD) to optimize parameters like kaolin ratio, calcination temperature, and time. The composites are characterized by XRD, XRF, and BET surface area analysis. The bleaching efficiency is evaluated through absorbance and iodine value, with ANOVA analysis confirming the significance of dosage, temperature, and time. The optimized conditions identified are essential for maximizing the composite’s adsorptive efficiency in palm oil bleaching. [ABSTRACT FROM AUTHOR]

Poly(ADP-ribose) polymerase 1 (PARP1) plays a major role in the DNA damage repair and transcriptional regulation, and is targeted by a number of clinical inhibitors. Despite this, catalytic mechanism of PARP1 remains largely underexplored because of the complex substrate/product structure. Using molecular modeling and metadynamics simulations we have described in detail elongation of poly(ADP-ribose) chain in the PARP1 active site. It was shown that elongation reaction proceeds via the SN1-like mechanism involving formation of the intermediate furanosyl oxocarbenium ion. Intriguingly, nucleophilic 2′A-OH group of the acceptor substrate can be activated by the general base Glu988 not directly but through the proton relay system including the adjacent 3′A-OH group. [ABSTRACT FROM AUTHOR]

When synthesizing the versatile precursors (NMe4)[Ni(CF3)3(MeCN)] we recently encountered the problem that marked amounts of C2F5 were incorporated instead of CF3 under the chosen reaction conditions forming mixed-ligand nickelates [Ni(CF3)x(C2F5)y(MeCN)]− (x + y = 3). We studied the three products with y = 0, 1, or 2, using 19F nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray diffraction. We were able to trace the reaction mechanism and solve the problem by modifying the experimental conditions. [ABSTRACT FROM AUTHOR]

Industrially, petroleum naphtha reforming and steam cracking are two major multistep and energy-intensive sources for p-xylene production. Additionally, p-xylene is also produced by selective toluene disproportionation, heavy (C9) aromatics trans-alkylation and isomerization of xylenes. Rapidly changing market dynamics from fuels to petrochemicals coupled with growing petrochemicals demand has led to the further exploration of economical and highly p-xylene selective processes by using surplus low-value aromatics. Methylation of toluene with methanol has been envisaged as one such potential opportunity to produce p-xylene. For the purpose, significant efforts have been made in the past forty years to develop suitable shape selective zeolite catalysts and technologies to make toluene methylation a highly p-xylene selective process. Current paper briefly highlights various advancements in the toluene methylation process development and aims to provide an extensive review of several works put up in the past to design suitable catalysts, catalyst's limitations and developmental challenges for toluene methylation. Further, this paper provides an useful insight for two competing chemistries of toluene alkylation and side-by-side methanol reactions. Finally, motivated by competitive chemistry of methanol conversion reactions, existing catalytic limitations and novel synthesis opportunities in engineering shape selective zeolite catalysis, a way forward is proposed to arrive at a logical and futuristic catalyst design strategy for p-xylene production via toluene methylation. The proposed strategy is envisaged to offer low-to-moderate catalyst acidity, improved toluene methylation activity, high p-xylene selectivity and improved catalyst life which, otherwise, up till now have been the bottlenecks to develop distinctly economical toluene alkylation to p-xylene process. [ABSTRACT FROM AUTHOR]

The conversion of CO2 into fuels and value-added chemicals over heterogeneous catalysts may help realize a carbon-neutral or carbon-negative society. Recently, the direct conversion of CO2 to aromatics has been extensively explored. However, the requirement of multifunctional active sites, complexity of tandem cascade reactions, and difficulty in understanding reaction mechanisms present significant challenges to the design of effective heterogeneous catalysts. In this review, catalytic systems used for the direct production of aromatics from CO2 via the methanol-mediated and modified Fischer–Tropsch synthesis pathways are critically discussed. The initial section discusses the role of acid sites in HZSM-5 for the formation of aromatics. This is followed by a thorough review of recent progress on aromatic syntheses in terms of their catalytic performance, Si/Al ratios of zeolites, proximity between metal oxide and zeolite, and reaction conditions. The reaction mechanisms and the stability of existing catalysts are also discussed. Finally, the current challenges and future prospects of the catalytic conversion of CO2 to aromatics are highlighted. [ABSTRACT FROM AUTHOR]

Studies have shown that the incorporation of fluorine into materials can improve their properties, but C–F bonds are not readily formed in nature. Although some researchers have studied the reaction of fluorinating alkenes catalyzed by hypervalent iodine, far too little attention has been paid to its reaction mechanism. This study aimed to explore the mechanism of the hypervalent iodine-catalyzed 1,4-difluorination of dienes. We found that the catalyst is favorable for the activation of C1=C2 double bonds through halogen bonds, and then two HFs interact with one F atom in the catalyst via hydrogen bonds, resulting in the cleavage of I–F bonds and the formation of [F–H∙∙∙F]−. Subsequently, the catalyst interacts with C1, and the roaming [F–H···F]− attacks C4 from the opposite side of the catalyst. After the fluorination step is completed, the nucleophile F− substitutes the catalyst via the SN2 mechanism. Our calculations demonstrated that the interaction between HF and F− is favorable for the stabilization of the transition state within the fluorination process for which the presence of two HFs in the reaction is the best. We also observed that [F–H∙∙∙F]− attacking C4 from the opposite side of the catalyst is more advantageous than attacking from the same side. This study therefore offers a novel perspective on the mechanism of the hypervalent iodine-catalyzed fluoridation of dienes. [ABSTRACT FROM AUTHOR]

The technology for the selective catalytic reduction of NOx by CO (CO-SCR) has the capability to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, thus making it a promising denitrification method. The advancement of cost-effective and high-performing catalysts is crucial for the commercialization of this technology. Mn-based catalysts demonstrate enhanced catalytic efficiency under conditions of low temperature and low oxygen content when compared to other transition metal-based catalysts, indicating significant potential for practical applications. This review outlines the diverse Mn-based catalysts, including bulk or supported MnOx catalysts, bulk or supported Mn-based composite oxide catalysts, and the use of MnOx as dopants. Subsequently, the synthesis methods and catalytic mechanism employed by Mn-based catalysts are presented. The following section examines the impact of O2, H2O, and SO2 on the catalytic performance. Finally, the potential and implications of this reaction are deliberated. This work aims to offer theoretical guidance for the rational design of highly efficient Mn-based catalysts in the CO-SCR reaction for industrial applications. [ABSTRACT FROM AUTHOR]