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The reaction chemistry and degradation mechanism of MnO2‐based cathodes remain controversial, which hinder their applications in energy storage. Herein, a conversion reaction between Zn4SO4·(OH)6·nH2O (ZSH) and ZnxMnO(OH)2 (ZMO) is proposed in ZnSO4‐based electrolytes. The conversion reaction is an important component of the reaction chemistry as well as the Zn2+/H+ intercalation/deintercalation reaction, which not only provides electrochemical capacity but also dominates the degradation of MnO2 cathodes. The massive accumulation of inactive ZMO seriously destroying the dynamic performance of MnO2 cathodes is deemed to be a principal trigger of the degradation mechanism. Intriguingly, the conversion reaction is sensitive to voltage, which can be activated by voltage modulation. Active ZMO generated in the activated conversion reaction is endowed with higher reversibility and electrooxidation, avoiding the accumulation of inactive ZMO and the decline of kinetic performance, which are evidenced by MnO2 and ZSH cathodes. Accordingly, superior cycling stability with a capacity retention of 89.1% after 2000 cycles is achieved at 2 A g−1 for the MnO2 cathode equipped with the activated conversion reaction. Impressively, the conversion reaction activated by voltage modulation is applicable to various crystal forms of MnO2 (α‐, β‐, γ‐, δ‐), which is significant for the ZIBs with a long lifespan. [ABSTRACT FROM AUTHOR]

The enzymatic biosynthesis of fragrance molecules from lignin fragments is an important reaction in biotechnology for the sustainable production of fine chemicals. In this work we investigated the biosynthesis of vanillin from lignostilbene by a nonheme iron dioxygenase using QM/MM and tested several suggested proposals via either an epoxide or dioxetane intermediate. Binding of dioxygen to the active site of the protein results in the formation of an iron(II)−superoxo species with lignostilbene cation radical. The dioxygenase mechanism starts with electrophilic attack of the terminal oxygen atom of the superoxo group on the central C=C bond of lignostilbene, and the second‐coordination sphere effects in the substrate binding pocket guide the reaction towards dioxetane formation. The computed mechanism is rationalized with thermochemical cycles and valence bond schemes that explain the electron transfer processes during the reaction mechanism. Particularly, the polarity of the protein and the local electric field and dipole moments enable a facile electron transfer and an exergonic dioxetane formation pathway. [ABSTRACT FROM AUTHOR]

The nonheme iron dioxygenase deoxypodophyllotoxin synthase performs an oxidative ring-closure reaction as part of natural product synthesis in plants. How the enzyme enables the oxidative ring-closure reaction of (-)-yatein and avoids substrate hydroxylation remains unknown. To gain insight into the reaction mechanism and understand the details of the pathways leading to products and by-products we performed a comprehensive computational study. The work shows that substrate is bound tightly into the substrate binding pocket with the C7'-H bond closest to the iron(IV)-oxo species. The reaction proceeds through a radical mechanism starting with hydrogen atom abstraction from the C7'-H position followed by ring-closure and a final hydrogen transfer to form iron(II)-water and deoxypodophyllotoxin. Alternative mechanisms including substrate hydroxylation and an electron transfer pathway were explored but found to be higher in energy. The mechanism is guided by electrostatic perturbations of charged residues in the second-coordination sphere that prevent alternative pathways. [ABSTRACT FROM AUTHOR]

Obtaining a rapid deflagration-to-detonation transition (DDT) within a short smooth tube is a challenging task. Here, an unconventional means of flame acceleration propagating upstream in subsonic and supersonic mixtures within a smooth tube was introduced to acquire a speedy DDT. The Navier–Stokes equations with an adaptive mesh refinement technique and a detailed hydrogen–air chemistry reaction mechanism of 11 species and 27 steps were utilized to resolve the entire DDT characteristics. The effect of the initial Mach number on flame acceleration and DDT mechanism was revealed comprehensively. The results demonstrated that a prompt oblique shock wave (SW) occurs when the flame propagates upstream along the boundary walls due to the boundary layer influence. An intense coupling between the SW and the leading flame front is enhanced by increasing the initial Mach number of the mixture. The speedy generation of the oblique SW is formed at the incipient stage, mainly produced by the boundary layer influence and the coalescences of the compression waves. Consequently, the run-up time to detonation is shortened accordingly through a fierce reflected SW due to the intense leading SW after it reflects from the confined wall. Furthermore, three kinds of DDT evolution are revealed from the obtained results: (1) localized ignition in the upper boundary wall after the reflected and transverse shock waves propagate in the upper wall regions; (2) autoignition is formed in the confined wall corner after the reflected SW; and (3) direct detonation transition occurs at the end wall behind a strongly reflected SW in the supersonic case. [ABSTRACT FROM AUTHOR]

As high-energy cathode materials, conversion-type metal fluorides provide a prospective pathway for developing next-generation lithium-ion batteries. However, they suffer from severe performance decay owing to continuous structural destruction and active material dissolution upon cycling, which worsen at elevated temperatures. Here, we design a novel FeF2 cathode with in situ polymerized solid-state electrolyte systems to enhance the cycling ability of metal fluorides at 60 °C. Novel FeF2 with a mesoporous structure (meso-FeF2) improves Li+ diffusion and relieves the volume change that typically occurs during the alternating conversion reactions. The structural stability of the meso-FeF2 cathode is strengthened by an in situ polymerized solid-state electrolyte, which prevents the pulverization and ion dissolution that are inevitable for conventional liquid electrolytes. Under the double action of this in situ polymerized solid-state electrolyte and the meso-FeF2's mesoporous structure, the active material maintains an intact SEI layer and part of the mesoporous structure after long charge-discharge cycling, showing excellent cycling stability at high temperatures. [ABSTRACT FROM AUTHOR]

The presented Review is focused on the latest research in the field of inorganic chemistry performed by the van Eldik group and his collaborators. The first part of the manuscript concentrates on the interaction of nitric oxide and its derivatives with biologically important compounds. We summarized mechanistic information on the interaction between model porphyrin systems (microperoxidase) and NO as well as the recent studies on the formation of nitrosylcobalamin (CblNO). The following sections cover the characterization of the Ru(II)/Ru(III) mixed‐valence ion‐pair complexes, including Ru(II)/Ru(III)(edta) complexes. The last part concerns the latest mechanistic information on the DFT techniques applications. Each section presents the most important results with the mechanistic interpretations. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is a versatile reductant that under the right conditions can react to form dioxygen in an electrochemical reaction. This reaction has a low carbon footprint and applications are being sought for batteries. In this work a computational study is presented on a recently reported nonheme iron(II) complex where we study mechanistic pathways leading to dioxygen formation from H2O2. The work shows that upon reduction of the iron(III)‐hydroperoxo species it rapidly leads through heterolytic cleavage of the dioxygen bond to form iron(IV)‐oxo(hydroxo). The dimerization reaction of two iron(IV)‐oxo(hydroxo) complexes then leads to formation of the dioxygen bond rapidly with small barriers. Dissociation of the dimer expels dioxygen in an exothermic reaction. An alternative mechanism through the formation of a μ‐1,2‐peroxo‐μ‐1,1‐hydroperoxodiiron(II) intermediate was also tested but found to be highly endergonic. These studies highlight the electrochemical feasibilities of nonheme iron(III)‐hydroperoxo complexes. [ABSTRACT FROM AUTHOR]

Highlights: Detailed discussion and summary of aqueous electrolyte chemistry, parasitic reactions chemistry, and storage energy chemistry and their relationship in aqueous zinc ions batteries are conducted. The recent development of strategies for enhancing the inherent stability of electrolyte and zinc anode to restrain parasitic reactions is reviewed from a thermodynamic perspective. The regulation strategies of electrolyte/electrode interfaces to block parasitic reactions by adsorbents and solid electrolyte interphase are reviewed from a kinetic perspective. Based on the attributes of nonflammability, environmental benignity, and cost-effectiveness of aqueous electrolytes, as well as the favorable compatibility of zinc metal with them, aqueous zinc ions batteries (AZIBs) become the leading energy storage candidate to meet the requirements of safety and low cost. Yet, aqueous electrolytes, acting as a double-edged sword, also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side. These reactions include hydrogen evolution reaction, passivation, and dendrites, resulting in poor Coulombic efficiency and short lifespan of AZIBs. A comprehensive review of aqueous electrolytes chemistry, zinc chemistry, mechanism and chemistry of parasitic reactions, and their relationship is lacking. Moreover, the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough. In this review, firstly, the chemistry of electrolytes, zinc anodes, and parasitic reactions and their relationship in AZIBs are deeply disclosed. Subsequently, the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes, and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed. Lastly, the perspectives on the future development direction of aqueous electrolytes, zinc anodes, and Zn/electrolyte interfaces are presented. [ABSTRACT FROM AUTHOR]

CO2 utilization is an important process in the chemical industry with great environmental power. In this work we show how CO2 and H2 can be reacted to form methanol on an iron(II) center and highlight the bottlenecks for the reaction and what structural features of the catalyst are essential for efficient turnover. The calculations predict the reactions to proceed through three successive reaction cycles that start with heterolytic cleavage of H2 followed by sequential hydride and proton transfer processes. The H2 splitting process is an endergonic process and hence high pressures will be needed to overcome this step and trigger the hydrogenation reaction. Moreover, H2 cleavage into a hydride and proton requires a metal to bind hydride and a nearby source to bind the proton, such as an amide or pyrazolyl group, which the scorpionate ligand used here facilitates. As such the computations highlight the non‐innocence of the ligand scaffold through proton shuttle from H2 to substrate as an important step in the reaction mechanism. [ABSTRACT FROM AUTHOR]

Aromaticity, in general, can promote a given reaction by stabilizing a transition state or a product via a mobility of π electrons in a cyclic structure. Similarly, such a promotion could be also achieved by destabilizing an antiaromatic reactant. However, both aromaticity and transition states cannot be directly measured in experiment. Thus, computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms. In this review, we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity. Specifically, we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation, C–F bond activation, rearrangement, as well as metathesis reactions. In addition, antiaromaticity-promoted dihydrogen activation, CO2 capture, and oxygen reduction reactions will be also briefly discussed. Finally, caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases. Thus, a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states. [ABSTRACT FROM AUTHOR]

High‐valent metal‐oxo species play critical roles in enzymatic catalysis yet their properties are still poorly understood. In this work we report a combined experimental and computational study into biomimetic iron(IV)‐oxo and iron(III)‐oxo complexes with tight second‐coordination sphere environments that restrict substrate access. The work shows that the second‐coordination sphere slows the hydrogen atom abstraction step from toluene dramatically and the kinetics is zeroth order in substrate. However, the iron(II)‐hydroxo that is formed has a low reduction potential and hence cannot do OH rebound favorably. The tolyl radical in solution then reacts further with alternative reaction partners. By contrast, the iron(IV)‐oxo species reacts predominantly through OH rebound to form alcohol products. Our studies show that the oxidation state of the metal influences reactivities and selectivities with substrate dramatically and that enzymes will likely need an iron(IV) center to catalyze C−H hydroxylation reactions. [ABSTRACT FROM AUTHOR]

High‐valent iron(IV)‐oxo intermediates are versatile oxidants in the biotransformation of various substrates by metalloenzymes and catalyze essential reactions for human health as well as in the biodegradation of toxic organic pollutants in the environment. Herein, we report a biomimetic system that efficiently reacts with halophenols through defluorination reactions and characterize various short‐lived intermediates along the reaction mechanism. We study the reactivity pattern of a nonheme iron(IV)‐oxo species with a series of trihalophenols (X=F, Cl, Br). A combined experimental and computational study reveals that the oxidative dehalogenation of 2,4,6‐trifluorophenol is initiated with an H‐atom abstraction from the phenolic group by the iron(IV)‐oxo species resulting in the formation of a phenolate radical and an iron(III)‐hydroxo species. This iron(III)‐hydroxo species forms an adduct with the oxidized substrate with λmax at 558 nm which subsequently decays to give quinones as products. [ABSTRACT FROM AUTHOR]

Bioorthogonal chemistry involves selective biocompatible reactions between functional groups that are not normally present in biology. It has been used to probe biomolecules in living systems, and has advanced biomedical strategies such as diagnostics and therapeutics. In this review, the challenges and opportunities encountered when translating in vitro bioorthogonal approaches to in vivo settings are presented, with a focus on methods to deliver the bioorthogonal reaction components. These methods include metabolic bioengineering, active targeting, passive targeting, and simultaneously used strategies. The suitability of bioorthogonal ligation reactions and bond cleavage reactions for in vivo applications is critically appraised, and practical considerations such as the optimum scheduling regimen in pretargeting approaches are discussed. Finally, we present our own perspectives for this area and identify what, in our view, are the key challenges that must be overcome to maximise the impact of these approaches. [ABSTRACT FROM AUTHOR]

Context: The Maillard reaction is a high-temperature reaction of amino acids and carbohydrates to produce macromolecular substances such as melanoidins and intermediate reducing ketones, aldehydes, and volatile compounds. At present, only very limited researches involved the reaction mechanisms of Maillard reaction, which causes a lot of confusion in understanding numerous food processes. The detailed calculations of Maillard reaction are urgently needed. Methods: The density functional theory (DFT) method (M06-2X/6-311G*) was used to deeply explore the specific mechanism of the primary and intermediate stages of Maillard reaction for a selected model system. Results: The results show that the basic reaction processes in primary stage are the formation of Schiff-base by the condensation of amino and carbonyl groups, and then, Schiff-base tautomerization twice through proton transfer to generate Amadori rearrangement products. In the intermediate stage, two main reaction paths, 1-2 and 2-3 enolization, were comprehensively investigated. The first route finally generates 5-hydroxymethylfurfural through isomerization, dehydration, hydrolysis, elimination, and condensation, and the second route products dicarbonyl compounds through isomerization and elimination and then Strecker degradation forms aldehydes through condensation, decarboxylation, hydrolysis, and elimination. The results show that both paths are involved in complex reactions, some are lower barrier reactions, and some higher barrier reactions. An important aspect is that water catalysis is critical in all of these reactions; it is present in most processes. Our study deepens the understanding of the Maillard reaction from molecular level and facilitate the regulation of some harmful products. [ABSTRACT FROM AUTHOR]

• After adding 5 ppm oxygen, the activity is increased to 2.38×106 g·(mol Cr·h)−1. • The amount of polyethylene is significantly reduced after introducing oxygen. • Possible reaction mechanisms of oxygen with TMA and MMAO are proposed through NMR. • Oxygen can react with TMA and MMAO to form lager oligomers and oxidized oligomers. • The oxidation MMAO affected the catalytic species of catalyst system. We have investigated the effect of oxygen on ethylene oligomerization activity and selectivity toward 1-hexene (1-C 6) and 1-octene (1-C 8) using Cr(III) diphosphine catalyst system. The addition of a small amount of oxygen (5 ppm) can improve the activity from 1.75×106 g·(mol Cr·h)−1 to as much as 2.38×106 g·(mol Cr·h)−1, greatly reducing the amount of polyethylene from 1.88 wt% to 0.59 wt%, and maintaining the overall selectivity of 1-C 6 and 1-C 8. The variation trend of the system performance with temperature and n (Al)/ n (Cr) was basically the same before and after. The maximum activity of oxygen modified MMAO activated system reached 2.14×106 g·(mol Cr·h)−1. Through the analysis of NMR and UV–vis DRS results, oxygen mainly reacts with MMAO or residual TMA to produce larger steric bulk oligomers and oxidized oligomers. The larger oligomers resulting in more steric hindrance around the active Cr species, disfavor the attack of impurity small molecules and long chain molecules on the active center, thereby inhibiting the reaction inactivation and the PE formation. The modification MMAO affected the catalyst species, which may also affect the catalyst performance, especially at high O 2 concentration. [Display omitted] [ABSTRACT FROM AUTHOR]

• A theoretical study of the structure, electronic, and reaction mechanism of CO 2 to methanol on In 3 Ru(212) surfaces with different surface In/Ru ratio. • In 3 Ru could achieve high methanol selectivity by adding a H 2 O into each elementary step because it benefits the O H formation process. Designing high-performance catalyst is vital in the field of CO 2 methanolization. In this study, two In 3 Ru surfaces (In 3 Ru_i and In 3 Ru_r) were employed as computational models and the density functional theory was applied to study the influence of surface In/Ru ratio on their surface morphologies, reaction mechanisms and catalysis performance for methanol synthesis. Surface characterization reveals that In 3 Ru_i is higher in surface In/Ru ratio than In 3 Ru_r, and such difference facilitates CO 2 adsorption on In 3 Ru_r. Being different in surface In/Ru ratio, two surfaces exhibit distinct variations in the reaction mechanism of methanol formation. For In 3 Ru_i, the "Formate" pathway dominates the first CO 2 activation step which leads to methanol production. On the other hand, In 3 Ru_r prefers the "reverse water-gas shift" pathway (RWGS) in the initial step of CO 2 activation, but this mechanism is unable to generate CH 3 OH due to the kinetic limitation of CO* hydrogenation. Based on the microkinetic modeling, In 3 Ru_i is superior in both CO 2 production rate and CH 3 OH selectivity than the other one, suggesting higher surface In/Ru ratio benefits methanol formation, which complies well with the experiment. Overall, our study offers a new perspective with respect to how surface morphology of the bimetallic catalyst influences the reaction mechanisms of CO 2 hydrogenation. [Display omitted] [ABSTRACT FROM AUTHOR]

A kinetic study is reported for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (1a–1f) and Y-substituted-phenyl benzenesulfonates (2a–2f) with Z-substituted-pyridines. The reactions proceed through S–O and C–O bond scissions competitively. The Yukawa–Tsuno plot for the reactions of 1a–1f with 4-oxypyridine (S–O bond fission) exhibits an excellent linearity. The Brønsted-type plot for the reactions of 2,4-dinitrophenyl benzenesulfonate (1d) with pyridines (S–O bond fission) is also linear with βnuc = 0.62. The Brønsted-type plot for the reactions of 2a–2f with 4-oxypyridines (S–O bond fission) is linear with βlg = –1.17. Thus, the reactions have been concluded to proceed through a concerted mechanism, in which leaving-group expulsion is significantly more advanced than bond formation between the electrophilic center and nucleophile at the transition state. The Hammett plot for the reactions of 1a–1f with 4-oxypyridine (C–O bond fission) exhibits scattered points with ρX = 0.98. The Brønsted-type plot for the reactions of 1d with Z-substituted-pyridines (C–O bond fission) results in an excellent linear correlation with βnuc = 0.38. Thus, the reactions (C–O bond fission) have been concluded to proceed through a stepwise mechanism with a Meisenheimer complex, in which expulsion of the leaving group occurs after the rate-determining step. Factors governing regioselectivity and reaction mechanism are discussed. [ABSTRACT FROM AUTHOR]

This work presents a new CFD model developed to investigate the SiC film growth over a fuel combustion nozzle in the commercial hot-wall CVD reactor. A detailed 3D model consisting of the compressive transport models and the reaction mechanism to account for the chemistry of the gas-phase and surface reactions are developed. The velocity, temperature, and concentration profiles inside the reactor are predicted numerically. The multispecies transport and its interplay with the gas and surface reactions are understood to operate the reactor effectively. The natural convection and hydrodynamics stability of the flow is investigated using various dimensionless groups (Re, Pr. Pe, and Gr/Re2). It has been observed that the buoyancy-driven flow is dominant at a large Reynolds number (Re) and Gr/Re2 ratio. This results in flow recirculation, which ultimately deteriorates the film uniformity. A sensitivity analysis is performed to identify how critical parameters affect the deposition process. Besides, the optimisation of the CVD reactor is also served by combining the support vector machine, a versatile supervised machine learning method, and the Nelder-Mead algorithm to improve the film quality. Our results demonstrate that the present methodology effectively obtains optimal process conditions, significantly enhancing the film performance. [ABSTRACT FROM AUTHOR]

The chelator-mediated Fenton (CMF) chemistry is one of the main biological non-enzymatic systems for oxygen-centered radical generation. A perhydroxyl radical (HO2˙) is a secondary radical specie in CMF systems, however, despite being reported as an iron reducer, its production and role in the CMF redox chemistry are not yet well understood. We assessed the production profiles of HO2˙ and HO˙ generated in situ in CMF systems by EPR, iron-reducing capacity with and without HO2˙, and ligand concentration using CMF systems with p-substituted catecholates between pH values 3.0 and 7.0. The results showed that HO2˙ was generated as a secondary radical in all CMF systems but it also showed evidence of a HO2˙-independent pathway that contributes to the reduction of Fe3+. Along with the current knowledge of the reaction mechanism of the CMF chemistry, the SQ˙ of the ED ligand is proposed to contribute to the generation of HO2˙. [ABSTRACT FROM AUTHOR]

Organic chemistry (OC) appears to be an unstructured and confusing subject to many learners. Reaction mechanisms often seem to be an additional challenge rather than a helpful guideline. Comparable problems were also found for OC as a science at the beginning of the 20th century. One turning point was the systematic application of physical principles on organic reactions through Ingold and coworkers. Kinetic measurements implied for example that in nucleophilic substitution reactions the elimination of the leaving group and the attack of the nucleophile could either occur at the same time or stepwise. In this work the historic insights are made accessible for school lessons by easy experiments suitable for school students. A fictional audio diary of Hilda Ingold is proposed as a history lift to make learners realize that in principle different reaction pathways are possible for one reaction type. [ABSTRACT FROM AUTHOR]

Taurine/α‐ketoglutarate dioxygenase is an important enzyme that takes part in the cysteine catabolism process in the human body and selectively hydroxylates taurine at the C1‐position. Recent computational studies showed that in the gas‐phase the C2−H bond of taurine is substantially weaker than the C1−H bond, yet no evidence exists of 2‐hydroxytaurine products. To this end, a detailed computational study on the selectivity patterns in TauD was performed. The calculations show that the second‐coordination sphere and the protonation states of residues play a major role in guiding the enzyme to the right selectivity. Specifically, a single proton on an active site histidine residue can change the regioselectivity of the reaction through its electrostatic perturbations in the active site and effectively changes the C1−H and C2−H bond strengths of taurine. This is further emphasized by many polar and hydrogen bonding interactions of the protein cage in TauD with the substrate and the oxidant that weaken the pro‐R C1−H bond and triggers a chemoselective reaction process. The large cluster models reproduce the experimental free energy of activation excellently. [ABSTRACT FROM AUTHOR]

Aryloxyalkanoate dioxygenases are unique herbicide biodegrading nonheme iron enzymes found in plants and hence, from environmental and agricultural point of view they are important and valuable. However, they often are substrate specific and little is known on the details of the mechanism and the substrate scope. To this end, we created enzyme models and calculate the mechanism for 2,4‐dichlorophenoxyacetic acid biodegradation and 2‐methyl substituted analogues by density functional theory. The work shows that the substrate binding is tight and positions the aliphatic group close to the metal center to enable a chemoselective reaction mechanism to form the C2‐hydroxy products, whereas the aromatic hydroxylation barriers are well higher in energy. Subsequently, we investigated the metabolism of R‐ and S‐methyl substituted inhibitors and show that these do not react as efficiently as 2,4‐dichlorophenoxyacetic acid substrate due to stereochemical clashes in the active site and particularly for the R‐isomer give high rebound barriers. [ABSTRACT FROM AUTHOR]

This rosarium article relates the adventure started 50 years ago of a computational chemist who was interested in molecules; what are they, what are their shape and how do they react. The story describes results, still valid today, obtained with highly simplified models of chemical reality and elementary computational methods and the gain resulting from the use of better models and more elaborate computational methods. It was necessary to select examples. In this presentation, focus is on hydride and dihydrogen complexes as well as on nucleophiles. Nucleophiles were considered as free hydrides in gas phase at the start of the rosarium while the Grignard reaction is treated with ab initio molecular mechanisms at the end of it. [ABSTRACT FROM AUTHOR]

• Carbamate and urea derivatives as representative linker units of polyurethanes. • Mn(I) effective catalyst for hydrogenation of carbamate or carbamide derivatives. • The different hydrogenation steps follow diverse mechanisms. • In most cases the H-transfer from the metal to carbonyl c atom is the slowest step. • Computations confirm a major resistance of carbamide derivatives to be hydrogenated. A comprehensive computational study is reported here on the mechanism of the reaction through which a Mn(I) pincer catalyst is able to assist the hydrogenation process of carbamate and urea derivatives, chosen as representative linker units of polyurethanes. Four substrate models, carbamate and urea derivatives, have been examined in order to evaluate their influence on the hydrogenation mechanism of polyurethanes to generate useful alcohols and amines organic building blocks. The outcomes of the computational exploration highlight a different behavior of the catalyst in assisting hydrogenation of carbamate or carbamide derivatives in the different steps of the whole reaction mechanism. Indeed, for the first hydrogenation step, the viability of a ligand-assisted mechanism has been found only for carbamide derivatives and involves a reversible structural change of the pincer ligand that can partially detach from the metal to favor the coordination of the molecule to be processed. The carbamate derivatives, instead, go through the formation of an intermediate in which the substrate interacts with the complex without binding. The mechanism of second hydrogenation is common to all the examined cases and requires the exploitation of the hemilabile nature of the PNN ligand. From the calculated energies put into play it clearly appears the great ability of the Mn(I) complex in catalyzing the hydrogenation of both carbamate and carbamide derivatives. [Display omitted] [ABSTRACT FROM AUTHOR]

Thiol dioxygenases are important enzymes for human health; they are involved in the detoxification and catabolism of toxic thiol‐containing natural products such as cysteine. As such, these enzymes have relevance to the development of Alzheimer's and Parkinson's diseases in the brain. Recent crystal structure coordinates of cysteine and 3‐mercaptopropionate dioxygenase (CDO and MDO) showed major differences in the second‐coordination spheres of the two enzymes. To understand the difference in activity between these two analogous enzymes, we created large, active‐site cluster models. We show that CDO and MDO have different iron(III)‐superoxo‐bound structures due to differences in ligand coordination. Furthermore, our studies show that the differences in the second‐coordination sphere and particularly the position of a positively charged Arg residue results in changes in substrate positioning, mobility and enzymatic turnover. Furthermore, the substrate scope of MDO is explored with cysteinate and 2‐mercaptosuccinic acid and their reactivity is predicted. [ABSTRACT FROM AUTHOR]

Reaction monitoring by electrospray ionization mass spectrometry (ESI‐MS) is a popular method for investigation of reaction mechanisms. Here, we present a new approach based on a coupling between a modular capillary flow reactor and ESI‐MS. The flow reactor allows a sequential adding of the reactants. We demonstrate the approach for oxidation of Ph2S by ArIO catalyzed by [(TPA)Fe(TfO)2] (ArIO=2‐(tBuSO2)C6H4IO, TPA=tris(2‐pyridylmethyl)amine, TfO−=triflate). In steps, we could follow the formation of the reactive iron(IV)oxo complexes, then the oxygen transfer reaction from the iron(IV)oxo to the sulfide, and finally the reoxidation of the iron complexes. The flow reactor also allows kinetic experiments by changing relative concentrations of the reactants. We could analyze in detail the formation of various [(TPA)FeIVO(X)]2+/+ complexes (X=MeCN, ArI, ArIO, TfO−) and compare their relative reactivity with Ph2S. The [(TPA)FeIVO(MeCN)]2+ complex is the most reactive complex for the oxygen atom transfer reaction whilst [(TPA)FeIVO(ArIO)]2+ prevails in solution under catalytic conditions. [ABSTRACT FROM AUTHOR]

The quantum calculation gives the insight of reaction mechanism in chemistry. In this work, we predict hydrogen evolution reaction (HER) mechanism in Ni(abt)2 (abt = 2‐aminobenzenethiolate) catalyst. Using density functional theory (DFT) and coupled‐cluster singles, doubles and perturbative triples (CCSD(T)) methods, we demonstrate the potential energy surface (PES) for the HER reaction result with two intermediate states (IM) and transition states (TS). Our result shows that the hydrogen atoms are migrated to Ni atom one by one from each of two amino groups. It indicates that the HER reaction in Ni(abt)2 occurs following the ligand‐assisted metal‐centered H2 production. Finally, two hydrogen atoms are merged in Ni atom site which generates hydrogen molecule. This would be meaningful prediction to understand the role of metal catalyst in HER reaction pathway. [ABSTRACT FROM AUTHOR]

The cytochrome P450 enzymes are important enzymes in the liver that trigger drug metabolism reactions. In biotechnology and biomimetic chemistry, synthetic models of the active species of P450 have been developed and designed and often react differently. Here, we investigate a biomimetic P450 model complex with phthalocyanine equatorial ligand rather than heme or porphyrin and with and without four tert-butyl substituents to the periphery of the ligand. Density functional theory studies on the electronic properties of the active species of the system, namely the iron(IV)-oxo with equatorial ligand cation radical species and its reactivity in oxygen atom transfer were studied. The work shows that a phthalocyanine equatorial ligand rather than porphyrin leads to a dramatic effect on the orbital energy levels of the iron(IV)-oxo species and creates a species with close-lying doublet and quartet spin states with two unpaired electrons in π*xz and π*yz for the Fe−O interaction coupled to a ligand radical in an a1u-type orbital. The latter contrasts P450 Compound I that has the a1u orbital doubly occupied and a singly occupied a2u orbital instead, As a consequence, our biomimetic model gives a reduced redox potential as compared to a system with a porphyrin-based radical and makes it a weaker oxidant. Nevertheless, the iron(IV)-oxo cation radical species with phthalocyanine ligand is shown to react with para-X-substituted thioanisole (X = CH3, Cl, CN, H, NO2, OCH3) substrates with small oxygen atom transfer barriers that align with the σ-Hammett parameter. The reactions are concerted with a single barrier leading to sulfoxide products. Synopsis: A series of density functional theory studies are presented on the electronic properties of a phthalocyanine ligated iron(IV)-oxo cation radical species and its reactivity with para-substituted thioanisole substrates. The studies show that despite the fact the reactant is electronically different from cytochrome P450 Compound I, it should react with sulfides in a concerted synchronous manner efficiently. [ABSTRACT FROM AUTHOR]

• The catalytic rules of the non-halogen anion and cation for the cycloaddition reaction were revealed. • the reaction mechanism was deeply explored by DFT calculations and in-situ IR spectroscopy. • Six new non-halogen ionic liquids were synthesized and used as efficient catalysts for cycloaddition reaction. Non-halogen ionic liquids are considered efficient catalyst for CO 2 conversion into cyclic carbonates. In this work, six carboxylic acid ionic liquids with different types and sizes of cations are designed and synthesized to systematically investigate the catalytic contribution of the non-halogen cation and anion for CO 2 conversion into cyclic carbonate. The result shows that the anion could improve the catalytic activity by improve the basicity of ionic liquids, and the cation that has a weak interaction with anion is more conducive for the reactivity. Further, the reaction mechanism is deeply studied by using the optimized [P 4444 ][IsoNic]: two reaction intermediates are captured by In-situ infrared, combined with DFT calculation, the anion directly inducing ring-opening mechanism is proposed. This work provides an in-depth understanding of catalytic contribution of non-halogen ionic liquids used in cycloaddition reaction. Graphical Abstract [Display omitted] [ABSTRACT FROM AUTHOR]

CFD simulations are presented for an in-depth study on different formulations (including implementation details) of the Eddy Dissipation Concept (EDC) turbulent combustion model, with infinitely fast chemistry as well as finite-rate chemistry with different reaction mechanisms. A turbulent line burner and a gaseous pool fire are chosen as first step in an extensive validation campaign for large eddy simulations of this kind, performed with OpenFOAM v1912. Artificial flame anchoring is necessary to establish a burning flame with finite-rate chemistry. Differences in mean temperatures, and the resulting flow fields, as obtained with the different formulations of the EDC combustion model, are explained by the impact of the reaction rates. CO is discussed as the most important of minor species as well. It is demonstrated that both the formulation of EDC and the choice of the chemistry mechanism can have a significant impact when the CFD mesh is not sufficiently fine, even though the flames studied are unsuppressed. This can lead to significant deviations from experimental data. This is a point of attention for future work, focusing on extinction and re-ignition phenomena. • CFD simulations with EDC and infinitely fast/finite-rate chemistry are presented. • The EDC formulation can significantly affect the mean flame temperatures. • The finite-rate chemistry reaction mechanism affects the local reaction rates. • Flame anchoring is needed to obtain a sustained flame with finite-rate chemistry. [ABSTRACT FROM AUTHOR]

This article, titled "Mechanism of CO2 Reduction to Methanol with H2 on an Iron(II)-scorpionate Catalyst," explores the reaction mechanism of a homogeneous catalyst that binds H2 and CO2 on an iron(II)-scorpionate complex. Through calculations, it is determined that the iron complex can cleave H2 into a hydride and proton, which then bind to different sites on the complex. CO2 is subsequently reduced through a series of hydride and proton transfer steps, ultimately resulting in the formation of methanol products. The full research article provides more detailed information on this topic. [Extracted from the article]

Reduced sulfur derived from thermochemical sulfate reduction (TSR) in Pb-Zn deposits is one of the long-debated issues in economic geology. The formation of - 2 valent sulfur (S2-) in Pb-Zn deposits associated spatially with basalts, may be related to the thermal reduction of SO 4 2- by ferrous ions (Fe2+). In the present study, hydrothermal experiments on the reduction of magnesium sulfate (MgSO 4) by ferrous carbonate (FeCO 3) were carried out to investigate the thermodynamics feasibility, kinetic characteristics and reaction mechanisms for the inorganic reduction of sulfates. The results show that the reduction of MgSO 4 by FeCO 3 is thermodynamically stronger than TSR of oil, gaseous hydrocarbons and solid bitumen. Moreover, this reduction reaction occurs at threshold temperatures below 300 °C under hydrothermal conditions, yielding the main products of magnetite (Fe 3 O 4), pyrite (FeS 2) and pyrrhotite (Fe 7 S 8). The reaction mechanism for the studied multiphase system at 400 − 525 °C involves at least nine elementary steps. The chemical kinetics for the FeCO 3 −MgSO 4 − H 2 O system is in accordance with the phase boundary control reaction model with apparent activation energy of 70 kJ/mol. The formation of S2- in carbonate-hosted Pb-Zn deposits associated spatially with basalts is most likely a two-stage sulfate reduction process involving Fe2+ (90 −140 °C) and organic matters (>140 °C) in series. The new findings from the inorganic reduction of sulfates would contribute to clarification of the genesis of Pb-Zn deposits and help to reconceptualize some of the long-standing controversial issues in this field. [Display omitted] • Reduction of MgSO 4 by FeCO 3 is much faster than TSR of hydrocarbons at 100–220 °C. • Sulfate reduction by FeCO 3 reaches 100% on a reasonable mineralization time scale. • Reaction mechanism for the FeCO 3 –MgSO 4 –H 2 O system involves nine elementary steps. • Reduction of MgSO 4 by FeCO 3 conforms to the phase boundary control model. • Formation of S2- in the studied Pb-Zn deposits is a two-stage sulfate reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new integrative design and synthesis to heterogeneous catalysts is studied. • The Al@Al 2 O 3 core–shell composite architecture is hydrothermally constructed. • Shape and crystal facets of γ-Al 2 O 3 crystallites are tailored by specific charge interactions. • Catalytic properties of Al@Al 2 O 3 core–shell are investigated for ethanol dehydration reaction. • The catalysts show significant surface characteristics with heat and mass transport properties. A novel integrated approach to designing and synthesizing heterogeneous catalysts with customized surface characteristics and improved heat and mass transport properties is studied. This unique approach utilizes hydrothermal reactions of aluminum (Al) metal substrates with controlled interfacial chemistry, manipulating the kinetics of aluminum hydroxide crystal growth to develop Al@Al 2 O 3 core–shell metal-ceramic composite micro-architectures. The shapes, spatial orientation, and surface-exposed crystal facets of the porous γ-Al 2 O 3 crystallites of the Al@Al 2 O 3 core–shell are effectively tailored via modulation of the specific charge interaction of the boehmite crystallites with heteroatom ions in the solution. The reaction chemistry and formation mechanism of the Al@Al 2 O 3 core–shell micro-composites with morphologically modulated γ-Al 2 O 3 crystallites are studied in detail, along with their physicochemical and catalytic properties. For the acid-catalyzed ethanol dehydration reaction, the Al@Al 2 O 3 catalysts with tailored morphologies and exposed γ-Al 2 O 3 crystal facets demonstrate the high effectiveness of the integrated design and synthesis approach to heterogeneous catalysts, modulating the intrinsic catalytic activities with enhanced mass and heat transport properties at the same time. [ABSTRACT FROM AUTHOR]

Two-dimensional simulations were carried out to investigate the flame acceleration and deflagration-to-detonation transition (DDT) in a combustion chamber filled with a subsonic or supersonic mixture by employing Navier-Stokes equations together with a detailed chemistry reaction mechanism of 11 species and 27 steps under adaptive mesh refinement. The effects of the initial mixture Mach number and mesh resolution on the flame acceleration and DDT were studied in detail, and the entire processes of the flame acceleration, DDT and detonation propagation were revealed. Two DDT mechanisms are obtained in a chamber having the same low blockage ratio but with different initial velocities of the mixture. Regime I: multiple shock wave collisions, shock focusing and shock reflection result in a rapid energy deposition in a small region; a direct detonation subsequently occurs in the boundary wall for the subsonic mixture. Regime II: the classic hot-spot mechanism due to the reactive gradient mechanism is responsible for the detonation transition in the supersonic mixture when the intense leading shock wave impacts and reflects on the solid surface. By increasing the initial mixture Mach number, the run-up time and distance to DDT are dramatically reduced. The flame front structure and propagation in the supersonic flow demonstrate that the detonation cell size rapidly increases when propagating into the smooth region due to detonation attenuation and resulting pressure decrease. Additionally, a much higher combustion temperature occurs in the upper and lower walls because of the Mach stem. In comparison, the results show that the detonation overdrive degree and pressure gain ratio in the subsonic mixture are higher than in the supersonic mixture. Moreover, flame propagation upstream also suggests that increased pressure and temperature occur in the inlet isolation section, even forming a localized explosion point. [ABSTRACT FROM AUTHOR]

• Free NH 2 OH could react with HMF to produce HMCF with a yield of 41% without catalyst. • ZnCl 2 was the suitable catalyst and could improve the yield of HMCF to 64%. • Hydroxylamine zinc chloride salt (ZnCl 2 ·2NH 2 OH) was prepared, which has the multiple roles of hydroxylamine stabilization, catalysis and nitrogen source in synthesis of HMCF with a 100% yield. • The solvent acetonitrile was involved in the mechanism of HMCF synthesis. Efficient and safe conversion of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarbonitrile (HMFC) with hydroxylamine zinc chloride salt (ZnCl 2 ·2NH 2 OH) obtained from a novel method was developed. Without a catalyst, free NH 2 OH could react with HMF to produce HMFC with a yield of 41% at 55 °C. ZnCl 2 was an appropriate catalyst that increased HMFC yield to 64%. However, the reaction has a potential explosion safety hazard and a low effective utilization rate of NH 2 OH due to the easy decomposition property of free NH 2 OH. To address these issues, ZnCl 2 ·2NH 2 OH was prepared to serve as a hydroxylamine stabilizer, catalyst, and nitrogen source in the synthesis of HMFC. Therefore, NH 2 OH could be slowly released to participate in the reaction, slowing the invalid decomposition and increasing the utilization rate of elemental N. Under optimal conditions of n(HMF): n(NH 2 OH) = 1:1.5, 100 °C for 20 min with acetonitrile as solvent, the yield of HMFC was 100%. A plausible reaction mechanism for HMFC synthesis was also proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

• Endogenous halide and/or base anions present in active Pd complexes. • Pd complexes activating aryl halide are anionic and contain halide anions. • Base- and/or hydroxo-containing Pd complexes activate arylboronic acid. Despite extensive studies regarding Pd intermediates reacting in the transmetalation step of the Suzuki–Miyaura reaction (SMR), direct evidence obtained under real turnover conditions supporting the widely accepted assumptions regarding the activity of Pd hydroxo complexes is lacking. Herein, results concerning the major reactivity of Pd-OH- and/or Pd-OR-containing complexes (RO− is the base anion) in the transmetalation step with arylboronic acid under "ligand-free" turnover conditions are presented. By contrast, aryl chloride activation was mainly realized through halide-containing Pd complexes. Data regarding the catalytic involvement of particular Pd species were obtained under real catalytic conditions by measuring differential selectivity of the competing reactions. In the reaction with demanding aryl chlorides catalyzed by "ligand-free" catalytic systems that is optimal from the viewpoints of environment, cost, and availability, the composition of active Pd complexes in the transmetalation step was similar to that for the reaction using more reactive aryl bromides and iodides. [Display omitted] [ABSTRACT FROM AUTHOR]

Bioorthogonal chemistry, click chemistry, in vivo, metabolic glycoengineering Keywords: bioorthogonal chemistry; click chemistry; in vivo; metabolic glycoengineering EN bioorthogonal chemistry click chemistry in vivo metabolic glycoengineering 1 1 1 04/10/23 20230406 NES 230406 Bioorthogonal reactions are biocompatible reactions that enable the study of biomolecules in living organisms. [Extracted from the article]

In their Review (DOI: 10.1002/chem.202203942), M. M. A. Mitry, F. Greco and H. M. I. Osborn critically appraise the suitability of bioorthogonal reactions for in vivo applications. Keywords: bioorthogonal chemistry; click chemistry; in vivo; metabolic glycoengineering EN bioorthogonal chemistry click chemistry in vivo metabolic glycoengineering 1 1 1 04/10/23 20230406 NES 230406 B Bioorthogonal chemistry b refers to reactions that can proceed in biological systems without interfering with biological processes. [Extracted from the article]

• DFT calculations revealed the reaction mechanism of oxidation of cumene by [Bmim]OH. • [Bmim]OH carbene-water has an activating effect on the O O bond of cumyl hydroperoxide (CHP), which greatly accelerates the rate-determining step of the cumene oxidation. • The cumylhydroxy radicals and carbene-OH radical-like intermediates resulting from homolytic cleavage reaction of CHP by [Bmim]OH can react with cumene via hydrogen abstraction. • The relationship between the catalytic activity and the properties of the active center was investigated. Experiment indicates that [Bmim]OH can effectively accelerate the oxidation reaction rate of cumene and improve the conversion of cumene. To investigate the catalytic effect of [Bmim]OH, the mechanism of molecular oxygen-activated [Bmim]OH-catalyzed oxidation reaction of cumene was proposed using the dispersion-corrected DFT-D3 calculation method. The nature of the catalytic effect of [Bmim]OH ionic liquid and the catalytic active site were investigated. The [Bmim]OH carbine-water structure plays an obvious catalytic role in the oxidation of cumene, which can induce the O O homolytic cleavage in cumyl hydroperoxide (CHP), leading to the formation of cumylhydroxy radicals (RO•) and carbene-OH radical-like intermediates, both of which are beneficial to the reactant with H of benzylic C H bond to accelerate the formation of cumyl radicals, involving in the propagation reaction that resulting in the formation of hydroperoxide and increasing the conversion of cumene. The overall reaction rate control step is the O O activation of CHP by [Bmim]OH carbine-water structure, which needs to overcome the energy barrier of 20.2 kcal/mol, lower than the auto-decomposition reaction energy barrier of CHP. The present results provide some new insights and understanding for the mechanism of the cumene oxidation catalyzed by ionic liquids. [Display omitted] [ABSTRACT FROM AUTHOR]

◆ Pd@s-CN catalysts were applied in carbonylation reaction with excellent performance. ◆ s-CN was used as a carrier for palladium and a ligand in carbonylation reaction. ◆ Visible light as a driving force successfully promotes carbonylation reactions. ◆ Spherical-like structure accelerated electron transport and provided more active sites. Exploring sustainable catalysts for the transition-metal-catalyzed carbonylation and acknowledging the corresponding interior mechanism are of great interest. Herein, palladium supported spherical-like graphitic carbon nitride catalyst (Pd@s-CN) was prepared through a microwave-assisted approach, where s-CN with larger surface area was synthesized via an exfoliation and refluxing method. The spherical-like structure of s-CN can offer abundant space preventing the agglomeration of Pd and creating more active sites for carbonylation reaction. Notably, with iodobenzene as the substrate, Pd@s-CN achieved 92% yield of benzoic acid, and its performance was better than that of PdCl 2 and Pd/C catalysts. The effects of thermal, light source and catalyst structure were investigated. Ultimately, the reaction mechanism of photocatalytic carbonylation was proposed. This environmentally friendly photocatalytic carbonylation method is expected to provide a new idea for carbonylation and other related organic synthesis reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Methyl 2-hydroxyisobutyrate was produced via self-catalyzed esterification. • Molecular 2-hydroxyisobutyric acid efficiently catalyzed its own esterification. • Methanol successfully served as both a reactant and solvent. • A kinetic model and a reaction mechanism were proposed. In this paper, we first propose a method to produce methyl 2-hydroxyisobutyrate (HBM), which is an essential chemical in semiconductor manufacturing processes, through esterification of 2-hydroxyisobutyric acid (HBA) with methanol without adding any catalyst or solvent. We found that molecular HBA efficiently catalyzed its own esterification, and methanol successfully served as both a reactant and solvent. Significant HBA conversion (ca. 87%) with no byproducts was achieved via self-catalyzed esterification at a reaction temperature of 120 °C and reaction time of 48 h. In comparative experiments using Amberlyst-15 and Nafion NR50 catalysts, ca. 80% and ca. 93% of HBA conversion were obtained at 90 °C for 6 h, respectively. A kinetic study of the self-catalyzed esterification demonstrated that the reaction order relative to HBA was two, and the activation energy was 44.1 kJ mol−1. Based on the kinetics, we suggest a possible reaction mechanism, where the molecular HBA catalyzes the reaction (rather than the protons generated by dissociation of HBA). Thus, self-catalyzed esterification of HBA with methanol could be a promising method to produce HBM. [Display omitted] [ABSTRACT FROM AUTHOR]

Keywords: Antiscalants; Crystal Engineering; Green Chemistry; Reaction Mechanisms; Solid-State REDOR NMR EN Antiscalants Crystal Engineering Green Chemistry Reaction Mechanisms Solid-State REDOR NMR 1 1 1 09/28/22 20221004 NES 221004 B Amorphous calcium carbonate b (ACC) is a pivotal precursor in biomineralization, central to geological and industrial calcification. In their Research Article (e202208475), Asher Schmidt, Dirk Zahn, Stephan E. Wolf et al. decode the underlying molecular mechanisms that regulate both prenucleation cluster and solution composition and proceed outside the established conceptional framework. In their Research Article (e202208475), Asher Schmidt, Dirk Zahn, Stephan E. Wolf et al. decode the underlying molecular mechanisms that regulate both prenucleation cluster and solution composition and proceed outside the established conceptional framework. [Extracted from the article]

Keywords: Antiscalants; Crystal Engineering; Green Chemistry; Reaction Mechanisms; Solid-State REDOR NMR EN Antiscalants Crystal Engineering Green Chemistry Reaction Mechanisms Solid-State REDOR NMR 1 1 1 09/28/22 20221004 NES 221004 B Amorphes Kalziumcarbonat b (ACC) ist ein wichtiger Vorläufer in der Biomineralisierung und von zentraler Bedeutung für die geologische und industrielle Kalzifizierung. Einige kleine organische Moleküle haben die Fähigkeit, die Bildung, Zusammensetzung und Stabilität von ACC stark zu beeinflussen. In ihrem Forschungsartikel (e202208475) entschlüsseln Asher Schmidt, Dirk Zahn, Stephan E. Wolf et al. die zugrundeliegenden molekularen Mechanismen, die sowohl die Pränukleation als auch die Zusammensetzung der Lösung regulieren. [Extracted from the article]

• Monatomic transition metal M supported MoS 2 (M/MoS 2 , M=Co, Ni, Cu) was constructed. • Structural properties, molecular adsorption and the reaction mechanism for WGSR were investigated. • Doping transition metal can increase the charge transfer and reduce the band gap of M/MoS 2. • Potential WGSR mechanism is association mechanism, in which HCOO* intermediate plays leading role. • Supporting metal can effectively reduce the reaction energy barrier of WGS. In this paper, a two-dimensional M/MoS 2 material system was constructed by supporting transition metal atoms M (M=Co, Ni, Cu) on the surface of MoS 2. The structural properties, molecular adsorption and the reaction mechanism for water gas shift reaction (WGSR) were investigated based on DFT calculation. Compared with pristine MoS 2 , doping transition metal can make M/MoS 2 more stable because the charge transfer between metal and MoS 2 increases the polarization of Mo and S. The adsorption performance is significantly improved, which is conducive to the forward progress of the reaction. The band gap of materials is narrowed, which motivates MoS 2 transforms to metal phase. The supporting metal can increase the charge transfer and the number of active sites in the system, which can effectively reduce the reaction energy barrier of WGS and improve the catalytic activity. The most potential WGSR mechanism of the three materials is the association mechanism, in which the HCOO* intermediate plays the leading role. [Display omitted] [ABSTRACT FROM AUTHOR]

• The M-doped CePO4 catalysts were prepared by the coprecipitation method. • The incorporation of M improved the NH 3 -SCR activity on the CePO 4. • The reaction mechanism followed the Eley-Rideal and Langmuir-Hinshelwood mechanism. A series of Metals doped M-CePO 4 (M =Zr, Co, Mo, Cu) catalysts were prepared via the coprecipitation method for selective catalytic reduction of NO with NH 3 (NH 3 -SCR). The results showed that the NO x conversion of M-CePO 4 were higher than that of CePO 4 , especially the Mo-CePO 4 catalysts exhibited the best low-temperature activity and N 2 selectivity, the Mo-CePO 4 catalysts can reach about 99% at 300 °C and excellent 70 h long stability with the coexistence of SO 2 and H 2 O. The effect of metal elements doping on physiochemical properties of catalysts were characterized by XRD, BET, Raman, TEM, XPS, H 2 -TPR and NH 3 -TPD. SEM and TEM analysis. The results showed that part of M ions doped into CePO4 lattice resulted in lattice shrinkage. More importantly, the MO x species could not only increased the relative content of Ce3+ and surface adsorption oxygen (O′) of M-CePO 4 catalysts, but also increased the specific surface area of the catalysts. It could provide more reaction sites for active gas to promote the activation of NH 3 and enhance oxidation–reduction performance. The in-situ DRIFTS results suggested that NH 3 were adsorbed on both Lewis and Bronsted acid sites which can easily react with NO x gas. The NO species were adsorbed on Mo-CePO 4 in the form of bidentate nitrate. The main reactants of Mo-CePO 4 catalysts were NH 3 linked to Lewis acid sites and bidentate nitrate species on the catalytic surface. The Eley–Rideal and Langmuir–Hinshelwood mechanisms coexisted in the SCR reaction route. According to the characterization results of the catalysts, the mechanism of Mo promoting the activity of NH 3 -SCR at low temperature was proposed (Fig. 13.). NH 3 binds to Lewis acid centers, and NH4+ adsorbs on Brønsted acid centers, monotone nitrates and bidentate nitrates. Studies had shown that NH 2 is an important medium in the reaction of NO (gas phase) to produce NH 2 NO and then decompose into N 2 and H 2 O. As shown in Fig. 12(a), the reaction of NH 3 -SCR on the catalyst follows the Eley-Rideal (E-R) mechanism. The NH 3 Lewis acid sites and NH4+ acid sites adsorbed on Brønsted react with NO (gas phase). As shown in Fig. 12(b), monodentate and bidentate nitrates reacted with adsorbed NH 3 species, following the Langmuir-Hinshelwood (L-H) mechanism [51]. The Mo6+/Mo5+ and Ce4+/Ce3+ redox cycles on the catalyst surface participate in the whole process of the catalytic reaction. At this stage, the electron transfer process promoted the conversion of oxygen vacancy and unsaturated chemical bond, thus enhancing the adsorption activation capacity of NO and NH 3 , promoting the decomposition of NO molecule, and improving the catalytic performance. The –NH 2 s species were intermediate adsorbed and reacted with the activated nitrate, eventually becoming N 2. In the process of NO reduction, NH 3 showed selectivity to the reaction intermediates, preferentially reacted with monotone nitrate and bidentate nitrate. [Display omitted] [ABSTRACT FROM AUTHOR]