Achieving asymmetric redox chemistry for oxygen evolution reaction through strong metal-support interactions

Water electrolysis poses a significant challenge for balancing catalytic activity and stability of oxygen evolution reaction(OER)electrocatalysts.In this study,we address this challenge by constructing asymmetric redox chemistry through elaborate surface OO–Ru–OH and bulk Ru–O–Ni/Fe coordination moieties within single-atom Ru-decorated defective NiFe LDH nanosheets(Ru@d-NiFe LDH)in conjunction with strong metal-support interactions(SMSI).Rigorous spectroscopic characterization and theoretical calculations indicate that single-atom Ru can delocalize the O 2p electrons on the surface and optimize d-electron configurations of metal atoms in bulk through SMSI.The^(18)O isotope labeling experiment based on operando differential electrochemical mass spectrometry(DEMS),chemical probe experiments,and theoretical calculations confirm the encouraged surface lattice oxygen,stabilized bulk lattice oxygen,and enhanced adsorption of oxygen-containing intermediates for bulk metals in Ru@d-NiFe LDH,leading to asymmetric redox chemistry for OER.The Ru@d-NiFe LDH electrocatalyst exhibits exceptional performance with an overpotential of 230 mV to achieve 10 mA cm^(−2)and maintains high robustness under industrial current density.This approach for achieving asymmetric redox chemistry through SMSI presents a new avenue for developing high-performance electrocatalysts and instills confidence in its industrial applicability.

Reaction Activity of Kao linite Surfaces:Quantum Chemistry Calculations

The anion kaolinite surface interactions and AuS - adsorption onto the surfaces of kaolinite were studied using the self consistent field discrete variation (SCF-X α-DV) method.Electronic structure and energies of the system of anion AuS - adsorbed on an atomic cluster of kaolinite were calculated.The results show that the systems with lower total energy are those AuS - adsorbed on the edge surfaces,which indicates that the systems of adsorption of AuS - on the edges are more stable relative to those adsorbed on the basal plane.On the other hand,bond order data suggest that significant shifting of atomic charge and the overlapping of electronic cloud between Au (Ⅰ) of the AuS - and the surface ions of kaolinite would take place in the systems with AuS - being adsorbed on the edges,especially at the site near Al octahedra.Therefore,it can be concluded that edge sites will dominate the complexation reactions of the surfaces of kaolinite,with negligible contributions from other functional groups on the basal plane,which are dominated by either siloxane sites in silica layers or aluminol sites in gibbsite layers.

CHEMISTRY OF DENUDATINE I. THE REACTIONS OF DENUDATINE AND DIACETYLDENUDATINE WITH NBS-HOAc

The reactions of denudatine 1 and diacetyldenudatine 2 with NBS-50% HOAc soln. afforded 4 and 6, respectively, in high yields.Treatment of 6 with (Ac)_2CO-Pyr. gives 7. The structures of 3,6 and 7 were deduced on the basis of spectral and chemical methods.

α-OXOKETENE CYCLIC DITHIOACETAL CHEMISTRY(XⅢ)-THE ETHERIFYING REACTION ON THE ADDUCTS OF ALIPHATIC α-OXO KETENE CYCLIC DITHIOACETALS WITH ALLYL MAGNESIUM BROMIDE

Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.

α-Oxoketene Cyclic S,S-Acetals Chemistry──Reaction of α,α′-Dioxo (ester)ketene Cyclic S,S-Acetals with Ethylenediamine

α, α′ -Dioxo (ester ) ketene cyclic S, S-acetais 2 were reacted withethyleneddriine to chrd α, α′-dioxo (ester)ketene cyclic N, N-acetals 3 Thisprocess provides a new method for the synthesis of 3 in gnd yteld under mildcondition. All products are confirmed with elementai analpeis, IR, 1H NMR and13~C NMR

反应树(Reaction Tree)--归纳总结法在“药物合成反应”教学中的应用

针对“药物合成反应”这一课程有机反应多、化合物结构复杂的特点,设计用一种“反应树”式的归纳总结方法对教材每个章节的有机反应进行总结。反应树可以清晰地展示同一章节里不同有机反应之间的区别与联系,使看上去无规律的有机反应更加系统化、条理化,从而帮助提高教学效果。

Tunable vacancy defect chemistry on free-standing carbon cathode for lithium-sulfur batteries

The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li-S redox reactions.Such rationally regulated defect engineering realizes the synchronization of ion/electron-conductive and defect-rich networks on the threedimension carbon cathode,leading to its tunable activity for both relieving the shuttle phenomenon and accelerating the sulfur redox reaction kinetics.As expected,the defective carbon cathode harvests a high rate capacity of 1217.8 mAh g^(-1)at 0.2 C and a superior capacity retention of61.7%at 2 C after 500 cycles.Even under the sulfur mass loading of 11.1 mg cm^(-2),the defective cathode still holds a remarkable areal capacity of 8.5 mAh cm^(-2).

Multi-electron reaction concept for the universal battery design

Electrochemical batteries define the contraption stores electricity in the direct form of chemical energy with high efficiency. If the energy conversion process can be reversed, namely the input and output of electricity both being permitted, the batteries are termed rechargeable batteries or also secondary batteries accordingly [1]. These decades have witnessed the rapid development of batteries because of the demands for transportation of information and mass in the mobile area, and stationary storage for the implementation of renewable energy technologies.

Modern applications of scanning electrochemical microscopy in the analysis of electrocatalytic surface reactions

Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy,such as those involved in water splitting and artificial photosynthesis,owing to its energy efficiency,simple fabrication,and ease of operation.In this view,it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest,and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations.In this review,we introduce several key methods of scanning electrochemical microscopy(SECM)in its applications towards electrocatalysis.A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism.New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced,and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.

Mechanism and Kinetic of Free Radical Reactions for Propane Using theoretical Calculations

Quantum calculation method has been used to understand and investigate the free radical reactions of propane with hydroxyl radical in vacuum through modem quantum mechanics that is package on hyperchem 8.02 program. Optimized structures and structural reactivates have been studied through bond stability and angles using DFT calculation based on the basis set 6-31G＊. Energetic properties have been calculated like total energy, Gibbs free energy, entropy, heat of formation, and rate constant for all chemical species that＇s participate in the suggested reaction mechanism. Reaction mechanism and rate determining step had been suggested according to calculation of energy barrier values, and compares between the suggested competitive reactions for each probable reaction step. Suggested structures and the probable transition states have been studied.

No-solvent Condensation Reaction of Amino Acids and their Derivatives with Pyrandione

Synthesis of a novel series of N-pyrandione substituted amino acids and their esters 3 via a condensation reaction between pyrandione and amino acid or their derivatives in excess ethyl orthoformate without solvent is described. The stereochemistry of 3 has been discussed.

Multicomponent Reaction in Ionic Liquid: A Novel and Green Synthesis of 1, 4-Dihydropyridine Derivatives

An efficient and green method for the synthesis of 1, 4-dihydropyridine derivatives mediated in an ionic liquid, [bmim][BF4], through a four-component condensation process of aldehydes, 1, 3-dione, Meldrum＇s acid and ammonium acetate is disclosed in this paper.

Reaction of Bis(Methylcyclopentadienyl) Lanthanide Amido Complex with n-Hexyl isocyanate-Synthesis and Characterization of {(MeC_5H_4)_2YbOC(NPh_2)N(n-hexyl)}_2

Bis （methylcyclopentadienyl） lanthanide amido complex （MeCp） 2YbNPh2 （THF） reacted with n-hexyl isocyanate （n-nexylNCO） in 1：1 molar ratio to give {（MeC5H4）2Yb[OC（NPh2）N（n-hexyl）] }2（1）. Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533（11） nm, b =2.9533（11） nm, c = 1.5873（6） nm, V= 11.9896（80） nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1（Mo Kα）, F（000） =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.

Finkelstein Reaction in Functionalized Crown-ether Ionic Liquids

Functional crown-ether ionic liquids were used as catalytic green solvents of Finkelstein reaction of 1-bromooctane and iodide. The rate and yield of the reaction were obvious improved compared with that using crown ether in water. No free crown ether loss was observed after reaction.

Reduced chemistries with the Quantemol database (QDB)

Typical feed gas mixtures used in technological and other plasmas may give rise to reaction networks involving several hundred reactions.Such chemistries are often too large to be used in full reactor simulations and it is therefore desirable to construct reduced chemistry networks which mimic as closely as possible the behavior of the full chemistry but employ far fewer individual reactions and species.Constructed chemistries are available from the Quantemol database (QDB) and two approaches to constructing reduced chemistry from these chemistries based on (a) physical intuition and (b) sensitivity analysis of dominant reaction pathways,are explored.In doing this it is necessary to consider different pressure and power regimes.Reduced chemistry sets are presented for CF4/O2/N2/H2,for which 396 reactions and 52 species are reduced to 71 reactions and 26 species,and for pure O2,for which 45 reactions and 10 species are reduced to 34 reactions.

A Theoretical Research on the Intermediate in the Reaction of N-Phosphorylamino-acid to form Peptide or Ribotide

In order to explain the high activity of N-phosphoryl-α-amino acids, ab initio and MNDO calculations are performed to study the reaction pathway of the intermediate formation from N-dimethylphosphoryl-α-alanine (DMP-α-Ala) and the structures and energies involved in the reaction.

Rapid and durable oxygen reduction reaction enabled by a perovskite oxide with self-cleaning surface

The growth of electrochemically inert segregation layers on the surface of solid oxide fuel cell cathodes has become a bottleneck restricting the development of perovskite-structured oxygen reduction catalysts.Here,we report a new discovery in which enriched Ba and Fe ions on the near-surface of Nd_(1/2)Ba_(1/2)Co_(1/3)Fe_(1/3)Mn_(1/3)O_(3-δ)spontaneously agglomerate into dispersed Ba_(5)Fe_(2)O_(8) nanoparticles and maintain a highly active and durable perovskite structure on the surface.This unique surface selfcleaning phenomenon is related to the low average potential energy of Ba_(5)Fe_(2)O_(8),which is grown on the near-surface layer.The electrochemically inert Ba_(5)Fe_(2)O_(8) segregation layer on the near-surface of the perovskite catalyst achieves self-cleaning by regulating the formation energy of enriched metal oxides.This self-cleaned perovskite surface exhibits an ultrafast oxygen exchange rate,high catalytic activity for the oxygen reduction reaction,and good adaptability to the actual working conditions of solid oxide fuel cell stacks.This study paves a new way for overcoming the stubborn problem of perovskite catalyst surface deactivation and enriches the scientific knowledge of surface catalysis.

Crossed Molecular Beams and Theoretical Studies of the O(~3P)+1,2-Butadiene Reaction:Dominant Formation of Propene+CO and Ethylidene+Ketene Molecular Channels

Detailed understanding of the mechanism of the combustion relevant multichannel reactions of O(3P) with unsaturated hydrocarbons (UHs) requires the identification of all primary reaction products, the determination of their branching ratios and assessment of intersystem crossing (ISC) between triplet and singlet potential energy surfaces (PESs). This can be best achieved combining crossed-molecular-beam (CMB) experiments with universal, soft ionization, mass-spectrometric detection and time-of-flight analysis to high-level ab initio electronic structure calculations of triplet/singlet PESs and RRKM/Master Equation computations of branching ratios (BRs) including ISC. This approach has been recently demonstrated to be successful for O(3P) reactions with the simplest UHs (alkynes, alkenes, dienes) containing two or three carbon atoms. Here, we extend the combined CMB/theoretical approach to the next member in the diene series containing four C atoms, namely 1,2-butadiene (methylallene) to explore how product distributions, branching ratios and ISC vary with increasing molecular complexity going from O(3P))+propadiene to O(3P)+1,2-butadiene. In particular, we focus on the most important, dominant molecular channels, those forming propene+CO (with branching ratio ∽0.5) and ethylidene+ketene (with branching ratio ∽0.15), that lead to chain termination, to be contrasted to radical forming channels (branching ratio ∽0.35) which lead to chain propagation in combustion systems.

Comparative Studies of New Complexes Synthesized by Chemical and Tribochemical Reactions Derived from Malonic Acid Dihydrazide (L;MAD) with Cu²⁺and Co²⁺Salts

The reaction of L (MAD) with Cu2+ and Co2+ chlorides affords new metal complexes. The isolated solid complexes were synthesized by two different techniques i.e., chemical and tribochemical methods. Four new complexes were synthesized by direct chemical reactions of MCl2 (M = Co2+ and Cu2+) with MAD in absolute EtOH. The isolated solid complexes were used as starting compounds to synthesize another four new complexes using tribochemical technique by grinding the previous complexes in the solid state with excess KI in agate mortar. The results of the isolated complexes indicate the substitution of the chloride by iodide ions during grinding and extraction of the complexes by a mixture of solvents (EtOH + MeOH). Also, the results suggest that no reduction of Cu2+ or oxidation of Co2+ complexes is observed. The IR spectra of the complexes suggest that L acts in a bidentate manner. Moreover, the results of electronic spectra and magnetic measurements for the chloride and iodide complexes suggest distorted-octahedral and/or tetrahedral for Cu2+ and high-spin octahedral and/or tetrahedral structures around the Co2+ ion, respectively.

Chemical kinetic studies on interfacial reaction in SCS-6 SiC/Ti matrix composites

Interfacial reaction and its mechanism of SiC/Ti composite were revealed by chemical kinetic studies. A two-step dynamic model of interfacial reaction in SCS-6 SiC/Ti composites was built up, and the rate constant and the activation energy of the interfacial reactions were obtained based on the quantum chemistry calculation. The results show that the first step, in which the atomic Ti, C and Si are decomposed from Ti matrix and SiC fiber, respectively, is a rate-determined step because the activation energy of the step is much larger than that of the second one in which deferent interfacial reaction products form. The theoretically predicted result of the interfacial reaction is coincident with that of experimental observation.