Bonds In Molecules Research Articles

Effect of the electronic properties of the side charges of neutral solvent molecules on the charges of the N and H atoms of the carbazole molecule: IR experiment and DFT calculations

The IR spectral parameters of the absorption band of the valence vibration of the NH bond of the carbazole molecule in several neutral solvents (n-hexane C6H14, carbon tetrachloride CCl4, chloroform CHCl3, benzene C6H6) have been measured. It has been experimentally established that the position of the maximum of the NH vibrational band of the carbazole molecule in solvents undergoes a low-frequency shift relative to the gas phase. This shift increases in the series C6H14, CCl4, CHCl3, C6H6. The change in the magnitude of the linear shift is well described by the Kirkwood-Bauer-Magat KBM ratio in C6H14, CCl4, CHCl3. The presence of a linear shift may indicate that only universal interactions take place. The deviation of this ratio of shift magnitude for carbazole in benzene is interpreted as a manifestation of intermolecular complexation. Quantum-chemical calculations of the position of the absorption band position of the valence vibration of the NH bond of the carbazole molecule in these solvents, carried out by the electron density functional method B3LYP/6-31G using the Gaussian 09W program package, also showed a low-frequency shift relative to the gas phase.It was found that for the carbazole molecule in the condensed phase relative to the gas phase the following effects of changing the magnitude of charges on atoms N13 and H14 take place: 1 – increase in the positive sign of the charge on both atoms; 2 – the change in charge magnitude is larger on the nitrogen atom than on the hydrogen atom for both solvents (whose molecules have a dipole moment ∼0: C6H14, CCl4); 3 – the chlorine containing environment has a greater effect on the charge change in the carbazole molecule than the proton containing environment (whose molecules have a dipole moment ∼0: C6H14, CCl4).The correlation between the change of charges on atoms N13 and H14 with the value of electronegativity ξ of the side solvent atoms was established.Thus, it is shown that the charges on the 13N and 14H atoms of the carbazole molecule undergo changes in the presence of universal interactions, and the magnitude of the charge change depends on the electronic properties of the side atoms of the nearest solvent molecules. A hypothesis is proposed to explain the different frequency shift of the NH vibrational frequency of the molecule for chlorine-containing and hydrogen-containing side atoms of neutral solvent molecules, which takes into account different values of ξ for nitrogen and hydrogen atoms.

Growth Kinetics of Graphene on Cu(111) Foils from Methane, Ethyne, Ethylene, and Ethane

AbstractChemical vapor deposition of carbon precursors on Cu‐based substrates at temperatures exceeding 1000 °C is currently a typical route for the scalable synthesis of large‐area high‐quality single‐layer graphene (SLG) films. Using molecules with higher activities than CH4 may afford lower growth temperatures that might yield fold‐ and wrinkle‐free graphene. The kinetics of growth of graphene using hydrocarbons other than CH4 are of interest to the scientific and industrial communities. We measured the growth rates of graphene islands on Cu(111) foils by using C2H2, C2H4, C2H6 and CH4, respectively (each mixed with H2). From such kinetics data we obtain the activation enthalpy (ΔH≠) of graphene growth as shown in parentheses (C2H2 (0.93±0.09 eV); C2H4 (2.05±0.19 eV); C2H6 (2.50±0.11 eV); CH4 (4.59±0.26 eV)); C2Hy (y=2, 4, 6) show similar growth behavior but CH4 is different. Computational fluid dynamics and density functional theory simulations suggest that C2Hy differs from CH4 due to different values of adsorption energy and the lifetime of relevant carbon precursors on the Cu(111) surface. Combining experimental and simulation results, we find that the rate determining step (RDS) is the dissociation of the first C−H bond of CH4 molecules in the gas phase, while the RDS using C2Hy is the first dehydrogenation of adsorbed C2Hy that happens with assistance of H atoms adsorbed on the Cu(111) surface. By using C2H2 as the carbon precursor, high‐quality single‐crystal adlayer‐free SLG films are achieved on Cu(111) foils at 900 °C.

Conformational Geometry Matters: The Case of the Low-Melting-Point Systems of Tetrabutylammonium Triflate with Fumaric or Maleic Acid

For this article, the interaction of tetrabutylammonium trifluoromethanesulfonate (TBATFO) with either fumaric (FUM) or maleic (MAL) acid has been investigated. These acids are isomers and can be considered the trans and cis configurations of the same molecular geometry. When TBATFO is mixed with FUM, an eutectic point is obtained for a relative composition of 90-10 (molar ratio), with a melting point of ≈90 °C. If maleic acid is mixed with TBATFO, one obtains an inhomogeneous phase with the retention of a solid portion immersed in a liquid phase, even above 90 °C. DFT calculations helped to model the interaction between the components. It is suggested herein that TBATFO interacts more strongly with FUM than with MAL, due to possible interactions in two different sites for hydrogen bonding (HB) in FUM. In MAL, one of the HB sites is instead retained in the intramolecular interactions; therefore, fewer sites are available for intermolecular interactions. Infrared spectroscopy measurements have confirmed this scenario, in which the hydrogen bonds of the acid molecules are replaced by HB between the acid and the ionic couple: for both kinds of mixtures, the vibration region of the OH bonds is strongly affected by mixing. However, in the case of FUM, the vibrations of the SO3 group of the TFO anion are displaced, while they remain in practically the same frequency position in the case of MAL.

Growth Kinetics of Graphene on Cu(111) Foils from Methane, Ethyne, Ethylene, and Ethane.

Chemical vapor deposition of carbon precursors on Cu-based substrates at temperatures exceeding 1000 °C is currently a typical route for the scalable synthesis of large-area high-quality single-layer graphene (SLG) films. Using molecules with higher activities than CH4 may afford lower growth temperatures that might yield fold- and wrinkle-free graphene. The kinetics of growth of graphene using hydrocarbons other than CH4 are of interest to the scientific and industrial communities. We measured the growth rates of graphene islands on Cu(111) foils by using C2H2, C2H4, C2H6 and CH4, respectively (each mixed with H2). From such kinetics data we obtain the activation enthalpy (ΔH≠) of graphene growth as shown in parentheses (C2H2 (0.93±0.09 eV); C2H4 (2.05±0.19 eV); C2H6 (2.50±0.11 eV); CH4 (4.59±0.26 eV)); C2Hy (y=2, 4, 6) show similar growth behavior but CH4 is different. Computational fluid dynamics and density functional theory simulations suggest that C2Hy differs from CH4 due to different values of adsorption energy and the lifetime of relevant carbon precursors on the Cu(111) surface. Combining experimental and simulation results, we find that the rate determining step (RDS) is the dissociation of the first C-H bond of CH4 molecules in the gas phase, while the RDS using C2Hy is the first dehydrogenation of adsorbed C2Hy that happens with assistance of H atoms adsorbed on the Cu(111) surface. By using C2H2 as the carbon precursor, high-quality single-crystal adlayer-free SLG films are achieved on Cu(111) foils at 900 °C.

Aliphatic Nitrile Template Enabled meta-C-H Olefination of Indene Enoate Esters under Microwave Accelerating Conditions.

Site-selective activation of a particular remote C-H bond in molecules with multiple C-H bonds remains challenging in organic synthesis. In addition, evolving such transformations via the utilization of unconventional techniques is highly desirable. We demonstrated hitherto unexplored double bond geometry-guided and end-on nitrile-template-assisted meta-C-H functionalization of indene enoate esters under microwave-accelerated conditions. Significantly, the strategy exhibited broad compatibility concerning the substrates and olefin coupling partners. Remarkably, drug diversification has also been showcased.

Concept of electrons pairing during the formation of covalent chemical bonds

This research studies the forces acting in an electron pair with antiparallel spins participating in forming a covalent chemical bond between atoms. The first is the force of electrostatic repulsion of electrons. The second is the gravitational attraction of these electrons. The third is the force of electromagnetic attraction between the electron pair. From calculations it follows, that the force of gravitational attraction is negligible, and therefore it is not able to withstand the force of electrostatic repulsion between electrons. However, the force of electromagnetic attraction between a pair of electrons with antiparallel spins turned out to be hundreds of times greater than the force of their electrostatic repulsion. As a result, the formation of stable electron pairs in molecular orbitals becomes possible. Thus, valence electrons of neighboring atoms interact with each other like femto-electromagnets, as a result of which a stable bond is formed between these electrons. Calculations have shown that in hydrogen molecule the force of electrostatic attraction between nuclei and paired electrons of a molecular orbital significantly exceeds the force of electrostatic repulsion of nuclei, which ensures the formation of a strong covalent chemical bond. To form covalent bonds in other molecules, the force of electrostatic attraction between the nuclei and paired electrons of the molecular orbitals must be much greater than the forces of electrostatic repulsion between both the positively charged nuclei and the negatively charged electrons of the atomic orbitals of different atoms.

A newly-constructed technology to remove and recover diethyl phthalate from wastewater by using the instant plasticization assembly ability of PVC

Diethyl phthalate (DEP) is a typical environmentally organic pollutant, widely used in the production process of polyvinyl chloride (PVC) to improve the flexibility of plastic materials. Its interaction with living organisms can inflict considerable harm to reproductive system functions. This research aims to utilize tetrahydrofuran (THF) to selectively break the chemical bonds in PVC molecules to provide more adsorption sites. Then incorporates the plasticizing assembly process of PVC to instantly remove and recover DEP from wastewater, achieving waste utilization, and sustainable environmental development. The research found that PTFR with a concentration of around 75 mg/L shows the best DEP removal efficiency. Sequencing batch processing removes more DEP compared to direct processing under the same material usage conditions. Furthermore, the recovery rate of DEP can reach over 90%. The technology demonstrates notable enhancements in removal efficiency and adsorption duration when compared to conventional adsorption techniques. This research has established an instant and efficient method for DEP removal, providing a new idea and technology for plasticizer treatment in practical wastewater.

Catalytic undirected methylation of unactivated C(sp3)-H bonds suitable for complex molecules.

In pharmaceutical discovery, the "magic methyl" effect describes a substantial improvement in the pharmacological properties of a drug candidate with the incorporation of methyl groups. Therefore, to expedite the synthesis of methylated drug analogs, late-stage, undirected methylations of C(sp3)-H bonds in complex molecules would be valuable. However, current methods for site-selective methylations are limited to activated C(sp3)-H bonds. Here we describe a site-selective, undirected methylation of unactivated C(sp3)-H bonds, enabled by photochemically activated peroxides and a nickel(II) complex whose turnover is enhanced by an ancillary ligand. The methodology displays compatibility with a wide range of functional groups and a high selectivity for tertiary C-H bonds, making it suitable for the late-stage methylation of complex organic compounds that contain multiple alkyl C-H bonds, such as terpene natural products, peptides, and active pharmaceutical ingredients. Overall, this method provides a synthetic tool to explore the "magic methyl" effect in drug discovery.

PH-Induced color changeable AIE-featured polymeric micelles for self-indicating anticancer drug delivery

Multifunctional polymeric micelles, which possess capabilities for tracking, bioimaging, stimuli-responsive drug release and tumor targeting, are essential in facilitating the effective delivery of anticancer drugs. Hence, a novel copolymer (CD-CS-Bio-TPAA, CCBT) was synthesized with biotin and hydroxypropyl-β-cyclodextrin conjugated chitosan as the hydrophilic segment and aggregation-induced emission (AIE) featured tetraphenylethene derivative (TPAA) as the hydrophobic segment. Interestingly, under acidic conditions, CCBT exhibited color-tunable AIE behavior as a result of the cleavage of benzoic imine bonds in TPAA molecules, transitioning from red to yellow. Furthermore, CCBT could also self-assemble into polymeric micelles and be used as drug carriers to encapsulate paclitaxel (PTX) (PTX/CCBT PMs) for self-indicating cancer therapy. In vitro release experiments demonstrated that PTX/CCBT PMs could release drugs specifically under acidic conditions. Fluorescence imaging experiments demonstrated that CCBT PMs exhibited excellent cell imaging capabilities and could be tracked due to their unique color-changing behavior. Moreover, PTX/CCBT PMs exhibited notable cytotoxic effects on MCF-7 cells and showed selective internalization by MCF-7 cells through biotin receptor-mediated active targeting. In vivo antitumor experiments confirmed that PTX/CCBT PMs possessed remarkable tumor-inhibiting effects and low systemic toxicity. This work suggested that PTX/CCBT PMs provided new ideas for self-indicating breast cancer treatment.

Main-group compounds selectively activate natural gas alkanes under room temperature and atmospheric pressure

Most C–H bond activations of natural gas alkanes rely on transition metal complexes. Activations by using main-group systems have been reported but required heating or photo-irradiation under high atmospheric pressure with rather low regioselectivity. Here we report that Lewis acid-carbene adducts facilely undergo oxidative additions to C–H bonds of ethane, propane and n-butane with high selectivity under room temperature and atmospheric pressure. The Lewis acids can be moved by the addition of a base and the carbene-derived products can be easily converted into aldehydes. This work offers a route for main-group element compounds to selectively functionalise C–H bonds of natural gas alkanes and other small molecules.

Utilization of papermaking black liquor as liquid phase for hydrothermal carbonization of corn stalks: The unique role of alkali for production of hydrochar

Papermaking black liquor (BL) contains a large amount of organic matter, alkali, and salt, which has high value in industrial and agricultural production. In the present paper, hydrothermal carbonization (HTC) technology has been employed to deal with BL and corn stalk (CS) under various conditions. A variety of analytical technologies, including Fourier Transform Infrared Spectrometer, X-Ray Diffraction, element analyzer, comprehensive thermal analyzer, scanning electron microscope, chromatography/mass spectrometry, TOC analyzer, and density functional theory (DFT), were used to characterize the physicochemical properties of hydrochar and aqueous phase product. The effects of experimental parameters (temperature, solid-liquid ratio, and time) on the HTC of BL and CS were systematically investigated. The higher energy yield and densification of hydrochar prepared by our HTC technology were obtained at 260 ℃ in 30 min with a solid-liquid ratio of 1:3. Mechanism study indicates that NaOH, which comes from the original BL, could effectively facilitate the cleavage of β–O–4 bond in lignin and β–1–4 glycosidic bond in cellulose and hemicellulose molecules. Hemicellulose and cellulose are more susceptible to degradation relevant to the lignin in the presence of NaOH. Elementary analysis shows that the dosage of BL is important for improving energy densification of hydrochar. The combustion characteristics show that hydrochar presents a thermochemical behavior, which is close to bituminous coal. Owing to hydroxyl ion in NaOH ion pair was consumed in the series of dehydrogenation reactions, pH of HTC aqueous phase product significantly decreases from 11 to 13 in original BL to 4.8–5. Such results indicate that a completely change for the components of BL could be obtained by our HTC technology, which provide a novel idea for the treatment of Papermaking BL without concentration.

Self-assembling chitosan based injectable and expandable sponge with antimicrobial property for hemostasis and wound healing

Chitosan and chitosan derivative are widely used in hemostasis, antibiosis and wound repair for its good biocompatibility and unique effect. However, the preparation of chitosan based hemostatic materials or wound dressings generally involves chemical crosslinking agent introduction, acid residue or complicated preparation process, which limits its clinical application. In this study, an injectable and expandable chitosan sponge was constructed by chitosan (CS) and quaternized chitosan (QCS) self-assembly without acid retention and chemical crosslinker introduction. In the neutral condition, the hydrogen bond of CS molecules can act as the driving force to form cross-linking network, and the QCS was introduced to regulate the hydrogen bond of CS to avoid the excessive aggregation. The porous QCS/CS sponge was obtained by freeze-drying of the self-assembly QCS/CS hydrogel. The sponge exhibited high expansibility, injectability and water/blood triggered shape memory property. Due to the introduction of QCS, the sponge showed good antibacterial properties, which can protect the wound from bacterial invasion. The convenient and green preparation method of injectable and expandable QCS/CS sponge is a potential method for the treatment of hemostasis and wound healing.

Enhanced saccharification levels of corn starch using as a strategy a novel amylolytic complex (AmyHb) from the thermophilic fungus Humicola brevis var. thermoidea in association with commercial enzyme.

Amylases represent a versatile group of catalysts that are used for the saccharification of starch because they can hydrolyze the glycosidic bonds of starch molecules to release glucose, maltose, and short-chain oligosaccharides. The amylolytic complex of the thermophilic filamentous fungus Humicola brevis var. thermoidea (AmyHb) was produced, biochemically characterized, and compared with the commercial amylase Termamyl. In addition, the biotechnological application of AmyHb in starch saccharification was investigated. The highest production was achieved using a wheat bran medium at 50°C for 5-6days in solid-state fermentation (849.6 ± 18.2U·g-1) without the addition of inducers. Optimum amylolytic activity occurred at pH 5.0 at 60°C, and stability was maintained between pH 5.0 and 6.0, with thermal stability at 50-60°C, especially in the presence of Ca2+. These results were superior to those found with Termamyl. Both enzymes were strongly inhibited by Hg2+, Cu2+, and Ag+; however, AmyHb displayed increased activity in the presence of Mn2+ and Na+. In addition, AmyHb showed greater tolerance to a wide range of ethanol concentrations. AmyHb appears to be a complex consisting of glucoamylase and α-amylase, based on its substrate specificity and TLC. The hydrolysis tests on cornstarch flour showed that the cocktail of AmyHb50% + Termamyl50% significantly increased the release of glucose and total reducing sugars (36.6%) when compared to the enzymes alone. AmyHb exhibited promising physicochemical properties and good performance with commercial amylase; therefore, this complex is a biotechnological alternative candidate for the bioprocessing of starch sources.

Study on the efficient electrocatalytic depolymerization of α-O-4 bond in lignin assisted by simple electrolyte

Lignin is anticipated to serve as a replacement for dwindling fossil fuel resources owing to its abundant sources and renewable nature. The electrochemical oxidation technique for depolymerizing lignin has garnered significant interest for its environmentally friendly and mild operating conditions. Nevertheless, the current utilization of auxiliary electrolytes, predominantly organic bases, ionic liquids, and other specialized substances, poses a constraint on the widespread adoption of this approach. Furthermore, there is a scarcity of instances where electrochemical technology has been employed to depolymerize the α-O-4 bond in lignin for the production of highly selective acetals. In this study, a sodium chloride/methanol (NaCl/MeOH) system was utilized for the direct depolymerization of the α-O-4 bond in a lignin model molecule, specifically benzyl phenyl ether (BPE). The optimal conditions resulted in a 95.2 % conversion rate of the BPE substrate and a high yield of 94.5 % for the main product, benzaldehyde dimethyl acetal(Bda). This research offers a promising approach for the electrocatalytic depolymerization of α-O-4 bonds in lignin, leading to the selective production of acetal chemicals using a common auxiliary electrolyte at room temperature in just 2 h.

Identification of Alzheimer’s disease and vascular dementia based on a Deep Forest and near-infrared spectroscopy analysis method

Alzheimer’s disease (AD) and vascular dementia (VaD) typically do not exhibit distinct differences in clinical manifestations and auxiliary examination results, which leads to a high misdiagnosis rate. However, significant differences in treatment approaches and prognosis between these two diseases underscore the critical need for an accurate diagnosis of AD and VaD. In this study, serum samples from 33 patients with AD patients, 37 patients with VaD, and 130 healthy individuals were collected, employing near-infrared aquaphotomics technology in combination with deep learning for differential diagnoses. Through an analysis of water absorption patterns among different diseases via aquaphotomics, the efficacies of traditional machine learning methods (Support Vector Machine and Decision Trees) and deep learning approaches (Deep Forest) in modeling were compared. Ultimately, by leveraging feature extraction techniques in conjunction with deep learning, a differential diagnostic model for AD and VaD was successfully developed. The results revealed that aquaphotomics could identify a certain correlation between the number of hydrogen bonds in water molecules and the development of AD and VaD; the deep learning model was found to be superior to traditional machine learning models, achieving an accuracy of 98.67 %, sensitivity of 97.33 %, and specificity of 100.00 %. The bands identified using the Competitive Adaptive Reweighting Algorithm method, primarily located at approximately 1300–1500 nm, showed a significant correlation with water molecules containing four hydrogen bonds. These results highlighted the potential role of the water molecule hydrogen-bond network in disease development and were consistent with the aquaphotomics analysis results. Therefore, the differential diagnostic model developed by integrating near-infrared spectroscopy and deep learning was proven to be effective and feasible, providing accurate and rapid diagnostic methods for AD and VaD diagnoses.

Hydrogen bond-derived symmetry transformation in hydroxyborates: Converting the nonlinearity from null to active

Non-centrosymmetric structure is the prerequisite to symmetry-dependent properties for functional materials. The inherent tendency of crystallization toward centrosymmetric arrangements has posed a great challenge in nonlinear optical crystals that requires non-centrosymmetric structure. Here we discovered two new hydroxyborates A[C(NH2)3][B4O5(OH)4]·nH2O (A = K, Rb; n = 3, 1.5), which have high similarity in cationic and anionic frameworks but clearly differ in terms of symmetry, such as non-centrosymmetric versus centrosymmetric. Variations in the hydrogen bonds of water molecules in the lattice are confirmed to be the origin of the symmetry breaking and transformation. The effectiveness of hydrogen bond-derived molecular engineering in producing non-centrosymmetric structure and opening up new avenues in the nonlinear optical crystal sector is demonstrated in this work.

Biosynthetic fuels: A marriage of renewable resources and chemical thermodynamics

Terpenes represent a highly diverse group of natural products with wide applications. Terpenoid structures can be derived from different renewable sources and utilized as fuels. Application as fuels requires hydrogenation of the double bonds in the respective molecules to ensure clean combustion. This hydrogenation can be performed either directly with elemental hydrogen or indirectly via transfer hydrogenation with a Liquid Organic Hydrogen Carrier. In this study, the thermochemical fundamentals of these reaction has been evaluated. For this task, for a first time a combination of experimental thermochemistry and quantum-chemical molecular modelling has been applied. The results show the hydrogenation of the respective structures is thermodynamically highly favourable. Correspondingly, dehydrogenation would be comparatively unfavorable. Yet, for a fuel no dehydrogenation is required. As an alternative to conventional hydrogenation, transfer hydrogenation, which is often subject to partial conversions due to limitations by the reaction equilibrium, can be realized with a high degree of conversion. While the entropy of reaction for hydrogen transfer from cyclohexyl-structures to terpene structures is close to zero, the enthalpy of reaction is highly negative. This leads to a Gibbs energy of reaction which is clearly negative and ensures a large thermodynamic driving force for the reaction. As a consequence, downstream processing, which is usually very demanding for transfer hydrogenations, is comparatively easy. These finding underline the great potential of these bio-derived substances for conversion into sustainable fuels.

Theoretical Study on the Effect of Cyano- and Dimethylamine-Group on ESIPT Behavior and Luminescent Properties of Novel Flavone-Based Fluorophore.

Recently, a new fluorescent senor based on 3-hydroxy-2-(naphthalen-2-yl)-4H-chromen-4-one (HFN) for selective detection of H2Sn was obtained in the experiment (Spectrochim. Acta Part A 271(2022)120962). Based on HFN, three new compounds (HFN1, HFN2 and HFN3) are designed to explore the influences of dimethylamine (-N(CH3)2) and cyano (-CN) groups on the excited-state intramolecular proton transfer (ESIPT) process and luminescent features of HFN. After analyzing the mainly geometrical parameters, electron densities and infrared spectra, we discovered that the intramolecular hydrogen bonds (IHBs) in the target molecules become stronger upon photo-excitation. Introducing -CN or/and -N(CH3)2 groups into HFN indeed influences its ESIPT behavior and luminescent properties. The -N(CH3)2 group enhances IHB, reduces ESIPT barrier and caused absorption/ fluorescence (at T form) peak blue-shift, while the -CN group shows a counterproductive effect. The coincidence of -N(CH3)2 and -CN made the absorption/fluorescent wavelength of HFN red-shift more than single -N(CH3)2 or -CN group does.

A Computational Study of Reactions with Boric Acid Aimed to Promote the Utilization of Lignin.

For exploring the reaction between the hydroxyl groups of lignin and boric acid under the alkaline condition, we study three proposed mechanisms for the formation of the anionic borate diester (ABDE) using the salicyl alcohol anion as the model compound by the density functional theory. ABDE has high flame retardancy and is a potentially practical application of lignin. The catalysis of sodium cation is found to enhance the deprotonation of the water cluster. The deprotonated product, hydroxide anion, is essential to the critical step, which is the cleavage of B-O bonds of the boric acid molecule, in reaction mechanisms. The energy profiles of the mechanisms show that the reaction between lignin and boric acid may start from the hydroxymethyl moieties of lignin since it requires less energy for the aforementioned critical step than from the phenol moieties of lignin. Moreover, the hydroxide anions compete with the hydroxymethyl groups in lignin for the formation of B-O bonds by forming tetrahydroxyborate anion (TBA) which requires very high activation energies to further react to the desired product ABDE. The optimal condition is to enhance the catalytic effect of sodium cations and meanwhile to control the formation of TBA.

Improving the Catalytic Efficiency of Electrochemical Nitrogen Reduction Reaction (NRR) through Surface Modification and Nanostructured Bimetallic Catalysts

Electrochemical nitrogen reduction is recognized as a promising and sustainable alternative to the conventional Haber-Bosch method to produce ammonia. However, there are many challenges that pose significant barriers to the practical application of the nitrogen reduction reaction (NRR). These challenges are primarily attributed to the strong triple bond in the N2 molecule and the competing hydrogen evolution reaction (HER). This work investigates the synergy between alloys and nanostructured bimetallic systems and the application of molecular overlayers to improve efficiency and production rate of ammonia on the catalyst surface. We studied the combination of a noble metal catalyst scaffold modified with active metals (Li/Mg) that is known to cleave the N-N bond. Solvent effects were also tested in both aqueous and non-aqueous media to see changes in catalyst effects. Additionally, various experimental controls were performed including argon controls, isotope labeling, and assessing NOX contaminants to ensure that the reaction was interacting with our catalyst. Overall, this work demonstrates the use of molecular overlayers on nanostructured bimetallic systems to control hydrophobicity of catalyst surface and improve faradaic efficiency, ammonia production rate, catalyst durability and current density. Relationships between these parameters helped understand NRR mechanism and will help guide future NRR catalyst design.