Organic electrosynthesis has emerged as a powerful strategy for leveraging electricity in organic synthesis. Despite its growing popularity, the fundamental molecular interactions governing electrochemical systems remain poorly understood. Many electrosynthetic reactions show strong dependence on the identity of the allegedly inert supporting electrolyte, which can significantly impact yields and selectivity, yet the physical origins of these effects are largely unexplored. A mechanistic understanding of electrolyte effects would enable more rational reaction design for applications. Here, we use cyclic voltammetry to investigate cobalt‐based metal–carbon bond homolysis and elucidate how common supporting electrolytes influence reaction rates. Bulk electrolysis experiments further reveal how electrolyte choice affects overall selectivity. Peak‐ratio analysis indicates that Co(Salen)–benzyl bond cleavage proceeds via a reversible homolysis mechanism that becomes rate‐limited by bond dissociation at high substrate concentrations. The reaction rate varies systematically with electrolyte identity, and changes in oxidative addition rates are quantified using simulations. These experimental findings are supported by ab initio and classical molecular dynamics simulations, as well as density functional theory calculations, which provide insights into reaction pathways, energetics, and dynamics. Together, these results demonstrate that electrolyte selection enables rational tuning of reaction rates and downstream selectivity, highlighting the critical role of electrolytes in metal‐catalyzed organic electrosynthesis.

This report describes the design, development, and optimization of an electrochemical deoxyfluorination of arenes using a tetrafluoropyridine-derived leaving group. NEt33HF serves as the fluoride source, and the reactions are conducted using either constant potential or constant current electrolysis in an undivided electrochemical cell. Mechanistic studies support a net oxidative pathway, in which initial single-electron oxidation generates a radical cation intermediate that is trapped by fluoride. The resulting radical undergoes a second oxidation reaction, followed by the loss of the leaving group to yield the fluoroarene product.

Adsorbing polyconjugated carbonyl and aromatic species to Pd nanoparticles forms persistent intermediates that mediate reactions between hydrogen and oxygen-derived species. These surface redox mediators form in situ and increase selectivities toward H2O2 formation (∼65-85%) compared to unmodified Pd nanoparticles (∼45%). Infrared spectroscopy, temperature-programmed oxidation measurements, and ab initio calculations show that these species adsorb irreversibly to Pd surfaces and persist over extended periods of catalysis. Combined rates and kinetic isotope effect measurements and simulations suggest that carbonyl groups of bound organics react heterolytically with hydrogen to form partially hydrogenated oxygenated complexes. Subsequently, these organic species transfer proton-electron pairs to O2-derived surface species via pathways that favor H2O2 over H2O formation on Pd nanoparticles. Computational and experimental measurements show redox pathways mediated by partially hydrogenated carbonyl species form H2O2 with lower barriers than competing processes while also obstructing O-O bond dissociation during H2O formation. For example, adsorption and hydrogenation of hexaketocyclohexane on Pd forms species that react with oxygen with high H2O2 selectivities (85 ± 8%) for 130 h on stream in flowing water without additional promoters or cosolvents. These paths resemble the anthraquinone auto-oxidation process (AAOP) used for industrial H2O2 production. These surface-bound species form partially hydrogenated intermediates that mediate H2O2 formation with high rates and selectivities, comparable to AAOP but on a single catalytic nanoparticle in pure water without organic solvents or multiunit reaction-separation chains. The molecular insights developed herein provide strategies to avoid organic solvents in selective processes and circumvent their associated process costs and environmental impacts.

Creating 1D or 2D extended defects in thin films that propagate throughout the film thickness enables engineering nanoscale materials with anisotropic properties governed by these defects. Performing defect engineering of thin films with location specificity facilitates new nanoscale device architectures that harness the unique properties of these anisotropic extended defects. Here we demonstrate that, by combining Ga focused ion-beam (FIB) exposure and subsequent heat treatment, it is possible to pattern nanoscale structural perturbations on the substrate surface that promote nucleation and propagation of extended defects in thin films epitaxially grown on these substrates. Using SrTiO3 as a substrate for growing perovskite BaSnO3 and SrSnO3 thin films, we demonstrate engineering ultra-high densities of threading 1D dislocations and 2D Ruddlesden-Popper faults with nanometer-level location specificity limited only by the resolution of the patterning Ga ion-beam of the FIB. Given the versatility of this method, it can be applied to different substrates and films, serving as a flexible means of defect-driven material engineering.

This report describes an investigation of the role of H2O and DMF (N,N-dimethylformamide) as solvents on the electrochemical oxidation of oxalate (C2O42–). In H2O/0.1 M Na2SO4, the 2e– oxidation of C2O42– yields two CO2 molecules via a classical ECE mechanism, resulting in a single oxidation wave at 1.2 V vs Ag/AgCl. In contrast, two distinct oxidation waves are observed in DMF/0.1 M TBAP at ~0.1 V and ~0.7 V vs Ag/AgCl. The second wave at more positive potentials in DMF was first assigned by Maran and co-workers to the oxidation of the adduct C2O42–•CO2 formed from generation of CO2 during the first wave. Electronic interaction of C2O42– and CO2 stabilizes C2O42–, making it more difficult to oxidize than free C2O42–. Herein, we present cyclic voltammetry (CV), finite difference (FD) simulations, Raman spectroscopy, and ab initio molecular dynamics (AIMD) simulations to determine the thermodynamics and kinetics of C2O42–•CO2 formation, as well as the adduct structure. FD simulations of the voltammetric data provide approximate thermodynamic and kinetic parameters for C2O42–•CO2 formation in DMF, as well as a new value for the diffusion coefficient of C2O42– in DMF that differs substantially from previously reported values. Raman spectroscopy directly demonstrates C2O42–•CO2 formation in DMF, while AIMD simulations predict that the solvent-dependent thermodynamics and mechanism for C2O42– oxidation can be explained by C2O42––solvent and C2O42––CO2 interactions. A by-product of this investigation is the prediction from AIMD simulations that the C2O42–•CO2 interaction in DMF destabilizes CO2. Consistent with this finding, cyclic voltammetry demonstrates that the thermodynamic potential for CO2 reduction in DMF at a Hg electrode decreases by ~0.3 V upon addition of C2O42– to the solution.

This report describes the design, development, and optimization of an electrochemical deoxyfluorination of arenes using a tetrafluoropyridine-derived leaving group. NEt3·3HF serves as the fluoride source, and the reactions are conducted using either constant potential or constant current electrolysis in an undivided electrochemical cell. Mechanistic studies support a net oxidative pathway, in which initial single-electron oxidation generates a radical cation intermediate that is trapped by fluoride. The resulting radical undergoes a second oxidation reaction, followed by the loss of the leaving group to yield the fluoroarene product.

Selective C-H bond activation is one of the most critical molecular transformations in synthesizing chemicals, pharmaceuticals, and natural product intermediates with broad applications. Recent efforts have focused on developing electrocatalytic mediators that rapidly and selectively activate specific C-H bonds. These mediated activations offer multiple benefits over direct electrochemical oxidation as they can occur at lower overpotentials, leading to higher faradaic efficiency and selectivity with reduced solvent oxidation. Our previous work described the development of N-alkyl ammonium ylides as a new class of electro-oxidative mediators. Despite its importance, the underlying principles of designing efficient mediators and understanding their site-selectivity are yet to be fully elucidated. The work discussed herein scrutinized mediator design using density functional theory calculations to highlight the critical features of mediators that govern C(sp3)-H activation. The design of newer mediators is guided by scaling relationships between the thermodynamic descriptors associated with the elementary steps involved in C(sp3)-H activation. We subsequently examine the results from detailed transition state calculations to elucidate the site-selectivity for C(sp3)-H activation for various substrates with quinuclidine and ylide mediators. The results show the critical interplay of thermodynamic, steric, and electronic features of the substrate and mediator that govern the corresponding site-selectivity. Finally, we present unifying trends across multiple substrates and mediators to understand the site-selectivity for mediated electrocatalytic C(sp3)-H activations and push our efforts toward predicting regio-selectivity in the future.

Aqueous solutions containing both the strong oxidant, peroxydisulfate (S2O82‒), and the strong reductant, oxalate (C2O42‒), are thermodynamically unstable due to the highly exothermic homogeneous redox reaction: S2O82‒ + C2O42‒ ® 2 SO42‒ + 2 CO2 (DG0 = −490 kJ/mol). However, at room temperature, this reaction does not occur to a significant extent over the timescale of a day due to its inherently slow kinetics. We demonstrate that the S2O82‒/C2O42‒ redox reaction occurs rapidly, once initiated by the Ru(NH3)62+-mediated 1e– reduction of S2O82‒ to form S2O83•‒ at a glassy carbon electrode. Theoretically, the mediated electrochemical generation of a single molecule of S2O83•‒ is capable of initiating an autocatalytic cycle that consumes both S2O82‒ and C2O42‒ in bulk solution. Several experimental demonstrations of S2O82‒/C2O42‒ autocatalysis are presented. Differential electrochemical mass spectrometry measurements demonstrate that CO2 is generated in solution for at least 10 minutes following a 30-s initiation step during which S2O83•‒ is generated. Quantitative bulk electrolysis of S2O82‒ in solutions containing excess C2O42‒ is initiated by electrogeneration of immeasurably small quantities of S2O83•‒. Capture of CO2 as BaCO3 during electrolysis additionally confirms the autocatalytic generation of CO2. First- principles density functional theory calculations, ab initio molecular dynamics simulations, and finite difference simulations of cyclic voltammetric responses are presented that support and provide additional insights into the initiation and mechanism of the S2O82‒/C2O42‒ autocatalytic reaction. Preliminary evidence indicates that autocatalysis also results in a chemical traveling reaction front that propagates into the solution normal to the planar electrode surface.

Carbon-halogen bond cleavage has been studied extensively for many years as a simple electrosynthesis step in the formation of more complex natural products. Reduction of halogenated phenols has received less attention, in part, due to the lowered faradaic efficiency resulting from the competing hydrogen evolution reaction. Herein, we report the electro-reduction of a series of brominated phenols through a homogeneous electrocatalytic (EC') mechanism. Beginning with the structurally simple 2-bromophenol, we use foot-of-the-wave analysis to determine optimal catalysts. Nickel(II) salen requires the lowest overpotential for C-Br reduction and was used across all substrates. Chronoamperometric studies and density functional theory calculations were carried out to contribute to our understanding of the reduction mechanism. Next, the more complex 2,6-dibromophenol and tetrabromobisphenol-A are studied by means of cyclic voltammetry, chronoamperometry, and density functional theory. Through analysis of molecular orbitals diagrams, the more complex brominated phenols are found to undergo sequential carbon-bromine bond reduction, wherein the electrogenerated radical species accepts a second electron to form a carbanion before second carbon-bromine bond cleavage occurs.

Layered black arsenic (b-As) has recently emerged as a new anisotropic two-dimensional (2D) semiconducting material with applications in electronic devices. Understanding factors affecting the ambient stability of this material remains crucial for its applications. Herein we use first-principles density functional theory (DFT) calculations to examine the stability of the (010) and (101) surfaces of b-As in the presence of oxygen (O2) and water (H2O). We show that the (101) surface of b-As can easily oxidize in presence of O2. In the presence of moisture contained in air, the oxidized b-As surfaces favorably react with H2O molecules to volatilize As in the form of As(OH)3 and AsO(OH), which results in the degradation of the b-As surface, predominantly across the (101) surface. These predictions are in good agreement with experimental electron microscopy observations, thus demonstrating the co-operative reactivity of O2 and H2O in the degradation of layered b-As under ambient conditions.

Alcohol oxidation is an important class of reaction that is traditionally performed under harsh conditions and most often requires the use of organometallic compounds or transition metal complexes as catalysts. Here, we introduce a new electrochemical synthetic method, referred to as reductive oxidation, in which alcohol oxidation is initiated by the redox-mediated electrocatalytic reduction of peroxydisulfate to generate the highly oxidizing sulfate radical anion. Thus, and counter-intuitively, alcohol oxidation occurs as a result of an electrochemical reduction reaction. This approach provides a selective synthetic route for the oxidation of alcohols carried out under mild conditions to aldehydes, ketones, and carboxylic acids with up to 99% conversion yields. First-principles density functional theory calculations, ab initio molecular dynamics simulations, cyclic voltammetry, and finite difference simulations are presented that support and provide additional insights into the S2O82--mediated oxidation of benzyl alcohol to benzaldehyde.

The “magic methyl” effect – a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group – provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)–H methylation of structurally complex medicinal agents remain very limited. In this work, we disclose a modular, efficient, and selective strategy for the α-methylation of protected amines (i.e., amides, carbamates, and sulfonamides) by means of electrochemical oxidation. Mechanistic analysis guided our development of an improved electrochemical protocol on the basis of the classic Shono oxidation reaction, which features broad reaction scope, high functional group compatibility, and operational simplicity. Importantly, this reaction system is amenable to the late-stage functionalization of complex targets containing basic nitrogen groups that are prevalent in medicinally active agents. When combined with organozinc-mediated C–C bond formation, our protocol enabled the direct methylation of a myriad of amine derivatives including those that have previously been explored for the “magic methyl” effect. This synthetic strategy thus circumvents multistep de novo synthesis that is currently necessary to access such compounds and has the potential to accelerate drug discovery efforts.

The direct, transition metal-catalyzed carboxylation of organohalides with carbon dioxide is a highly desirable transformation in organic synthesis as it utilizes feedstock chemicals and delivers carboxylic acids –among the most utilized class of organic molecules. Phenyl acetic acids, in particular, are privileged motifs that appear in many pharmaceuticals and biologically active compounds. This article reports the development of a sustainable and selective cobalt-catalyzed electrochemical carboxylation of benzyl halides with CO2 to generate phenyl acetic acids. The success of this transformation is enabled by the development of low-coordinate cobalt/pyrox complexes as electrocatalysts to convert various benzyl chlorides and bromides to their corre-sponding phenyl/heteroaryl acetic acids with high selectivity over undesired homocoupling of the benzyl halides. The combina-tion of electroanalytical methods, simulation studies, control reactions, and first-principles density functional theory (DFT) calculations informed the mechanistic analysis of this reaction. An EC’C-type activation mechanism of benzyl halides, which is unique to Co(II)/pyrox electrocatalysts, provides the rationalization of the exceptional observed selectivity for carboxylation. Specifically, the Co(II)/pyrox catalyst undergoes reduction to Co(I) followed by halogen abstraction and a favorable radical rebound to Co(II)/pyrox to form alkyl–Co(III) intermediates. Although voltammetry only shows a single electron transfer step, bulk electrolysis shows a two electron process and using DFT calculations, the intermediates are proposed to undergo two-electron reduction to alkyl–Co(I) followed by a ZnCl2-assisted CO2 insertion to form the carboxylated adducts with regenera-tion of Co(I)/pyrox.

The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organicsynthesis. From simplifying access to metabolites and late-stage diversification of lead compoundsto truncating retrosynthetic plans, there is a growing need for new reagents and methods forachieving such a transformation in both academic and industrial circles. One main drawback ofcurrent chemical reagents is the lack of diversity with regards to structure and reactivity thatprevent a combinatorial approach for rapid screening to be employed. In that regard, directedevolution still holds the greatest promise for achieving complex C–H oxidations in a variety ofcomplex settings. Herein we present a rationally designed platform that provides a step towardsthis challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific,chemoselective C(sp3)–H oxidation. By taking a first-principles approach guided by computation,these new mediators were identified and rapidly expanded into a library using ubiquitous buildingblocks and trivial synthesis techniques. The ylide-based approach to C–H oxidation exhibitstunable selectivity that is often exclusive to this class of oxidants and can be applied to real worldproblems in the agricultural and pharmaceutical sectors.

In the present study, stable sodium plating/stripping has been achieved on a bare aluminum current collector, without any surface modifications or artificial SEI deposition. The crucial role of predeposited sodium using cyclic voltammetry on bare aluminum as a matrix for plating/stripping has been highlighted using different protocols for cycling. The predeposition strategy ensures stable and efficient cycling of sodium in anode-free sodium batteries without dendritic formations. The study highlights the difference of sodium plating/stripping in carbonate and glyme solvent electrolytes on the bare aluminum current collector. Contrary to the carbonate solvent electrolyte, the cell with the tetraglyme solvent electrolyte and sodium loading of 1 mA h/cm2 has an overpotential under 20 mV during the sodium plating/stripping cycles at 0.5 mA/cm2 for a testing period of 650 h. Overpotentials under 40 and 100 mV have been achieved at current densities up to 1 and 2 mA/cm2 for loadings up to 5 and 10 mA h/cm2, respectively, for a testing time up to 1500 h. Density functional theory simulations have been performed to obtain the solvation energies, and the highest occupied molecular orbital-lowest unoccupied molecular orbital band gap of the solvent-sodium ion complexes for the glyme solvent electrolytes and their trends have been correlated with the experimental observations.

Lithium-ion batteries are being extensively used as a cleaner source of energy in EVs and HEVs as well as in portable electronic devices. A proper charging mechanism is necessary to ensure safe and efficient operation of the battery. Constant current (CC), constant currentconstant voltage (CC-CV) and multistage constant current-constant voltage (MSCC-CV) charging algorithms are the commonly used mechanisms. The magnitude of charging current to be applied, duration of application and end-of-charge voltage, however, are based on heuristics/estimates which do not account for the impact these factors have on charging time, lifetime of the battery and safety of operations [1]. Equivalent electric circuit models for the battery have been used recently to optimize the charging process of a battery. Optimal charging current of a lithium-ion battery was determined considering multiple objective functions namely time of charge, temperature rise and energy loss [2]. The resultant multi-objective optimization problem was converted into a single objective problem using the weighted sum approach. Perez et al. [1] used similar approach, however, the objectives considered were different, namely, reduction in state of health of the battery (SOH) and time of charge. In the present work, we have used a first principles based charge-discharge model to perform a cycle life study [3]. During the charging process, formation of SEI layer on anode particles irreversibly consumes the active lithium ions, accounting for the cycle life aging. The above model considering simultaneous transport of ions in both solid and electrolyte phase is then being optimized for a fixed number of charge-discharge cycles considering different charging mechanisms. The optimization yields the profile of charge-discharge current with time which minimizes the four objectives, i.e., time of charge, energy loss, temperature rise and aging of the battery. Instead of performing a single-objective optimization, we chose multi-objective optimization to simultaneously minimize all the four factors stated above, which gives a set of Pareto optimal charge-discharge current profiles. Pareto optimal profiles obtained this way can be used as set points in a Battery Management System providing adaptive charging-discharging strategies based on the cycle requirements and battery specifications. For e.g., while a mechanism involving higher charging currents is useful for charging during daytime operation of an EV to reduce the charging time; low charging currents during the non-operational hours reduces the energy loss, temperature rise and the aging. The profile thus obtained ensures an efficient and robust usage of the battery.

The widely used Koros-Nowak criterion and Madon-Boudart test which are based on intra-particle dilution effects have been extended by various researchers to study inter-particle dilution effects. In this work, numerical simulations are performed to investigate the inter-particle dilution effects in a packed bed containing catalyst and inert particles. It is shown that if the turnover rate is found to be independent of the inter-particle dilution ratio, it does not necessarily imply that the diffusional limitations are absent, i.e., if the Madon-Boudart test which was originally developed on the basis of intra-particle dilution is used to study inter-particle dilution effects, the results could be error prone. We show that a straight line with a slope of 1 on a log-log scale between the reaction rate and the weight of the catalyst, or a constant turnover rate with respect to catalyst particle number density does not always imply that the diffusional limitations are absent. It is also emphasized that maintaining low conversions does not always ensure the absence of diffusional limitations.