Electrochemical Synthesis Research Articles

Electrochemical Synthesis of Phosphorylated Indoles and Trp-Containing Oligopeptides.

Cp2Fe-mediated electrochemical synthesis of phosphorylated indoles and Trp-containing oligopeptides has been developed, which eliminates the need for external oxidants and yields the desired products in moderate to excellent yields under mild conditions. Importantly, the synthetic applicability was further demonstrated through its easy scalability and the anticancer activity of the product. Remarkably, it presents the first electrochemical protocol to access the phosphorylation of indoles and Trp-containing oligopeptides.

Cocos nucifera-mediated electrochemical synthesis and coating of CuO/ZnO nanostructures on Fe ship strips for marine application

ABSTRACT Copper oxide and zinc oxide nanoparticles (Nanostructures) were synthesized using a greener electrochemical approach using Cocos nucifera (Coir) extract and deposited on Fe ship strip (FSS). These corrosion inhibitor films were characterized by XRD, SEM, BET, Raman Spectroscopy, FTIR spectroscopy, and TGA analysis. An electrochemical corrosion test was performed for the coated samples with 3.5% NaCl as electrolyte and compared with uncoated samples. The corrosion rate was tested using the Tafel slope and the interpolation between the log of current and voltage proves that the corrosion rate in the CuO-coated sample was lower than that of the ZnO-coated sample which can be attributed to the porosity of the ZnO film showing 0.8–0.95 P/P0 as observed for 6 cm2 as inferred from BET analysis. The Nyquist plot suggests the corrosion inhibition rate of the CuO-coated film in 3.5% NaCl is improved by a factor of 3 compared to the uncoated sample (0.9 mA/year for FSS where for the CuO-coated samples 0.3 mA/year). The result of the antifouling behavior of CuO/ZnO coatings using the BIOVIA simulation tool showed the repulsion of homology-modeled protein Aacp20k, an attachment protein found in Amphibalanus Amphitrite which is a most prominent foul species.

Recent Advances in Applied Electrochemistry: A Review

Applied electrochemistry (AE) plays today an important role in a wide range of fields, including energy conversion and storage, processes, environment, (bio)analytical chemistry, and many others. Electrochemical synthesis is now proven as a promising pathway to avoid all disadvantages in terms of high energy consumption and high pollution, while electrochemical modeling becomes a powerful tool to understand complex systems and predict and optimize the electrochemical devices under various conditions, which reduce study time and cost. The vital role of electrochemistry will greatly be considered in the upcoming years, aiming to reduce carbon footprints and supporting the transition towards a green and more sustainable energy framework. This review article summarizes the recent advances in applied electrochemistry. It shows how this field has become an indispensable tool for innovation, progress, problem-solving in the modern world, and addressing societal challenges across diverse fields.

Electrochemical Synthesis of C(sp3)‐Rich Amines by Aminative Carbofunctionalization of Carbonyl Compounds

AbstractAlkylamines form the backbone of countless nitrogen‐containing small molecules possessing desirable biological properties. Despite advances in amine synthesis through transition metal catalysis and photoredox chemistry, multicomponent reactions that leverage inexpensive materials to transform abundant chemical feedstocks into three‐dimensional α‐substituted alkylamines bearing complex substitution patterns remain scarce. Here, we report the design of a catalyst‐free electroreductive manifold that merges amines, carbonyl compounds and carbon‐based radical acceptors under ambient conditions without rigorous exclusion of air and moisture. Key to this aminative carbofunctionalization process is the chemoselective generation of nucleophilic α‐amino radical intermediates that readily couple with electrophilic partners, providing straightforward access to architecturally intricate alkylamines and drug‐like scaffolds which are inaccessible by conventional means.

Spatially Confined Radical Addition Reaction for Electrochemical Synthesis of Carboxylated Graphene and its Applications in Water Desalination and Splitting.

Due to the chemical stability of graphene, synthesis of carboxylated graphene still remains challenging during the electrochemical exfoliation of graphite. In this work, a spatially confined radical addition reaction which occurs in the sub-nanometer scaled interlayers of the expanded graphene sheets for the electrochemical synthesis of highly stable carboxylated graphene is reported. Here, formate anions act as both intercalation ions and co-reactant acid for the confinement of electro-generated carboxylic radical (●COOH) in the sub-nanometer scaled interlayers, which facilitates the radical addition reaction on graphene sheets. The controllable carboxylation of graphene is realized by tuning the concentration of formate anions in the electrolyte solution. The high crystallinity of the obtained product indicates the occurrence of spatially confined ●COOH addition reaction between the sub-nanometer interlayers of expanded graphite. In addition, the carboxylated graphene have been used for water desalination and hydrogen/oxygen reduction reaction. Therefore, this work provides a new method for the in situ preparation of functionalized graphene through the electrolysis and its applications in water desalination and hydrogen/oxygen reduction reactions.

Oxygen vacancies enhanced photo-fenton-like catalytic degradation of rhodamine B by electrochemical synthesized α-Fe2O3 nanoparticles

Hematite is widely used as a catalyst in a photo-Fenton-like process for the oxidation of dyes. We report on the electrochemical synthesis of α-Fe2O3 nanoparticles. The structure, morphology, chemical composition, and surface chemical state of the catalyst, as well as its optical and magnetic properties, were thoroughly characterized by scanning electron microscopy, X-ray diffraction spectroscopy (XRD), shift combination scattering spectroscopy, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). It was found that the crystal size was 63.9 nm. It was shown that the presence of Fe2+ on the surface was due to oxygen vacancies rather than impurity phases. The optical bandgap was determined to be 1.87 eV. Nanoparticles exhibit weak ferromagnetic behavior with a magnetization of 1.09 emu/g at maximum applied magnetic field 1 kOe. The catalytic activity in the photo-Fenton-like process for the degradation of Rhodamine B (RhB) dye was investigated, and the effect of working parameters, including H2O2 concentration, catalyst concentration, and RhB concentration, on the degradation efficiency was studied. The maximum degradation rate was 99.15 % in 12 min under optimal conditions. The catalyst showed long-term stability over 5 repeated cycles.

Combined anodic and cathodic peroxide production in an undivided carbonate/bicarbonate electrolyte with 144% combined current efficiency

In recent years, the electrochemical synthesis of peroxides has attracted renewed interest as a potential environmentally friendly production compared to the established anthraquinone process. In addition, it is possible to produce the peroxides directly on site, eliminating the need for expensive and hazardous transportation and storage. Cathodic production of hydrogen peroxide from oxygen is already quite well developed. Anodic production from water, on the other hand, is still facing significant challenges, despite its historic pioneering role. In this manuscript we show that anodic and cathodic synthesis of peroxides can even be combined to achieve greater than 100% current efficiency (CE) due to the combined effect of both half-reactions. So far, similar devices have always employed different electrolytes for each, which necessitated the use of a membrane and posed contamination risk. However, herein we show that both half-reactions can also employ the same electrolyte. This enables even an undivided cell, omitting the need for the expensive membranes. Despite its simplicity, this setup yielded an outstanding performance with a combined CE of 144%.

Recent Progress in Electrochemical Synthesis and Conversion of Nitrates in Aqueous Electrolyte

Recent Progress in Electrochemical Synthesis and Conversion of Nitrates in Aqueous Electrolyte

An ambipolar PEDOT-perfluorinated porphyrin electropolymer: application as an active material in energy storage systems.

The development of functional organic materials is crucial for the advancement of various fields, such as optoelectronics, energy storage, sensing, and biomedicine. In this context, we successfully prepared a stable ambipolar perfluoroporphyrin-based polymeric film by electrochemical synthesis. Our strategy involved the synthesis of a novel tetra-pentafluorophenyl porphyrin covalently linked to four 3,4-ethylenedioxythiophene (EDOT) moieties. The resulting monomer, EDOT-TPPF16, was obtained through a straightforward synthetic approach with a good overall yield. The unique molecular structure of EDOT-TPPF16 serves a dual function, with EDOT moieties allowing electropolymerization for polymeric film formation, while the electron-acceptor porphyrin core enables electrochemical reduction and electron transport. The electrochemical polymerization permits the polymer (PEDOT-TPPF16) synthesis and film formation in a reproducible and controllable manner in one step at room temperature. Spectroelectrochemical experiments confirmed that the porphyrin retained its optoelectronic properties within the polymeric matrix after the electrochemical polymerization. The obtained polymeric material exhibited stable redox capabilities. Current charge-discharge cycles and electrochemical impedance spectroscopy of the electrochemically generated organic film demonstrated that the polymer could be applied as a promising active material in the development of supercapacitor energy storage devices.

NbC Nanoparticles Decorated Carbon Nanofibers as Highly Active and Robust Heterostructural Electrocatalysts for Ammonia Synthesis.

Transition-metal carbides with metallic properties have been extensively used as electrocatalysts due to their excellent conductivity and unique electronic structures. Herein, NbC nanoparticles decorated carbon nanofibers (NbC@CNFs) are proposed as an efficient and robust catalyst for electrochemical synthesis of ammonia from nitrate/nitrite reduction, which achieves a high Faradaic efficiency (FE) of 94.4% and a large ammonia yield of 30.9 mg h-1 mg-1cat.. In situ electrochemical tests reveal the nitrite reduction at the catalyst surface follows the *NO pathway and theoretical calculations reveal the formation of NbC@CNFs heterostructure significantly broadens density of states nearby the Fermi energy. Finite element simulations unveil that the current and electric field converge on the NbC nanoparticles along the fiber, suggesting the dispersed carbides are highly active for nitrite reduction.

Electrochemical syntheses and characterization of some polydyes and their application for the simultaneous determination of ascorbic acid and uric acid

Electrochemical syntheses and characterization of some polydyes and their application for the simultaneous determination of ascorbic acid and uric acid

Effects of porous structure and oxygen functionalities on electrochemical synthesis of hydrogen peroxide on ordered mesoporous carbon

Two-electron oxygen reduction reaction (2e− ORR) is a promising alternative to energy-intensive anthraquinone process for hydrogen peroxide (H2O2) production. Metal-free nanocarbon materials have garnered intensive attention as highly prospective electrocatalysts for H2O2 production, and an in-depth understanding of their porous structure and active sites have become a critical scientific challenge. The present research investigates a range of porous carbon catalysts, including non-porous, microporous, and mesoporous structures, to elucidate the impacts of porous structures on 2e− ORR activity. The results highlighted the superiority of mesoporous carbon over other porous materials, demonstrating remarkable H2O2 selectivity. Furthermore, integration of X-ray photoelectron spectroscopy (XPS) data analysis with electrochemical assessment results unravels the moderate surface oxygen content is the key to increase 2e− ORR activity. These results not only highlight the intricate interplay between pore structure and oxygen content in determining catalytic selectivity, but also enable the design of carbon catalysts for specific electrochemical reactions.

Regulating Interfacial Microenvironment in Aqueous Electrolyte via a N2 Filtering Membrane for Efficient Electrochemical Ammonia Synthesis.

Electrochemical synthesis of ammonia (NH3) in aqueous electrolyte has long been suffered from poor nitrogen (N2) supply owing to its low solubility and sluggish diffusion kinetics. Therefore, creating a N2 rich microenvironment around catalyst surface may potentially improve the efficiency of nitrogen reduction reaction (NRR). Herein, a delicately designed N2 filtering membrane consisted of polydimethylsiloxane is covered on catalyst surface via superspreading. Because this membrane let the dissolved N2 molecules be accessible to the catalyst but block excess water, the designed N2 rich microenvironment over catalyst leads to an optimized Faradaic efficiency of 39.4% and an NH3 yield rate of 109.2µgh-1mg-1, which is superior to those of the most report metal-based catalysts for electrochemical NRR. This study offers alternative strategy for enhancing NRR performance.

High yield electrosynthesis of oxygenates from CO using a relay Cu-Ag co-catalyst system

As a sustainable alternative to fossil fuel-based manufacture of bulk oxygenates, electrochemical synthesis using CO and H2O as raw materials at ambient conditions offers immense appeal. However, the upscaling of the electrosynthesis of oxygenates encounters kinetic bottlenecks arising from the competing hydrogen evolution reaction with the selective production of ethylene. Herein, a catalytic relay system that can perform in tandem CO capture, activation, intermediate transfer and enrichment on a Cu-Ag composite catalyst is used for attaining high yield CO-to-oxygenates electrosynthesis at high current densities. The composite catalyst Cu/30Ag (molar ratio of Cu to Ag is 7:3) enables high efficiency CO-to-oxygenates conversion, attaining a maximum partial current density for oxygenates of 800 mA cm−2 at an applied current density of 1200 mA cm−2, and with 67 % selectivity. The ability to finely control the production of ethylene and oxygenates highlights the principle of efficient catalyst design based on the relay mechanism.

Influence of Water Hardness and Complexing Agents on Electrochemical Hydrogen Peroxide Generation.

Recently, many studies have been published regarding electrochemical oxygen reduction reaction for generating hydrogen peroxide (H2O2) using gas diffusion electrodes (GDEs) for various applications. Sodium salts solved in deionized water were usually used as supporting electrolytes. In technical applications, however, tap water-based electrolytes with hardeners are particularly relevant and have only been considered in a few studies to date. In this work, we investigated the influence of hardeners on H2O2-generation at 150mAcm‑2 and were able to show that scaling occurs predominantly on the GDE surface and not in its pore structure. With the novel method in electrochemical synthesis by using complexing agents to bind hardeners, we were able to significantly reduce the scaling. Even after 10h of operation, the reactor still achieves a faradaic efficiency (FE) of above 70% (> 67 mg h-1 cm-2), comparable to the experiments without hardeners and complexing agents in the electrolyte. Furthermore, we demonstrate that the complexing agents are not electrochemically converted at the carbon-based GDE and behave inertly. If the cell is operated with complexing agents and rinsed with acidic liquid (anolyte) between batches, scaling can be completely avoided.

A Review of the Effect of Different Electrolytes on the Synthesis of Graphene Sheets by Electrochemical Exfoliation

Graphene oxide (GO) possess some excellent properties that fulfil various applications. Hummers’ method has been used in GO synthesis for years but some issues such as high-cost GO synthesis, the use of toxic chemicals and low yield of GO are still remains and concerned. In addition, this method spends very long time to be completed and subjected to thorough cleaning process to remove toxic chemicals. On the other hand, the electrochemical method saves time, has no explosion risk, releases no toxic gases, and keep safe environmental. The demand of GO supply is crucial particularly important in applications such as energy storage in automobiles thus, a large scale and cheap production of GO is needed. It is reported that the electrochemical synthesis of GO has more benefits such as rapid synthesis, low cost and environmentally friendly than Hummers’ method, therefore, the impact of different electrolytes is important to be studied. Herein, various research works about the electrochemical synthesis of GO are reviewed, precisely involving the anodic exfoliation of graphite, exfoliation mechanism and effects of exfoliation parameters.

Electrochemical Synthesis and Performance of AgCl/Ag/Sliver Mesh Collector Composite Electrode for Seawater Batteries

High-energy-density and easy-to-implement battery storage technologies are essential for the exploitation of marine resources. AgCl is a promising cathode material for seawater batteries due to its environmental friendliness and high capacities density, but its inherent low conductivity limits its application in specific scenarios. In this paper, AgCl was electrochemically grown on a sparsely conductive Ag/Sliver mesh collector (SMC) substrate, and an excellent performance AgCl/Ag/SMC composite electrode is obtained. The cathodic polarization curves indicate that the current density of the AgCl/Ag/SMC electrode was 208.2 mA cm−2 at 0.4 V (vs RHE) potential, which is significantly higher than that of the conventional AgCl cathode material. The AgCl/Ag/SMC electrode demonstrated a very high discharge capacity of 181.7 mAh g−1 at 30 mA cm−2, and the assembled cell was found to be in good condition at 100 mA cm−2 with a power density of up to 154.7 mW cm−2, showing very excellent performance. Furthermore, investigation of the mechanism and depth of discharge experiment reveal the kinetic and microscopic reasons for the high performance of AgCl/Ag/SMC composite electrodes. Therefore, this study provides an efficient and feasible solution for the electrochemical preparation of highly active cathode materials for Mg-AgCl seawater batteries.

Surface Reconstruction for Selective Oxidation of Tetrahydroisoquinoline.

Integration of hydrogen evolution with the oxidation of organic substances in one electrochemical system is highly desirable. However, achieving selective oxidation of organic substances in the integrated system is still highly challenging. In this study, a phosphorylated NiMoO4 nanoneedle-like array was designed as the catalytic active electrode for the integration of highly selective electrochemical dehydrogenation of tetrahydroisoquinolines (THIQs) with hydrogen production. The leaching of anions, including MoO42- and PO43-, facilitates the reconstruction of the catalyst. As a result, nickel oxyhydroxides with the doping of PO43- and richness of defects are in situ formed. In situ Raman and density functional theory calculations have shown that the high catalytic activity is attributed to the in situ formed PO43- involved NiOOH substance. In the dehydrogenation process, the involved C-H bond but not the N-H bond is first destroyed. A two-electrode system was then fabricated with the optimized electrode that shows a benchmark current density of 10 mA cm-2 at 1.783 V, providing a yield of 70% for dihydroisoquinolines. A robust stability was also shown for this integrated electrochemical system. The understanding of the reconstruction behavior and the achievement of selective dehydrogenation will provide some hints for electrochemical synthesis.

Wafer-scale fabrication of mesoporous silicon functionalized with electrically conductive polymers

The fabrication of hybrid materials consisting of nanoporous hosts with conductive polymers is a challenging task, since the extreme spatial confinement often conflicts with the stringent physico-chemical requirements for polymerization of organic constituents. Here, several low-threshold and scalable synthesis routes for such hybrids are presented. First, the electrochemical synthesis of composites based on mesoporous silicon (pSi) and the polymers PANI, PPy and PEDOT is discussed and validated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Polymer filling degrees of ≥74 % are achieved. Second, the production of PEDOT/pSi hybrids, based on the solid-state polymerization (SSP) of DBEDOT to PEDOT is shown. The resulting amorphous structure of the nanopore-embedded PEDOT is investigated via in-situ synchrotron-based X-ray scattering. In addition, a twofold increase in the electrical conductivity of the hybrid compared to the porous silicon host is shown, making this system particularly promising for thermoelectric applications.

Highly Selective Electrochemical Baeyer-Villiger Oxidation through Oxygen Atom Transfer from Water.

The Baeyer-Villiger oxidation of ketones is a crucial oxygen atom transfer (OAT) process used for ester production. Traditionally, Baeyer-Villiger oxidation is accomplished by thermally oxidizing the OAT from stoichiometric peroxides, which are often difficult to handle. Electrochemical methods hold promise for breaking the limitation of using water as the oxygen atom source. Nevertheless, existing demonstrations of electrochemical Baeyer-Villiger oxidation face the challenges of low selectivity. We report in this study a strategy to overcome this challenge. By employing a well-known water oxidation catalyst, Fe2O3, we achieved nearly perfect selectivity for the electrochemical Baeyer-Villiger oxidation of cyclohexanone. Mechanistic studies suggest that it is essential to produce surface hydroperoxo intermediates (M-OOH, where M represents a metal center) that promote the nucleophilic attack on ketone substrates. By confining the reactions to the catalyst surfaces, competing reactions (e.g., dehydrogenation, carboxylic acid cation rearrangements, and hydroxylation) are greatly limited, thereby offering high selectivity. The surface-initiated nature of the reaction is confirmed by kinetic studies and spectroelectrochemical characterizations. This discovery adds nucleophilic oxidation to the toolbox of electrochemical organic synthesis.