Electrochemical synthesis of trimetallic nickel-iron-copper nanoparticles via potential-cycling for high current density anion exchange membrane water-splitting applications

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels.Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen.Nevertheless,electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods,such as sol-gel,hydrothermal,or surfactantassisted approaches,which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination.Therefore,this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam.The synthesized material exhibited remarkable performance,requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm^(-2)current density in alkaline solution.Furthermore,this material was integrated into an anion exchange membrane watersplitting device and achieved an exceptionally high current density of 1 A cm^(-2)at a low cell voltage of2.13 V,outperforming the noble-metal benchmark(2.51 V).Additionally,ex situ characterizations were employed to detect transformations in the active sites during the catalytic process,revealing the structural transformations and providing inspiration for further design of electrocatalysts.

Effects of alkaline cations (M^+= Li^+, Na^+, K^+, Cs^+) on the electrochemical synthesis of polyaniline in nitric acid electrolyte

The effects of alkaline cations （M^＋ = Li^＋, Na^＋, K^＋, Cs^＋）on the electrochemical synthesis of polyaniline were carfled out under cyclovoltammetric conditions using nitrates of Li^＋, Na^＋, K^＋, and Cs^＋ as the supporting electrolytes. The results show that the oxidation potentials of aniline in the electrolytes decrease as the protonation extent of aniline decreases from the fast scan, which is caused by the decrease of the ionic radius of alkaline metal ions at the same concentration of alkaline cations. With the scan number increasing, the deposit charge Q as the characteristic growth function also depends on the protonation of aniline, and it increases with the ionic radius of alkaline cations increasing. SEM images show the effect of alkaline cations on the morphology of polyaniline. It is clear that the ionic mobility of alkaline cations is further lower than that of W. Alkaline cations and counter-ions were the species responsible for the enhancement of Pani electrosynthesis. Therefore, this is exactly what SEM images show： a relatively rough fibrous structure in the case of Pani-H^＋ suggesting a sponge-like structure and a highly orderly fiber-like structure in the case of Pani-M^＋.

Electrochemical Synthesis of Polythiophene in an Ionic Liquid

Polythiophene (PTh) was prepared by the direct electrochemical synthesis in an ionic liquid ([BMIM]PF6) containing 0.1 mol/L thiophene by cyclic voltammetry, constant potential and constant current techniques. It is found that smooth and bluegreen PTh films can be obtained at a potential of ca. +1.75 V ( vs. Ag/AgCl ) or a current of ca. 1.5 mA cm-2 in the ionic liquid.

Defect engineering of single-walled carbon nanohorns for stable electrochemical synthesis of hydrogen peroxide with high selectivity in neutral electrolytes

Hydrogen peroxide(H_(2)O_(2))is one of the most important chemicals,which are commonly used in the paper and pulp industry,water purification and environmental protection[1-3].Most of the commercial available H_(2)O_(2) is produced by the anthraquinone oxidation process,which is environment unfriendly.

Electrochemical synthesis of alkali-intercalated iron selenide superconductors

Electrochemical method has been used to insert K/Na into FeSe lattice to prepare alkali-intercalated iron selenides at room temperature. Magnetization measurement reveals that KxFe2Se2 and NaxFe2Se2 are superconductive at 31 K and 46 K, respectively. This is the first successful report of obtaining metal-intercalated FeSe-based high-temperature superconductors using electrochemical method. It provides an effective route to synthesize metal-intercalated layered compounds for new superconductor exploration.

Overview of emerging catalytic materials for electrochemical green ammonia synthesis and process

The concept of“green-ammonia-zero-carbon emission”is an emerging research topic in the global community and many countries driving toward decarbonizing a diversity of applications dependent on fossil fuels.In light of this,electrochemical nitrogen reduction reaction(ENRR)received great attention at ambient conditions.The low efficiency(%)and ammonia(NH_(3))production rates are two major challenges in making a sustainable future.Besides,hydrogen evolution reaction is another crucial factor for realizing this NH_(3)synthesis to meet the large-scale commercial demand.Herein,the(i)importance of NH_(3)as an energy carrier for the next future,(ii)discussion with ENRR theory and the fundamental mechanism,(iii)device configuration and types of electrolytic systems for NH_(3)synthesis including key metrics,(iv)then moving into rising electrocatalysts for ENRR such as single-atom catalysts(SACs),MXenes,and metal–organic frameworks that were scientifically summarized,and(v)finally,the current technical contests and future perceptions are discussed.Hence,this review aims to give insightful direction and a fresh motivation toward ENRR and the development of advanced electrocatalysts in terms of cost,efficiency,and technologically large scale for the synthesis of green NH_(3).

Facile electrochemical synthesis of nano iron porous coordination polymer using scrap iron for simultaneous and cost-effective removal of organic and inorganic arsenic

Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure salts, and only application for the removal of inorganic arsenic. In this work, we developed an eco-economic and facile electrochemical method to synthesize iron porous coordination polymers （FePCPs） for the simultaneous removal of inorganic and organic arsenic from natural water.

Electrochemical synthesis and characterization of polydiphenylamine

Electrochemical oxidation of diphenylamine(DPA)in acetonitrile solution produced an adhesive conducting polydiphenylamine(PDPA)film on the electrode,which exhibited multiple colour variation in a wide range of potential.The polymer was characterized by cyclic voltam- merry,FTIR and ESR.The results indicate that the electropolymerization of diphenylamine per- forms via the 4,4＇C—C phenyl-phenyl coupling mechanism.FTIR,ESR and conductivity mea- surements for the different states of PDPA show that polydiphenylamine can be reversibly doped and dedoped either chemically or electrochemically.It is evidenced also that there are paramagnetic species—polarons in PDPA supposed to be the current carrier.

Hydrothermal Synthesis, Crystal Structure, Spectrum and Electrochemical Analysis of the Copper(Ⅱ) Coordination Polymer

The three-dimensional framework copper（Ⅱ） coordination polymer with basic copper carbonate and 3-（pyridin-2-yl）-1,2,4-triazole has been hydrothermally synthesized. It crystallizes in monoclinic space group P21/c, with a = 1.20860（3）, b = 1.29581（2）, c = 1.67863（3） nm, β = 116.0280（2）°, C21H12Cu3N12, Mr = 623.05, V = 2.36230（9） nm3, Dc = 1.752 g/cm3, Z = 4, F（000） = 1236, GOOF = 1.037, the final R = 0.0408 and wR = 0.1141. Every unit cell contains three copper atoms and three 3-（pyridin-2-yl）-1,2,4-triazole ligands. Every central Cu（Ⅱ） ion is coordinated by four nitrogen atoms of the 3-（pyridin-2-yl）-1,2,4-triazole ligands, forming a distorted tetrahedron. The title complex exhibits an intense photoluminescence at room temperature with the maximum emission at 392 nm. The cyclic voltametric behavior of the complex shows that the electron transfer in electrolysis reaction is irreversible.

Preparation of nanometer γ-Fe_2O_3 by electrochemical oxidation in non-aqueous medium

The preparation of nanometer γ-Fe2O3 through an electrochemical process was studied at room temperature, using a metal iron plate as sacrificing anode and a sheet of stainless steel as cathode, in non-aqueous mediate containing （Bu）4 NBr as support electrolyre and 2% （vol%） water. The powdery particles obtained were then calcined at 300 ℃. The products were characterized by IR, XRD, SEM, TEM and laser particle size analyser, indicating the fine particle is a pure nanometer γ-Fe2O3. The morphology is like coneshaped and their average size is 22.0 nm. Furthermore the VSM spectrum shows that the particle＇s coercivity （3.9 × 10^3 A/m） is rather small, presenting the excellent super-paramagnetism.

Strategies for Sustainable Production of Hydrogen Peroxide via Oxygen Reduction Reaction:From Catalyst Design to Device Setup

An environmentally benign,sustainable,and cost-effective supply of H_(2)O_(2)as a rapidly expanding consumption raw material is highly desired for chemical industries,medical treatment,and household disinfection.The electrocatalytic production route via electrochemical oxygen reduction reaction(ORR)offers a sustainable avenue for the onsite production of H_(2)O_(2)from O2 and H2O.The most crucial and innovative part of such technology lies in the availability of suitable electrocatalysts that promote two-electron(2e^(–))ORR.In recent years,tremendous progress has been achieved in designing efficient,robust,and cost-effective catalyst materials,including noble metals and their alloys,metalfree carbon-based materials,single-atom catalysts,and molecular catalysts.Meanwhile,innovative cell designs have significantly advanced electrochemical applications at the industrial level.This review summarizes fundamental basics and recent advances in H_(2)O_(2)production via 2e^(–)-ORR,including catalyst design,mechanistic explorations,theoretical computations,experimental evaluations,and electrochemical cell designs.Perspectives on addressing remaining challenges are also presented with an emphasis on the large-scale synthesis of H_(2)O_(2)via the electrochemical route.

Recent Advances of Electrocatalyst and Cell Design for Hydrogen Peroxide Production

Electrochemical synthesis of H_(2)O_(2) via a selective two-electron oxygen reduction reaction has emerged as an attractive alternative to the current energy-consuming anthraquinone process. Herein, the progress on electrocatalysts for H_(2)O_(2) generation, including noble metal, transition metalbased, and carbon-based materials, is summarized. At first, the design strategies employed to obtain electrocatalysts with high electroactivity and high selectivity are highlighted. Then, the critical roles of the geometry of the electrodes and the type of reactor in striking a balance to boost the H_(2)O_(2) selectivity and reaction rate are systematically discussed. After that, a potential strategy to combine the complementary properties of the catalysts and the reactor for optimal selectivity and overall yield is illustrated. Finally, the remaining challenges and promising opportunities for highefficient H_(2)O_(2) electrochemical production are highlighted for future studies.

Recent advances and challenges of nitrogen/nitrate electro catalytic reduction to ammonia synthesis

The Haber-Bosch process is the most widely used synthetic ammonia technology at present.Since its invention,it has provided an important guarantee for global food security.However,the traditional Haber-Bosch ammonia synthesis process consumes a lot of energy and causes serious environmental pollution.Under the serious pressure of energy and environment,a green,clean,and sustainable ammonia synthesis route is urgently needed.Electrochemical synthesis of ammonia is a green and mild new method for preparing ammonia,which can directly convert nitrogen or nitrate into ammonia using electricity driven by solar,wind,or water energy,without greenhouse gas and toxic gas emissions.Herein,the basic mechanism of the nitrogen reduction reaction(NRR)to ammonia and nitrate reduction reaction(NO_(3)^(-))to ammonia were discussed.The representative approaches and major technologies,such as lithium mediated electrolysis and solid oxide electrolysis cell(SOEC)electrolysis for NRR,high activity catalyst and advanced electrochemical device fabrication for(NO_(3)^(-))RR and electrochemical ammonia synthesis were summarized.Based on the above discussion and analysis,the main challenges and development directions for electrochemical ammonia synthesis were further proposed.

A facile and one-pot electrochemical method for the synthesis of a new anthraquinonethioether

The reaction of electrochemically generated anthradiquinone as a Michael acceptor with 2-mercaptobenzothiazole and 2- mercaptobenzoxazole,as nucleophiles in ethanol/water mixtures has been studied by means of cyclic voltammetry.Our voltammetric data indicate that produced anthradiquinone participates in Michael addition reaction with nucleophiles and via an ECEC mechanism converts to the new anthraquinonethioether derivatives.Based on an EC mechanism,the observed homogeneous rate constant of the Michael reaction of anthradiquinone with nucleophiles were estimated by comparing the experimental cyclic voltammograms with the digital simulated results.

Electrochemical top-down synthesis of C-supported Pt nanoparticles with controllable shape and size:Mechanistic insights and application

In this work,we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes(in the range from-2 to-10 nm).Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures,such as disks or wires.Without using any surfactants,the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential,frequency and electrolyte composition.For instance,application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles;whereas higher frequencies lead to predominantly spherical nanoparticles.On the other hand,the amplitude of the,sinusoidal signal was found to affect the particle size;the lower the amplitude of the applied AC signal,the smaller the resulting particle size.Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is-2 times higher than the state-of-the-art commercial Pt/C catalyst(0.42 A/mg)from Tanaka.In addition to this,we discussed the mechanistic insights about the nanoparticle formation pathways.

A facile electrochemical method for the synthesis of new sulfonamide derivatives of potential biological significance

The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-l,4-dione （1） in the presence of arylsulfinic acids （2a and 2b） as nucleophiles. The results show that, the electrogenerated phthalazine-l,4-dione （lox） participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.

Electrochemical Oxidative [4+2] Annulation of Different Styrenes toward the Synthesis of 1,2-Dihydronaphthalenes

A[4+2]annulation of two different styrenes to construct polysubstituted 1,2-dihydronaphthalenes was achieved.This transformation proceeded smoothly under electrochemical oxidative conditions without metal catalysts and external oxidants.A series of polysubstituted 1,2-dihydronaphthalenes were obtained with high regioselectivity and diastereoselectivity.Moreover,polysubstituted 1,2-dihydronaphthalenes were further transformed to polysubstituted 1,2,3,4-tetrahydronaphthalenes and polysubstituted naphthalenes,which show great potential in synthetic applications.

Electrochemically mediated decarboxylative acylation of N-nitrosoanilines with α-oxocarboxylic acids

An efficient palladium-catalyzed electrooxidation C–H acylation reaction of N-nitrosoanilines with α-oxocarboxylic acids was developed. The anodic oxidation of the Pd(Ⅱ) intermediate was found to be the key to complete the reaction. In this case, the N-nitroso group was observed to be an effective directing group for C–H activation reaction. Moreover, the synthetic transformation of derivatives of natural products(L-menthol, dehydroepiandrosterone, and pregnenolone) was successfully realized. Finally, flow electrochemical synthesis of some substrates was achieved.

Interfacial Synthesis ofδ-MnO2 Nano-sheets with a Large Surface Area and Their Application in Electrochemical Capacitors

Birnessite-type MnO2 （δ-MnO2） nano-sheets were successfully synthesized by an interracial synthesis method in this work. The properties and electrochemical performance of the as-prepared δ-MnO2 were analyzed and evaluated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, nitrogen adsorption measurement and electrochemical tests. This facile synthesis method enables δ-MnO2 nanosheets to show a large specific surface area （257.5 m^2 g^-1）. The electrochemical test results show that the specific capacitance is 272 F g^-1 and the specific capacitance retention is over 96.7% after 1000 cycles at a scan rate of 10 mV s^-1. All results demonstrate that δ-MnO2 has a great potential application in high- performance electrochemical capacitors, and this interracial synthesis method will be a very promising method to synthesize highly active MnO2 materials in a large scale.