Single-compartment Cell Research Articles

Lithium-Mediated Nitrogen Reduction in a Flow Electrolyzer Cell Using Gas Diffusion Electrodes with Carbon-Based Electrocatalysts

Due to the sluggish kinetics in activating the chemically stable dinitrogen (N2) and the competing hydrogen evolution reaction in aqueous media, recent attention in the field of direct ammonia (NH3) electrosynthesis has been increasingly drawn to the lithium-mediated N2 reduction reaction (LNRR) in tetrahydrofuran (THF)-based non-aqueous electrolyte. In particular, near 100% faradaic efficiency (FE) and/or a current density (j) of 100 mA cm-2 has been demonstrated with unique electrolyte (proton-shuttle additive) and/or electrode designs (expansive electrochemical surface area) in single-compartment cells at elevated N2 pressure (5 – 20 bar).[1,2]A submerged electrode leads to electrolyte flooding and restricts to N2 mass transfer to the electrode surface where electrodeposited Li as an electron mediator is available.[3] However, flow cell electrolyzers containing gas-diffusion electrodes can improve this technology to practical relevance, which features the LNRR on the cathode and hydrogen oxidation reaction (HOR) on the anode. Differing from single-compartment cells, the HOR supplements the ethanol additive (<1 vol%) as the proton source, which not only prevents the oxidative electrolyte degradation but also reduces the energy consumption due to a lower equilibrium anode potential (E0 = 0 VRHE). Gas-diffusion electrodes (GDEs) are used in the few LNRR studies with flow cell configurations, which are prepared by electro- or electroless depositing electrocatalysts (e.g., Pt [4] or PtAu alloy [5]) onto a porous substrate.In this work, carbon-based electrocatalysts (Vulcan XC72R carbon black, battery-grade conductive carbon SUPER C45, and graphitic carbon SFG6L) as low-cost alternatives to previously studied precious metals are assessed for their LNRR performance in flow cells using an HOR anode. In comparison to Vulcan-supported Pt, XC72R and C45 can obtain similar NH3 production rates (rNH3 )and FE at the same . Continuous LNRR at -3 mA cm-2 was demonstrated with linearly increased NH3 production for over 8 h without catalyst layer detachment, which was also verified with open circuit and Ar control experiments (Fig. 1). By presenting the LNRR activity with GDEs spray-coated with carbon-based electrocatalysts, opportunities for future research are suggested, such as novel carbon materials and porous substrates other than SSC for facile N2 mass transfer and Li deposition.

The effect of water admixture on aprotic Mg-O2 battery performance

Generally, aprotic Li-O2 batteries performance is significantly influenced by water impurity in electrolyte/gas via promotion of Li2O2 mesocrystallization. In the case of promising alkali-earth metals this issue remains unexplored. Here we have studied the role of water content in DMSO-based electrolyte in discharge process of Mg-O2 cells with metallic magnesium anode and carbon cathode. We found that water impurity in the electrolyte is not a key factor determining the discharge capacity for a Mg-O2 battery, at least in a single-compartment cell. Morphology of discharge product does not change upon addition 8000 ppm of water. Discharge products contain major amount of electrolyte byproducts and negligible concentration of magnesium peroxide. Under high water content (more than 8000 ppm) Mg(OH)2 is also formed as discharge product, but content of by-products still remains high.

Membraneless unbuffered seawater electrolysis for pure hydrogen production using PtRuTiOx anode and MnOx cathode pairs

Seawater electrolysis is promising as an in situ H2 production method, allowing immediate overseas transport of the produced H2. In this study, membraneless electrolysis of undisturbed, unbuffered seawater (pH 8.2) is proposed to produce high-purity H2. A ternary Pt, Ru, and Ti (PRT) catalyst with a minimized Pt level (Pt0.06Ru0.24Ti0.7Ox) drives chloride oxidation reaction (ClOR) at a Faradaic efficiency (FE) of ∼100% in saline water at current density (J) of 800 mA cm−2 over 500 h. Chlorine reduction reaction (ClRR) is also inhibited on MnOx electrodes, leading to hydrogen evolution reaction (HER) at an FE of ∼100% even in the presence of chlorine species (HClO/ClO−). Finally, the PRT anode/MnOx cathode pair is demonstrated to drives ClOR and HER at FEs of ∼100% at J = 80 mA cm−2 over 100 h in a single-compartment cell containing seawater. Oxygen evolution reaction and ClRR are completely inhibited during seawater electrolysis.

Scale-up in PEM electro-ozonizers for the degradation of organics

• PEM electrolyzers produces important concentrations of ozone. • Comparison of three commercial electrochemical cells with different sizes. • Important differences in performance despite being based on the same mechanical concept. • Large removals of organics. This work focuses on the scale-up of electro-ozonizers by evaluating the production of ozone and the degradation of clopyralid synthetic wastes using three commercial PEM electrolyzers. The mechanical concept of the three cells is similar: a single compartment cell equipped with a MEA (consisting of a polymer exchange membrane and two pressed diamond coatings electrodes), powered with monopolar electric connection and where water flows on the surface of the electrodes, although the main electrolyte is the Nafion proton exchange membrane. However, their size and recommended operating conditions are not as similar, and their comparison becomes a good scaleup case study. The CabECO® cell consists of 2 MEAs with a total surface area of 24 cm 2 , a maximum operating current density of 2. 0A. The Mikrozom® cell consists of only one MEA with a net surface electrodic area of 112 mm 2 and a maximum operation current density of 1.0 A. Finally, the CONDIAPURE® cell consists of a single MEA with a total surface area of 146 cm 2 and a maximum operation current density of 10.0 A. The performance under mild and extreme operating conditions was compared and the results show that, although the cell concept is similar, the results obtained differ very significantly. The three PEM electrolyzers tested can produce ozone efficiently and mineralize completely clopyralid. The only intermediates measured come from the cathodic hydrodechlorination of clopyralid and oxidative intermediates were only detected at trace concentrations. CabECO® cell demonstrates an outstanding performance with very high current efficiencies in the production of ozone. However, the highest mineralization efficiencies are obtained with the Microzon®, which, although it is the PEM electrolyzer with the smallest active area, is the most efficient because can reach high ozone concentrations and achieve the best clopyralid mineralization. Efficiencies as high as 0.47 mg O 3 Wh −1 can be obtained with this cell. Slightly lower values are reached by the CabECO® cell (0.38 mg O 3 Wh −1 ). Enlarging electrode surface area does not seem to be a good strategy from the viewpoint of efficiency and it seems to promote side reactions that compete with ozone production and with the degradation of organics. This means that stacking rather than electrode enlarging should be the strategy more advisable for scaling up the electro-ozonation technology.

Rational Design of a Photosystem I Photoanode for the Fabrication of Biophotovoltaic Devices

AbstractPhotosystem I (PSI), a robust and abundant biomolecule capable of delivering high‐energy photoelectrons, has a great potential for the fabrication of light‐driven semi‐artificial bioelectrodes. Although possibilities have been explored in this regard, the true capabilities of this technology have not been achieved yet, particularly for their use as bioanodes. Here, the use of PSI Langmuir monolayers and their electrical wiring with specifically designed redox polymers is shown, ensuring an efficient mediated electron transfer as the basis for the fabrication of an advanced biophotoanode. The bioelectrode is rationally implemented and optimized for enabling the generation of substantial photocurrents of up to 17.6 µA cm−2 and is even capable of delivering photocurrents at potentials as low as −300 mV vs standard hydrogen electrode, surpassing the performance of comparable devices. To highlight the applicability of the developed light‐driven bioanode, a biophotovoltaic cell is assembled in combination with a gas‐breathing biocathode. The assembly operates in a single compartment cell and delivers considerable power outputs at large cell voltages. The implemented biophotoanode constitutes an important step toward the development of advanced biophotovoltaic devices.

Electro-oxidation of a Commercial Formulation of Glyphosate on Boron-Doped Diamond Electrodes in a Pre-pilot-Scale Single-Compartment Cell

Kinetic and environmental aspects related with the mineralization of a commercial glyphosate (GP) formulation in a pre-pilot-scale reactor were assessed. Assays were performed at an acidic pH using Na2SO4 as support electrolyte at five different current densities. GP removal can be achieved in 60 min and is not dependent on the applied current density; however, the reduction of organic carbon (TOC) and chemical oxygen demand (COD) from the sample evidence the impact of the limitations of mass transfer in aspects like energy consumption, effluent quality, and sustainability of the process. Assays at 120 and 240 mg L−1 revealed that it is feasible to improve the biodegradability of the effluent after 300 min of treatment using higher current densities (80 and 100 mA cm−2). At 360 mg L−1, neither the current density nor the time of treatment had an impact on the biodegradability of the effluent at all the assessed current densities. GP removal could have an environmental footprint (1.3 kg CO2 Eqv/kg TOC) in countries where the energy matrix depends on hydropower. In countries where electricity is generated from non-renewable raw materials, like gas or coal, the emissions of greenhouse gasses (GHG) could increase 170% and 439%, respectively. The use of renewable energy sources, like wind power or solar, could reduce the GHG emission to 0.3 kg CO2 Eqv/kg TOC. The cost of treatment ranged between US$ 0.7 and 2.1 g TOC−1 removed; this variability is due to the selected energy source and the subsidies established in each country.

Electrochemical oxidation of 2-chloroaniline in single and divided electrochemical flow cells using boron doped diamond anodes

Electrochemical oxidation (EO) using boron-doped diamond (BDD) electrodes attracted increasing interests due to its high efficiency in mineralizing chlorinated organic pollutants in water. However, it produces hazardous disinfection by-products (DBPs) including chloramines, chlorate and perchlorate ions and discharges acidic streams. In this work, an attempt to neutralize the acidic effluent and reduce the production of DBPs was developed. To do that, the EO of 2-chloroaniline (2-CA) in single and divided electrochemical flow cells using BDD anode and stainless steel cathode was investigated. The results showed that complete degradation of 2-CA and high mineralization yields were achieved using single and divided compartment cells. The separation of anolyte and catholyte by anion exchange membrane (AEM) in divided electrochemical configuration enhanced the efficiency of the electrochemical treatment and reduced the energy consumption; while, higher concentrations of free chlorine, nitrate, chlorate, and perchlorate ions were generated in the anolyte. A post-treatment of the treated solution in the cathodic compartment at low current density was effective in reducing the amount of free chlorine and chlorate ions, transferring chloride and nitrate ions to the anodic compartment by electro-dialysis, and neutralizing the anolyte and catholyte. Divided electrochemical cell configuration has the potential to achieve more efficient treatment of 2-CA for the recovery of valuable by-products (which can be considered as a powerful synthetic tool, from an environmental point of view; to produce high-added value products).

Application of a Screen-Printed Carbon Electrode Modified with Printex 6L and Deep Eutectic Solvent for Detection and Quantification of 17β-Estradiol

This work proposes the development of a screen-printed electrode (SPE) based on graphite ink as carbonaceous material and modified with a mixture of Printex 6L carbon and deep eutectic solvent (DES) (SPE-P6LCDES), used for detection and quantification of 17β-estradiol (E2) in mineral water, synthetic urine, and artificial saliva samples. The characterization of all electrodes was evaluated by Scanning Electron Microscopy (SEM), Fourier transform infrared (FTIR) and Electrochemical Impedance Spectroscopy (EIS). Electrochemical measurements were performed in a system composed of a single compartment cell (100.0 mL), containing a reference electrode (Ag/AgCl/KClsat), Pt wire as a counter electrode and SPE as a working electrode. Electrochemical studies of E2 were performed in 0.1 mol L-1 phosphate buffer solution (PBS) at pH 7.0 by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). These studies evaluate the electroactivity of SPE-P6LCDES for E2, showing oxidative signals close to +0.98 V. The linear ranges of E2 concentrations studied were 0.00732 – 0.417 μmol L -1 for unmodified SPE and 0.00090 – 0.21 μmol L-1 for the SPE-P6LCDES, presenting limit of detection (LOD) of 0.177 μmol L-1 and 0.0065 μmol L -1, respectively. The use of DES + Printex 6L carbon as a modifier in the unmodified SPE allowed for strong intramolecular interactions between DES and the E2 molecule, which increased the intensity of the current responses because it is a sensor with greater sensibility, sensitivity, and reproducibility. The results obtained from the E2 recovery study on real samples were between 92.15% and 102.10%. By the method validation study (UV-Vis spectroscopy), the studied E2 concentrations of 10 and 60 μmol L-1 demonstrated recovery of +99.16% (+ 1.4%) and +100.16% (+1.9%), respectively.

Carbochlorination of Cobalt Oxide and Electrochemical Recovery of Co in an Amide-Type Ionic Liquid

Recycle of rare metals from electric devices is demanded from the viewpoints of production costs and environmental protection. Carbochlorination is a traditional pyrometallurgical process to convert metal oxides in metal waste into metal chlorides. However, high temperature is often required for the carbochlorination process, leading to an increase in the recycling cost. We have already reported that the dissolution of palladium oxide was possible in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing BMPCl by carbochlorination at a relatively lower temperature. In the present study, the carbochlorination of cobalt oxide (CoO) was investigated in BMPTFSA containing BMPCl. Recovery of Co was also attempted by electrochemical reduction of the cobalt species in the ionic liquid.CoO was reacted with some carbochlorination reagents in 0.5 M BMPCl/BMPTFSA in a perfluoroethylene propylene copolymer (FEP) tube at 150 °C for 24 h. The residual carbochlorination reagents and byproducts were removed by heating under vacuum at 100 - 150 °C for 24 h. The electrochemical measurements were conducted using a single-compartment cell using glassy carbon as a working electrode, cobalt as a counter electrode, and silver wire immersed in 0.1 M AgCF3SO3/BMPTFSA isolated from the sample electrolyte with porous glass as the reference electrode.CoO was insoluble in 0.5 M BMPCl/BMPTFSA without the carbochlorination reagents. CoO was found to be dissolved as [CoCl4]2– in 0.5 BMPCl/BMPTFSA in the presence of the carbochlorination reagents at 150 °C by the ultraviolet-visible spectroscopy. A cathodic current peak assignable to the reduction of [CoCl4]2– was observed at -3.1 V in the cyclic voltammogram of a GC electrode in the ionic liquid after carbochlorination of CoO. The deposits containing Co were obtained by the potentiostatic cathodic reduction in the ionic liquid, suggesting the recovery of Co from CoO is possible electrochemically with carbochlorination at low temperature.

Electro- and photo-electrooxidation of 2,4,5-trichlorophenoxiacetic acid (2,4,5-T) in aqueous media with PbO2, Sb-doped SnO2, BDD and TiO2-NTs anodes: A comparative study

Abstract In this work, the 2,4,5-T degradation in aqueous media was studied by electro- (EC) and photoelectrochemical (PEC) oxidation methods, which are two of the most important advanced oxidation processes (AOPs) for wastewater treatment. Both EC and PEC experiments were carried out in a single compartment cell under galvanostatic conditions (30 mA cm−2) at 298 K by using 0.05 M Na2SO4 + 200 ppm 2,4,5-T at pH 3 and pH 9, as model solutions. EC oxidation was performed using Sb-doped SnO2, PbO2 and boron doped diamond (BDD) as anodic materials. Besides these anodes, TiO2 in a nanotubular structure (TiO2 NTs) with or without PbO2 dispersed nanoparticles (TiO2::PbO2) were also used for PEC oxidation process. In all cases, the electrolyzed solutions were periodically analyzed by UV–vis spectrophotometry (232 or 235 nm) and liquid chromatography (HPLC) for 2,4,5-T as well as the oxidation by-products. The mineralization level was occasionally measured by using total organic carbon (TOC). For PEC experiments the photocurrent response variations with potential in 0.5 M H2SO4 were obtained by the linear scanning voltammetry (LSV) method at a slow potential sweep (5 mV s−1). Results clearly showed that at 30 mA cm−2, the 2,4,5-T was 100% oxidized on Sb-doped SnO2 and 95% on PbO2 after 120 min of electrolysis, which allow to assume the EC as an adequate treatment method to remove this herbicide from wastewaters. HPLC results showed the formation of aromatic intermediates such as 2,4,5-trichlorophenol (2,4,5-TCP) and 2,5-dihydroxyquinone (2,5-DHQ) followed by the formation of carboxylic acid such as hydroxyacetic acid. For these cases, alkaline media (pH 9) was better than acidic media (pH 3) in about one magnitude order in the apparent rate constant (k). On the other hand, photochemical activity results showed that PEC on TiO2-NTs::PbO2 had higher photocurrent density values than on naked TiO2 NTs as photoanodes. These electrodes also had the better photo conversion efficiencies (η), which strongly suggests the occurrence of a “co-catalysis” effect due to an electronic transfer assisted by the closed contact between TiO2 and PbO2. This fact was supported by the PEC oxidation of 2,4,5-T in aqueous solution, whose k value was slightly lower than that observed for bulk material.

Visible-light triggered self-breathing-like dual-photoelectrode internal-driven self-powered sensor: Metal–ligand charge transfer (MLCT) induced signal-off strategy for the microcystin-LR assay

Developing new self-powered sensors is highly demanded for smart portable electronic devices. Herein, a novel visible-light-driven self-powdered aptasensor with a metal-ligand charge transfer (MLCT)-induced signal-off strategy was established for microcystin-LR (MC-LR) sensing. The aptasensor was based on a self-breathing-like dual photoelectrode photocatalytic fuel cell (PFC) that was assembled with visible-light responsive ternary NG-TiO2-Ag and NG-BiOBr nanocomposites as photoelectrodes. The device did not require aeration or a membrane in a single-compartment cell. The self-powdered PFC system exhibited a greater power output than previously-reported ones that used only TiO2. The photo-triggered self-bias between the photoelectrodes generated electron transfer and a power output in the external circuit. A self-powered aptasensor for MC-LR was constructed using an MC-LR-binding aptamer as the recognition element. The results showed an unexpected sequential decrease in power output, followed by the capture of MC-LR, which is different from earlier signal-on strategies. The inhibited output of the PFC after MC-LR capture was controlled by an MLCT-induced signal-off mechanism, which was confirmed by the UV–Vis absorption and fluorescence emission spectra. Furthermore, the power output of the self-powdered sensor depended on the MC-LR concentration. When used for ultrasensitive trace MC-LR detection, the self-powdered sensor showed a linear relationship from 1 pM to 316 nM and a detection limit of 0.33 pM. This work provides theoretical guidance for sensing strategies using self-powdered sensors and offers a rational device design for cost-effective electricity generation from renewable resources.

Effect of plasma power on the semiconducting behavior of low-frequency PECVD TiO2 and nitrogen-doped TiO2 anodic thin coatings: photo-electrochemical studies in a single compartment cell for hydrogen generation by solar water splitting

Previously optimized anatase and nitrogen-doped anatase TiO2 coatings have been grown by low-frequency plasma-enhanced chemical vapor deposition (PECVD) on different kinds of substrates at low plasma power (64 W) and high plasma power (100 W) for photo-electrochemical studies. Nitrogen-doped TiO2 layers exhibit better photoactivity and also higher electronic conductivity under UV and visible irradiations than non-doped materials. The main reason is that nitrogen introduction induces TiO2 band gap tailoring towards higher wavelengths. In addition, films prepared at low plasma power present a ‘typical photo-material’ behavior (whose activity depends directly on the presence of light) while layers synthesized at higher plasma power contain an initial conductive phase giving them an activity that exists in the dark yet and can be slightly enhanced by illumination. Such conclusions are prominent in the field of photo-anodic thin films; indeed PECVD could constitute a promising approach for tailoring the efficiency of photo-electrochemical cells for hydrogen production under solar light.

Studies of Cobalt(III) and Chromium(III) Complexes as Mediators in the Silver Nanoparticle Electrosynthesis in Aqueous Media

Metal complexes [Cr(bipy)3]3+, [Co(bipy)3]3+, and [Co(sep)]3+ in aqueous media at the potentials of M(III)/M(II) redox couple are shown playing a role of mediators in the electrosynthesis of silver nanoparticles, stabilized in a polyvinylpyrrolidone shell, by means of Ag(I) reduction. [Cr(bipy)3]3+ is consumed under the conditions of long-term preparative electrolysis, the reduction process is accompanied by cathode passivation, therefore, the Ag+ ions complete conversion to the Ag-nanoparticles is unattainable. The two other metal complexes are fully remained unimpaired; the mediated electrosynthesis of the Ag-nanoparticles is carried out well effectively: the Ag-nanoparticles are produced in the solution bulk with a nearly quantitative yield, a theoretical charge being consumed. the [Co(bipy)3]3+-mediated reduction of the Ag+ ions, generated by a silver anode in situ dissolution in the course of single compartment cell electrolysis, is accompanied by the anode metal dispersion and results in the formation of polydisperse Ag-nanoparticles. The summary Ag-nanoparticle current efficiency in the solution bulk comes to 128%. Thus formed Ag-nanoparticles are characterized by using dynamic light scattering, scanning and transmission electron microscopy, and X-ray powder diffraction. The Ag-nanoparticles are spherical, with a mean size of 83 ± 53 nm, or have a form of nanowires, with a length of l = 1216 ± 664 nm and diameter of d = 94 ± 17 nm. The [Co(sep)]3+-mediated AgCl reduction gives ellipsoidal Ag-nanoparticles sized l = 46 ± 19 nm, d = 27 ± 7 nm; the silver crystallite mean size is 20(1)–34.4(9) nm.

Efficient photoelectrochemical oxidation of rhodamine B on metal electrodes without photocatalyst or supporting electrolyte

We designed photoelectrochemical cells to achieve efficient oxidation of rhodamine B (RhB) without the need for photocatalyst or supporting electrolyte. RhB, the metal anode/cathode, and O2 formed an energy-relay structure, enabling the efficient formation of O 2 – species under ultraviolet illumination. In a single-compartment cell (S cell) containing a titanium (Ti) anode, Ti cathode, and 10 mg·mL–1 RhB in water, the zero-order rate constant of the photoelectrochemical oxidation (kPEC) of RhB was 0.049 mg·L–1·min–1, while those of the photochemical and electrochemical oxidations of RhB were nearly zero. kPEC remained almost the same when 0.5 mol·L–1 Na2SO4 was included in the reactive solution, regardless of the increase in the photocurrent of the S cell. The kPEC of the illuminated anode compartment in the two-compartment cell, including a Ti anode, Ti cathode, and 10 mg·mL–1 RhB in water, was higher than that of the S cell. These results support a simple, eco-friendly, and energysaving method to realize the efficient degradation of RhB. Open image in new window

Fullerene Mediated Electrosynthesis of Silver Nanoparticles in Toluene-DMF

Using C60 and C70 fullerenes as mediators, efficient mediated electrosynthesis of silver nanoparticles (AgNP) in toluene-DMF/ 0.1 M Bu4NBF4 medium was carried out by reduction of Ag+ at the potentials of the fullerene radical anions generation. Synthesis was performed in the absence and in the presence of poly(N-vinylpyrrolidone) (PVP) in the cathodic compartment of a diaphragm-separated cell by addition of Ag+ as AgNO3 into solution and in a single compartment cell by in situ generation of Ag+ by dissolution of an Ag-anode during electrolysis. In all cases, Ag+ ions are quantitatively reduced upon consumption of the theoretical amount of electricity; the generated metal is quantitatively obtained in solution bulk in the form of spherical NP with sizes in the range from 11 ± 2 to 24 ± 9 nm. In electrolysis in a single compartment cell, dispersion of the Ag-anode occurs along with its dissolution and the total current efficiency of AgNP is 131 ÷ 163%. In the presence of PVP, individual AgNP are stabilized in the PVP shell. The isolated Ag/PVP nanocomposite is deposited on a solid support both in individual form and as three-component Ag/PVP/fullerene nanocomposite. In the absence of PVP, the Ag/fullerene nanocomposite is obtained.

An advanced electro-Fenton degradation system with triboelectric nanogenerator as electric supply and biomass-derived carbon materials as cathode catalyst

On the basis of the advantages of electro-Fenton (EF) and the flexible design of triboelectric nanogenerator (TENG) and biomass carbon materials, a self-powered EF system is conceived, which is self-driven by a flexible multilayered TENG (FM-TENG) using carbon materials derived from long bean as the cathode catalyst for oxygen reduction. The synthesized carbon material is promising electrocatalyst due to its macro-/meso-porous structure, large surface area (2270m2g−1), high nitrogen content and superhydrophilicity, which can facilitate dissolved O2 mass transfer and promote the oxygen reduction. The instantaneous short-circuit current, transferred charge and open-circuit voltage of FM-TENG could reach 650μA, 1.7μC and 750V, respectively, corresponding to an instantaneous power density of 2.6Wm−2 (500kΩ). Driven by FM-TENG, 4-dimethylaminoazobenzene can be decomposed to CO2 and inorganic ions by hydroxyl radical (•OH) generated via EF process. Cyclic voltammogram, gas chromatograph-mass spectrometer, UV–vis spectra and the H2O2 measurement together disclose such degradation mechanism in single-compartment cell (S-cell) and double-compartment cell (D-cell). Here, S-cell is preferable owing to the high efficiency, simple setup and low voltage. This provides a proof-of-concept of an innovative EF process using biomass-derived carbon materials as oxygen reduction electrocatalyst and FM-TENG as the electric supply to power the degradation of organic pollutants.

Unlocking the Electrocatalytic Activity of Antimony for CO2 Reduction by Two-Dimensional Engineering of the Bulk Material.

Two-dimensional (2D) materials are known to be useful in catalysis. Engineering 3D bulk materials into the 2D form can enhance the exposure of the active edge sites, which are believed to be the origin of the high catalytic activity. Reported herein is the production of 2D "few-layer" antimony (Sb) nanosheets by cathodic exfoliation. Application of this 2D engineering method turns Sb, an inactive material for CO2 reduction in its bulk form, into an active 2D electrocatalyst for reduction of CO2 to formate with high efficiency. The high activity is attributed to the exposure of a large number of catalytically active edge sites. Moreover, this cathodic exfoliation process can be coupled with the anodic exfoliation of graphite in a single-compartment cell for in situ production of a few-layer Sb nanosheets and graphene composite. The observed increased activity of this composite is attributed to the strong electronic interaction between graphene and Sb.

Electrosynthesis of gold nanoparticles mediated by methylviologen using a gold anode in single compartment cell

Methylviologen mediated reduction of Au i ions generated in situ by dissolution of a gold anode in single compartment cell has been used for the electrosynthesis of spherical gold nanoparticles (Au-NPs) stabilized by poly(N-vinylpyrrolidone). The size of Au-NPs was from 15±6 to 27±9 nm, depending on the electrosynthesis conditions. Au-NPs were characterized by cyclic voltammetry, UV-VIS spectroscopy, dynamic light scattering, scanning and transmission electron microscopy.

Electrosynthesis of boronic acids and esters

Electrochemical methodology offers an interesting alternative to the classical synthesis of organoboronic derivatives. A series of aryl- allyl- and benzylboronic acids and esters has been prepared via an electrosynthesis methodology, which uses a single compartment cell fitted with a metal anode, in the absence of catalysts and under mild conditions.

Self-Powered Electrochemical Oxidation of 4-Aminoazobenzene Driven by a Triboelectric Nanogenerator.

A rotary disc-structured triboelectric nanogenerator (rd-TENG) on the basis of free-standing electrification has been designed, where the aluminum composite panel has not been tailored to the stator becauseit is commercially available and cost-effective, has good electronic conductivity, and is easily processed. With the rotating speed increasing from 200 to 1000 rpm, the short-circuit current (Isc) is sharply enhanced from 50 μA to 200 μA, while the measured open-circuit voltage (Voc) and transferred charge (Qtr) almost keep constant, 600 V and 0.4 μC, respectively. The matched load for the rd-TENG at a rotating speed of 600 rpm is 2.7 MΩ, generating a maximum power of 19.75 mW, which corresponds to a maximum power density of 2.28 W m-2. Using the electric power generated by such a rd-TENG, highly toxic and carcinogenic 4-aminoazobenzene can be selectively treated to produce CO2 or an oligomer via reasonably controlling electrochemical oxidation potentials. The underlying mechanism is tentatively proposed based on the cyclic voltammogram, gas chromatograph-mass spectrometer, electrochemical impedance spectroscopy, and UV-vis spectra. Here the electrochemical degradation in a single-compartment cell is more valid, preferable, and feasible. The output Voc and rectified current of rd-TENG guarantee its extensive application to self-power electrochemical degradation of other azo compounds, i.e., 2-(4-dimethylaminophenylazo) benzoic acid, to CO2. This work suggests that rd-TENG, sustainable energy, can be feasibly designed to self-power a practical electrochemical treatment of dyeing wastewater by harvesting vibration energy.