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•A novel bipolar electrochemical flow microreactor.•A combination of bipolar electrochemistry and flow electrolysis techniques.•A separate electrodeposition of mixed metal ions on a ...single bipolar electrode.•A potential application in efficient recovery of valuable metals.
A combination of bipolar electrochemistry and flow electrolysis is used to develop a bipolar electrochemical flow microreactor to separately deposit mixed metal ions onto different positions of a single bipolar electrode. The potential gradient along the electrode surface was studied as a function of driving voltage, background solution concentration, solution thickness and connecting hose length. FESEM-EDX analyses indicated that both a gold-copper alloy (ca. 80 atom% Au) and bulk copper were recovered from a solution containing 0.125 mM AuCl4− and 20 mM Cu2+. This work provides a new bipolar flow microreactor for possible application in the efficient recovery of valuable metals from electronic industrial wastes.
Adsorptive‐stripping voltammetry and chronopotentiometry were used to study the adsorption and oxidation of quercetin at both graphite‐nujol paste electrode (GPE) and carbon nanotubes‐nujol paste ...electrode (CNTPE) for the potential application of carbon nanotube to flavonoids determination. As compared with GPE, CNTPE showed very great power to adsorb quercetin and resulted in a considerable signals enhancement. The adsorption isotherm of quercetin on CNTPE was of Langmuir type, and the stripping of quercetin adsorbed on CNTs showed a quasi‐reversible oxidation reaction involving two‐electron and two‐proton. The high adsorbtive activity of CNTPE was contributed to the high specific surface area and the special surface characteristics of carbon nanotubes. The peak current response of differential pulse voltammetry depended linearly on quercetin concentration. A linear equation Ip(μA)=0.987c(μmol L−1)+0.023 with a correlation coefficient of 0.994 was obtained over the concentration range 0.1–1.0 μmol L−1.
The present work reports a quercetin-modified wax-impregnated graphite electrode (Qu/WGE) prepared through an electrochemical oxidation procedure in quercetin-containing phosphate buffer solution ...(PBS), for the purpose of detecting uric acid (UA) in the presence of ascorbic acid (AA). During modification quercetin was oxidized to the corresponding quinonic structure, and in the blank buffer solution the electrodeposited film exhibits a voltammetric response anticipated for the surface-immobilized quercetin. Retarding effect of the film towards the reaction of anionic species was found; therefore the pH of sample solutions was selected to ensure the analyte in molecular form. At suitable pHs the Qu/WGE shows excellent electrocatalytic effect towards the oxidation of both AA and UA, and separates the voltammetric signal of UA from AA by about 280
mV, allowing simultaneous detection of these two species. A linear relation between the peak current and concentration was obtained for UA in the range of 1–50
μM in the presence of 0.5
mM AA, with a detection limit 1.0
μM (
S/
N
=
3). This sensor was stable, reproducible and outstanding for long-term use.
A novel poly rutin (Ru) modified paraffin-impregnated graphite electrode (WGE) was fabricated by electrochemical method. The field emission scanning electron microscope (FE-SEM), infrared spectra ...(IR), in situ UV-spectroelectrochemical and electrochemical techniques proved the immobilization of rutin on WGE. Ru undergoes electrochemical oxidation in two ways related to the two catechol hydroxyl groups and the other two hydroxyl groups; the former not only carries out a two-electron two-proton reversible reaction, but also produces unstable phenoxy radicals which readily polymerize to strongly adhere to WGE surface companying Ru monomer embeded and adsorbed in the film (Ru/WGE). The Ru/WGE displayed strong catalytic function for the oxidation of adrenalin (EP), serotonin (5-HT), and ascorbic acid (AA) and resolved the overlap voltammetric response of EP and AA into two well-defined voltammetric peaks of about 172
mV with DPV. A linear response in the range of 3.0–90.0
μM with detection limit (
s/
n
=
3) of 8.0
×
10
−7
M for EP was obtained in coexistence of AA (0.01
mM).
Electrolytic hydrogen production faces a technological issue of gas crossover through the ion-membrane between hydrogen and oxygen chambers, especially under renewable energy low power driving ...conditions. As a solution, decoupled water electrolysis was proposed and has made important progress in laboratory research but faces the problem of how to implement it in industry. The present work develops a decoupled alkaline water electrolysis system without the need to change the filter press structure of industrial electrolyzers. A wireless bipolar electrode was designed and prepared from a redox pair (NiOOH/Ni(OH)2), which functions as a substitute for conventional ion-membrane but enables complete blocking of the gas crossover (and ion transfer also) between the hydrogen and oxygen chambers. A matching control scheme was designed and implemented for continuous water electrolysis. The high purity hydrogen production achieved a coulombic efficiency of 99.2% and a specific electricity consumption of 57.5 kWh kg−1 H2 at a current density of 50 mA cm−2. This bipolar decoupling scheme of automatic operation makes an important step towards industrial implementation of decoupled water electrolysis technology.
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•A decoupled water electrolysis system based on bipolar electrode.•Decoupled in space, synchronized in time and automatic in control.•Electron transfer crossing wireless electrodes for easy industrial implementation.•Significant potential advantages for hydrogen production driven by renewables.
► Derivative cyclic voltabsorptometry (DCVA) to monitor soluble corrosion products. ► DCVA reveals potential-dependent formation and chemical transition of soluble ions. ► IP6 greatly inhibits ...pitting corrosion of copper in NaOH. ► IP6 gives different effects on the intermediate cuprous and stable cupric ions.
The ability to in situ monitor the formation and transition of soluble corrosion products generated during metal electrochemical processes is important for elucidating the corrosion mechanism. The combination of cyclic voltammetry and cyclic voltabsorptometry allows simultaneous measurements of the potential-dependent current and absorbance, the latter of which corresponds to the characteristic wavelength of each light-absorbing species. For this purpose, a long-optical-path thin-layer electrochemical cell (LTE-cell) was fabricated to study the corrosion inhibition of copper by phytate in alkaline media. A conventional electrochemical cell was also used for common cyclic voltammetry and impedance spectroscopy. The morphology of the corroded copper surfaces was characterized using field-emission scanning electron microscopy. A high corrosion inhibition efficiency (ca. 90%) of phytate on copper was achieved in 0.1moldm−3 NaOH solution. Phytate was shown to promote the formation of the soluble intermediate cuprous ions and hinder the generation of the cupric ions from pitting corrosion of the initially deposited cuprous oxide layer. The integrity of the cuprous passive layer was therefore maintained, which strongly suppressed further formation of various cupric corrosion products. The results of this study indicate that cyclic voltabsorptometry based on a LTE-cell is an effective method for studying metal corrosion processes that involve light-absorbing ions.
Developing readily scalable synthesis techniques for electrocatalysts is highly desirable for large-scale high-efficiency energy storage by water electrolysis. In this work, a coupled procedure of ...direct electrodeposition and in situ chemical transformation is presented to synthesize a nickel-iron-sulfur (Ni–Fe–S) composite catalyst. A polythiophene (PTh) coating with abundant micro/nano holes is directly deposited on graphite electrode at a constant potential. Two precursor solutions were injected onto and completely absorbed by the porous PTh coating, within which they spontaneously combine to form active species for catalysis. The PTh coating functions as a monolithic conductive matrix that well captures and disperses the catalyst species and thus decreases the contact resistance across the phase interfaces. The prepared catalyst shows a high catalytic performance for both hydrogen and oxygen evolution reactions. It requires a full cell voltage of about 2.0 V to afford a current density of 100 mA cm−2 in 1.0 M KOH, with no activity degradation at least for 24 h. The active species for the cathodic and anodic catalysis are different and discussed separately. This work indicates that in situ chemical synthesis within a porous conductive polymer coating is a promising approach for preparing high efficiency electrocatalysts.
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•Abundant micro/nano holes inside polythiophene coating working as microreactors.•Rapid formation of catalyst active species within microreactors.•Monolithic conducting matrix well capturing and dispersing active species.•A single catalyst but different active species for HER and OER catalysis.
Asymmetric conjugate addition of aryl halides or aryl triflates to electron-deficient olefins was realized by sequential Miyaura borylation and Hayashi–Miyaura conjugate addition in one pot. A ...nickel-catalyzed borylation of aryl halides or triflates and a rhodium–chiral diene complex catalyzed enantioselective conjugate addition was executed as a pair of relay reactions as a more efficient and greener protocol.
Intracerebral haemorrhage (ICH) is a common and devastating cerebrovascular disease with high morbidity and mortality, and its pathophysiological mechanisms were complex and still unclear. Increasing ...researches reported that microRNAs (miRNAs) played an important role in ICH-induced brain injury and microglial activation. In this study, we investigated the biological function of miR-590-5p and explored its molecular mechanism in ICH mice. The results of qRT-PCR showed that miR-590-5p expression level was down-regulated in perihematomal brain samples of ICH mice compared with that of sham group. In LPS-induced microglia cells, miR-590-5p level was also down-regulated at 24 h post-LPS compared with that of control group. Moreover, miR-590-5p overexpression remarkably increased the cerebral water content and neurological severity scores compared with that of scramble group in ICH mice. The production of inflammatory cytokine including IL-6, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α in ICH mice was notably inhibited by miR-590-5p overexpression. Furthermore, the results of dual-luciferase reporter assay indicated that Pellino-1 (Peli1) was a direct target of miR-590-5p. MiR-590-5p overexpression remarkably inhibited the Peli1 gene expression both mRNA and protein levels. In addition, Peli1 overexpression partly abrogated the inhibitory effect of miR-590-5p mimic. Taken together, these datas suggested that miR-590-5p attenuated brain injury in ICH mice through inhibiting Peli1 gene expression, indicating that miR-590-5p may be a promising molecular target for ICH treatment.
•Down-regulation of miR-590-5p in ICH mice and LPS-induced microglia cells.•MiR-590-5p attenuates ICH-induced brain injure.•Peli1-1 is a direct target of miR-590-5p.•Peli1 overexpression abrogates the effect of miR-590-5p mimic on ICH-induced brain injure.
Osteoporosis is characterized by an increasing osseous fragility and fracture resulting from the low mass and deteriorated microarchitecture in the bone tissue. The hormone replacement therapy and ...alendronate were frequently used to treat osteoporosis as the primary therapeutic strategy, but their adverse effects have severely limited their extensive clinical application, therefore, it is urgent to develop alternative or complementary therapeutic agents for anti-osteoporosis. Interestingly, with more people focusing on the complementary and alternative medicine, traditional Chinese herbs and formulas are being gradually recognized as safe and effective agents in the treatment of osteoporosis. In particular, a notable trend is that increasing studies are making efforts to clarify the anti-osteoporotic effects and mechanism of the tonifying kidney-yin herbs and formulas, a category of agents identified as effective therapy. Therefore, the purpose of this study is to comprehensively review the tonifying kidney-yin herbs and formulas that have been reported in the treatment of osteoporosis as well as how the agents play their roles in detail. This current study not only will advance our understanding of the actions of tonifying kidney-yin herbs and formulas, but also provide new evidence for the clinic use of the tonifying kidney-yin herbs and formulas in the treatment of osteoporosis.
