Think zinc: An ideal aqueous energy storage device, referred to as a zinc ion battery, is presented. The device is characterized by high capacity, fast charge/discharge capability, safety, and ...environmental friendliness. It is composed of an α‐MnO2 cathode, a zinc anode, and a mild ZnSO4 or Zn(NO3)2 aqueous electrolyte (see scheme). The battery chemistry is based on the migration of Zn2+ ions between cathode and anode.
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•Different concentration of Gd doped Fe-Co thin films were successively deposited on Cu using electrodeposition method.•Gd-concentration of 0.05 M showed excellent magnetic ...behaviour.•Electrode prepared by 0.05 M sample exhibited enhanced water splitting performance under external applied magnetic field.
We investigated the magnetic characteristics of Gadolinium-doped Iron-Cobalt/Copper (Gd-Fe-Co/Cu) electrodeposited thin films at various Gd concentrations over 20 min at room temperature and pH 3. The structure and composition of metal ions are confirmed by X-ray diffraction and the EDAX spectrum. SEM examination of the microstructures revealed a variety of morphologies, including spherical ball-like crystallites and one-dimensional spike-like crystallites. The varied Gd ion concentrations had an effect on the Gd-Fe-Co/Cu thin films, which exhibited soft magnetic properties. The introduction of Gd3+ into the system has demonstrated ferromagnetic properties at room temperature, as verified through VSM analysis. Elevating the Gd concentration in the thin film led to an augmentation in saturation magnetization and a reduction in coercivity. Selected samples were subjected to BET and CV studies. CV studies confirmed the capacitive behaviours of the sample. The best magnetic behaviour was seen for the Gd concentration of 0.05 M, suggesting that these films might be suitable candidates for application in energy storage and conversion. Further, the best sample was taken for water splitting studies and showcased excellent HER performance under magnetic field.
A three-dimensional g-C3N4/MWNTs/GO hybrid modified electrode was constructed as an electrochemical sensor for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). ...Due to the high conductivity of MWCNTs and the strong synergy between g-C3N4 and GO, the combination of the three effectively improved the electrocatalytic activity of the modified electrode for the oxidation of AA, DA, and UA, and solved the problems such as overlapping anodic peaks. The electrochemical performance of the as-constructed sensor was investigated and optimized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linear response range of AA, DA, and UA in the optimal condition was 0.2–7.5 mM, 2–100 μM, and 4–200 μM, respectively. The detection limits (S/N = 3) of AA, DA, and UA were 96, 0.22, and 1.36 μM, respectively. The recoveries of AA, DA and UA in serum samples from three groups were 92.82–106.50%, and the relative standard deviations were less than 2%. The results show that the as-constructed g-C3N4/MWNTs/GO modified electrode has the advantages of simplicity, high sensitivity and good selectivity, and can simultaneously determine AA, DA, and UA.
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•A three-dimensional g-C3N4/MWNTs/GO hybrid electrode was constructed as an electrochemical sensor.•g-C3N4/MWNTs/GO hybrid sensor can simultaneously determine DA, AA, and UA.•The recoveries of DA, AA and UA in serum samples from three groups were 92.82–106.50%.•g-C3N4/MWNTs/GO hybrid sensor has the advantages of simplicity, high sensitivity and good selectivity.
In order to help develop robust and deployable molecular electrocatalysts for the reduction of CO2 to CO, we must understand the effects of tuning their structure and catalytic conditions. To this ...end, we quantify how modifications to the catalyst fac-Re(4,4′-R-bpy)(CO)3X (bpy = 2,2′-bipyridine, R = OCH3, CH3, tBu, H, CN, CF3; X = Cl, Br, py(OTf), or CH3CN(OTf)) with and without an added proton source (phenol, acetic acid, 2,2,2-trifluoroethanol) affect the catalyst stability, activity, and overpotential. Through cyclic voltammetry experiments, we found that the substituents and proton source had a large effect on both overpotential and activity. Substituents with moderate electron-donating ability (tBu and CH3) increased activity and overpotential in comparison to the unsubstituted complex Re(bpy)(CO)3Cl. In contrast, substituents resulting in too much electron density distributed over the bpy ligand, either from too-strong electron-donating ability (OCH3) or from the requirement of a third reduction to activate the complex (CN and CF3), destabilized the catalyst. An added proton source both increased the activity and decreased the overpotential by 200 mV for all catalyst derivatives, shifting the catalytic mechanism from an electron-first pathway to a proton-first pathway. We used binding energies calculated via density functional theory to help understand the substituent effect on the catalyst affinity for CO2 and other intermediates relevant to the catalytic mechanism. Catalyst activity was quantified using intrinsic rate constants determined through the utilization of catalytic plateau currents, as well as the application of a foot of the wave analysis, which yielded incongruent values. Of those complexes tested, Re(4,4′-tBu-bpy)(CO)3Cl with an added 1 M phenol yielded the most active catalytic system (k cat = 6206 s–1) at an overpotential of 0.67 V.
•17β-estradiol has been shown to increase dopamine release in the dorsal striatum.•It is not known if 17β-estradiol affects tonic and/or phasic dopamine release.•We show that 17β-estradiol rapidly ...increases phasic striatal dopamine release.
Studies using in vivo microdialysis have shown that 17β-estradiol (E2) increases dopamine (DA) transmission in the dorsal striatum. Both systemic administration of E2 and local infusion into the dorsal striatum rapidly enhance amphetamine-induced DA release. However, it is not known to what degree these effects reflect tonic and/or phasic DA release. It was hypothesized that E2 acts directly within the DS to rapidly increase phasic DA transmission. In urethane-anesthetized (1.5mL/kg) female rats, we used fast-scan cyclic voltammetry to study the effects of E2 on phasic, electrically-evoked release of DA in the dorsal striatum. Rats were ovariectomized and implanted with a silastic tube containing 5% E2 in cholesterol, previously shown to mimic low physiological serum concentrations of∼20–25pg/mL. DA release was evoked every 1min by delivering biphasic electrical stimulation in the substantia nigra. Local infusions of E2 (244.8pg/μl) into the dorsal striatum increased the amplitude of the electrically evoked DA transients. Behaviorally significant stimuli and events trigger phasic release of DA. The present findings predict that E2 would boost such signaling in behaving subjects.
In this manuscript, we present a facile approach to synthesize a highly active catalyst for the electro-oxidation of ethanol using Pd nanoparticles supported on a Ag–Zn alloy on reduced graphene ...oxide. This nanocomposite material was fabricated via a two-step process of incineration followed by sol-gel synthesis. The physical properties of the catalyst were evaluated using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopies. To understand the catalyst's activity for ethanol oxidation, we performed a series of cyclic voltammetry and electrochemical impedance spectroscopy experiments in alkaline medium. The catalyst exhibited good catalytic activity with a current density of 13.01 mA cm−2, a value seven times higher than the commercial standard Pd/C catalyst and higher than any other previously reported Pd-based catalyst. The results were attributed synergistic effects between the Pd and alloy support along with the large electrochemically active surface area of the material. Taken together, these results suggest that ethanol electrocatalysts based on nanocomposites of Pd, Ag, and Zn is promising candidates for future ethanol fuel cells.
•Facile strategy was used to prepare a support material and catalyst (Pd@Ag–Zn-rGO).•Synthesized Pd@Ag–Zn-rGO composite exhibited good catalytic activity towards ethanol electro-oxidation.•Pd@Ag–Zn-rGO catalyst exhibits lower charge transfer resistance (Rct) at the catalyst surface.
The perhalogenated closo-dodecaborate dianions B12 X12 (2-) (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6 X6 (X=H, F, Cl, Br, I). Whereas oxidation of the ...parent compounds B12 H12 (2-) and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions B12 X12 (2-) with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2 ) yielded the corresponding radical anions B12 X12 (⋅-) (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12 X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12 Cl12 and Na(SO2 )6 B12 Br12 ⋅B12 Br12 . Sublimation of the crude reaction products that contained B12 X12 (X=Cl, Br) resulted in pure dark blue B12 Cl12 or decomposition to red B9 Br9 , respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the B12 X12 (2-) dianions by going from fluorine to bromine as halogen substituent. The oxidation of all B12 X12 (2-) dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions B12 X12 (2-) (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For B12 X12 (2-) (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1.68 and +2.29 V (lSO2 , versus ferrocene/ferrocenium (Fc(0/+) ))), the second process is irreversible (with oxidation potentials ranging from +2.63 to +2.71 V (lSO2 , versus Fc(0/+) )). B12 I12 (2-) showed a complex oxidation behavior in cyclic voltammetry experiments, presumably owing to decomposition of the cluster anion under release of iodide, which also explains the failure to isolate the respective radical by chemical oxidation.
Aromatic hydrocarbons containing one or two dimesitylborylethynyl peripherals possess rich photophysical and electrochemical properties. The inserted ethynediyl (C≡C) spacer canceled steric hindrance ...between the bulky dimesitylboryl groups and the aromatic rings, leading to effective π‐conjugation over the B−C≡C−Ar linkages. Despite the small structural differences, the benzene, naphthalene, and anthracene derivatives showed characteristic photophysical behaviors. More information can be found in the Full Paper by K. Mishiba, Y. Tanaka, and M. Akita on page 5432.
The development of ZnCo alloys appeared as alternative for obtaining layers more resistant than the conventional zinc with a minimum increment of cost. The aim of this work is to study the ...electrodeposition mechanism of the ZnCo alloy on SAE 1020 carbon steel by cyclic voltammetry using two baths with different Zn2+/Co2+ concentration ratios and also to evaluate the corrosion resistance in 0.1 mol L−1 NaCl of electrodeposits obtained potentiostatically using electrochemical techniques as electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic polarization curves. The voltammograms showed two anodic peaks attributed to dissolution of zinc rich ƞ-phases and cobalt, and a cathodic peak related to ZnCo alloy deposition. The nucleation mechanisms were examined by fitting the experimental data (chronoamperometry) into the Scharifker and Hills nucleation models. Scanning electron microscopy (SEM) showed that the electrodeposits obtained for the Zn2+/Co2+ 9:1 ratio presented a structure in the form of hexagonal platelets in comparison to the electrodeposits with Zn2+/Co2+ 12:1 ratio, which presented cauliflower-shaped structures. On the other hand, the electrochemical techniques proved that the electrodeposits obtained for the Zn2+/Co2+ 9:1 ratio at potential of −1450 mV presented the best anticorrosive properties. Structural and chemical characterization of coatings was accomplished by XRD and XRF.
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