Springer Science and Business Media LLC

This paper reports the formation of hybrid polyoxometalate-porphyrin copolymeric films obtained by the electro-oxidation of zinc-β-octaethylporphyrin (ZnOEP) in the presence of a functionalized Dawson-type polyoxometalate bearing two pyridyl groups (POMdbme3,3, Py-POM-Py) which will be compared to the copolymer obtained from ZnOEP and a dipyridyl compound without POM (ibme3,3). The resulting film has been characterized by UV-visible absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Electrochemical quartz crystal microbalance was employed to investigate the poly-porphyrin-POMs deposition mass. Graphical Abstract

Poly 3-methylthiophene (P3MT) modified electrodes have shown an improvement for detecting catecholamines when compared to classical ones. Past work with this polymer electrode suggested the possible presence of “active sites,” which are believed to be the polymer’s center of electrocatalytic activity. The interaction of 1,5-anthroquinone-disolfonic acid (1,5-AQDS) at the P3MT electrode showed a nonreversible behavior resulting in the blocking of “the active sites,” suggesting the specific electcatalytical activity of this polymer is limited to catechol and similar compounds. In order to improve catecholamine detection, two methods of electropolymerization for P3MT were compared under similar conditions; (1) a constant potential for a specific length of time, and (2) potential cycling. It was found that cycling provided a more sensitive CV, i.e. increased number of active sites. Under a controlled pH study (pH range 2–9), the polymer electrode maintained its superior performance, manifested as lower ΔE and higher i, toward catechol over the traditional electrodes. Two different supporting electrolytes were used, sulfate and phosphate, and it was found that in neutral or basic solutions containing phosphate, the oxidation and reduction potentials of catechol shifted to lower values. Solutions containing sulfate exhibited no shift in the oxidation potential at any pH value.

A series of subphthalocyanines with different substituents (RPhO-BSubPc(COOCH3)3) have been synthesized and used as catalysts to catalyze lithium/thionyl chloride (Li/SOCl2) battery. All the compounds are structurally characterized by IR, UV, and element analysis. After adding RPhO-BSubPc(COOCH3)3 into the battery’s electrolyte, the energy and the capacity of the battery are increased by approximately 3.27–40.6 and 10.9–53.2 % than that of the battery in the absence of them. In addition, a three-step hypothetical mechanism is figured out to explain the complex catalytic process. By comparing the images of SEM, it is found that the addition of catalysts makes the lithium chloride layer looser, which is conducive to the transfer of electrons. Moreover, the hypothetical mechanism is confirmed by the results of cyclic voltammetry.

The electrochemical behaviour of steel, copper, and titanium current collectors was studied in aqueous solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at various concentrations, from 0.5 up to 20 m. As the concentration of the electrolyte increases, the electrochemical window of water stability widens according to the “water-in-salt” concept. The metal grids have been studied electrochemically, both under anodic and cathodic conditions, by means of cyclic voltammetry and chronoamperometry. Subsequently, a microscopic analysis with SEM and compositional analysis with XPS was carried out to evaluate the surface modifications following electrochemical stress. We found that copper is not very suitable for this kind of application, while titanium and steel showed interesting behaviour and large electrochemical window.

The paper presents several experimental results regarding the electrodeposition of Cu-Sn alloy coatings prepared in ChCl-EG deep eutectic solvents (DESs). The electrochemical behavior of Cu2+ and Sn2+ on glassy carbon electrode (GC) was studied by cyclic voltammetry (CV). The nucleation mechanism of Cu2+ and Sn2+ at different potentials was analyzed by the potentiostatic current density transient (chronoamperometry (CA)). Surface and phase composition of Cu-Sn alloy coating were characterized by scanning electron microscopy (SEM/DEX) and X-ray diffraction (XRD). The corrosion resistance of Cu-Sn coating was studied by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS). From the results, it can be seen that the Cu-Sn alloy can be co-deposited at the potential from − 0.5 to − 0.8 V. The surface of the coating showed a different microstructure when the deposition potential changed. With the negative shift of deposition potential (− 0.5 to − 0.8 V), the particle size of the coating decreased. Comparison in the corrosion behavior of the coatings showed that the change of Sn content had an effect on the corrosion resistance of Cu-Sn alloy. The thickness of the coating (from 7 to 11 μm) was obtained by electrodeposition at − 0.8 V (1 h).

Nanoporous Ag@TiO2 composites with core-shell structure were successfully prepared through dealloying the melt-spun Al-Ag-Ti ribbons in NaOH aqueous solution. The results revealed that TiO2 shell with thickness of about 2 nm was formed in situ on the Ag ligaments. Ti3+ and Ag+ species co-existed after the dealloyed samples were calcined at 873 K, which had significant influence on the catalytic performance. The electrochemical results showed that the nanoporous Ag@TiO2 composites significantly promoted the direct oxidation of BH4 − superior to pure Ag. The enhanced catalytic activity could be attributed to the strong interfacial effects between the ligaments and TiO2 shells.

In this study, we successfully fabricated LiCo1-xDyxO2 (where x = 0.0–0.5) samples and investigated the structural and electrochemical properties. The Dy-substituted LiCoO2 samples were characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Fourier-transform infrared (FTIR), and Raman measurements before and after cycling. The lattice volume and effective magnetic moment were increased by the substitution of the Dy ions in the structure. The capacity fading mechanism of Dy-substituted LiCoO2 via ex situ X-ray diffraction, XAS, Raman and FTIR spectroscopy were investigated. According to the electrochemical performance of the batteries, the x = 0.04 electrode had better cycling properties up to 400 cycles, which are better than that of the pure LiCoO2. We suggested that the critical number of Dy in LiCoO2 facilitates the Li-diffusion by increasing lattice volume. According to the battery performance temperature dependence analysis from 10 to 50 °C, the electrolyte just below degradation temperature shows better cycling since the ions are more mobile in this case.