Electrochemical formation of carbon nano-powders with various porosities in molten alkali carbonates

The electrochemical reduction of molten Li-Na-K carbonates at the eutectic composition was (43.5/31.5/25 mol%) performed in the range 450-700 °C. The analysis of the electrochemical mechanism was done by cyclic voltammetry with an inert vitreous carbon electrode. “Quasi-spherical” carbonaceous particles were obtained with average diameter comprised between 30 and 50 nm. The specific surface area as well as the crystallinity and morphology of the powders were strongly influenced by the operating conditions, i.e. potential deposition, temperature of the molten carbonates, temperature of the drying process after washing. The carbon prepared in our experimental conditions contains micro-, meso- and macroporisty. The proportion of each one is strongly dependent on the operating deposition conditions. The highest specific surface area value (1315 m² g⁻¹) was obtained with carbon powder deposited at 450 °C for an applied potential of −6 V and dried at 600 °C under vacuum after washing.     

Electrochemical behavior and its electrocatalytic properties of chemically modified electrode with Keggin-type [SiNi(H2O)W11O39]

A monolayer of Keggin-type heteropolyanion [SiNi(H₂O)W₁₁O₃₉]⁶⁻ was fabricated by electrodepositing [SiNi(H₂O)W₁₁O₃₉]⁶⁻ on cysteamine modified gold electrode. The monolayer of [SiNi(H₂O)W₁₁O₃₉]⁶⁻ modified gold electrode was characterized by atomic force microscopy (AFM) and electrochemical method. AFM results showed the [SiNi(H₂O)W₁₁O₃₉]⁶⁻ uniformly deposited on the electrode surface and formed a porous monolayer. Cyclic voltammetry exhibited one oxidation peak and two reduction peaks in 1.0 M H₂SO₄ in the potential range of −0.2 to 0.7 V. The constructed electrode could exist in a large pH (0-7.6) range and showed good catalytic activity towards the reduction of bromate anion (BrO₃⁻) and nitrite (NO₂⁻), and oxidation of ascorbic acid (AA) in acidic solution. The well catalytic active of the electrode was ascribed to the porous structure of the [SiNi(H₂O)W₁₁O₃₉]6⁻ monolayer.     

Electrochemical degradation of bisphenol A on different anodes

Laboratory experiments were carried out on the kinetics, pathways and mechanisms of electrochemical (EC) degradation of bisphenol A (BPA) on four types of anodes, Ti/boron-doped diamond (BDD), Ti/Sb-SnO₂, Ti/RuO₂ and Pt. There were considerable differences among the anodes in their effectiveness and performance of BPA electrolysis. BPA was readily destructed at the Ti/Sb-SnO₂ and Ti/BDD anodes, the Pt anode had a moderate ability to remove BPA, and the Ti/RuO₂ anode was incapable of effectively oxidising BPA. The intermediate products of EC degradation of BPA were detected and quantified by high-performance liquid chromatography (HPLC), and a general BPA degradation pathway was proposed based on the analytical results. It was suggested that OH radicals produced by water electrolysis attacked BPA to form hydroxylated BPA derivatives that were then transformed into one-ring aromatic compounds. These compounds underwent ring breakage, which led to the formation of aliphatic acids that were eventually mineralised by electrolysis to CO₂. Compared to the Pt and Ti/RuO₂ anodes, the Ti/Sb-SnO₂ and Ti/BDD anodes were found to have higher oxygen evolution potentials and higher anodic potentials for BPA electrolysis under the same current condition. However, the stability and durability of the Ti/Sb-SnO₂ anode still needs to be greatly improved for actual application. In comparison, with its high durability and good reactivity for organic oxidation, the Ti/BDD anode appears to be the more promising one for the effective EC treatment of BPA and similar endocrine disrupting chemical (EDC) pollutants.     

黄铜表面图案的电化学蚀剂

黄铜表面的图案、文字用电化学蚀刻效果好、生产率高、成本低。文中介绍了黄铜电化学蚀刻的原理、电解液配方和工艺参数。     

Research Impact on Emerging Quantum Materials for Electrochromic Applications

Electrochromic devices (ECDs), which can dynamically vary optical properties under applied specific voltage, have been actively studied for use in applications requiring human comfort and energy efficiency (i. e. smart windows and electronic displays). In order to improve the electrochromic (EC) performances, many researchers have been using nanomaterials. In this respect, in the present study, we highlight some of valuable examples using WO₃ from unique nanostructures to quantum dots (QDs) and discuss the core relationship between nanostructuring and EC performances. In particular, the present study proposes major impact on the novel approach using QDs to upgrade technical value and application of ECDs.     

Membranbrennstoffzellen

With the development of polymer membranes suitable as proton‐conducting electrolytes, membrane fuel cells are now successfully applied in various areas. Depending on the application, the service life, the power density or other system aspects are optimized. Common to all applications is the requirement to reduce costs, which, however, plays a decisive role especially in passenger cars. The development of the membrane fuel cell has now reached a high technical level, but political flanking measures are still required to launch it on the market. This applies both to the hydrogen infrastructure for fuel cell vehicles and to the promotion of fuel cell‐based combined heat and power generation.     

Amperometric determination of bisphenol A in milk using PAMAM–Fe3O4 modified glassy carbon electrode

A simply and sensitively electroanalytical method for determination of bisphenol A (BPA) using poly(amidoamine) (PAMAM) and Fe₃O₄ magnetic nanoparticles modified glassy carbon electrode (GCE) was presented. Compared with bare electrode, PAMAM–Fe₃O₄ modified electrode not only significantly enhanced the oxidation peak current of BPA, but also lowered the oxidation overpotential, suggesting that the modified electrode can remarkably improve the determining sensitivity of BPA. Factors influencing the detection processes were optimised and kinetic parameters were calculated. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 1 × 10⁻⁸–3.07 × 10⁻⁶ M with the correlation coefficient of 0.9996 and the detection limit of 5 × 10⁻⁹ M. The current reached 95% of the steady-state current within about 6 s. The proposed method was successfully applied to determine BPA in milk samples and satisfactory results were obtained.     

Konzept einer autarken elektrischen und thermischen Energieversorgung auf Basis von Photovoltaik

A photovoltaic system could supply a single-family house with electrical power, warm water, and room heat if the energy would be distributed over the year to suit the load profile. However, storage systems for this are not state of the art yet. A concrete example is used to estimate which parameters such a power storage system should have. A suitable electrochemical reaction system based on inorganic salt mixtures is proposed. The German Federal Ministry of Education and Research is currently funding the development of a world storage facility based on the same reaction system.     

Chemistry enhanced shear thickening polishing of Ti–6Al–4V

To obtain the great surface quality of Ti–6Al–4V and achieve high efficiency in the polishing process, the chemistry enhanced shear thickening polishing (C-STP) was proposed, and the polishing performance of different pH slurry was studied. The results show that the material removal rate gradually increases as the pH value decreases from 10 to 1, and the best surface quality is obtained at pH 2. The corrosion current density and potential were measured by potentiodynamic polarization under three typical pH values. It is confirmed that the most massive corrosion rate presents at pH 2, and the passive film is most susceptible to be produced at pH 10. The reaction resistance was measured by electrochemical impedance spectroscopy to clarify the polishing mechanism. Under acidic conditions, the chemical reaction product on the surface can be quickly removed by mechanical action of the abrasive. On the contrary, the passive film formed on the surface under the alkaline condition is difficult to be removed. The corrosion reaction products were determined by X-ray photoelectron, and the chemical reaction under acid-base environment was derived. MRR reached 107.3 nm/min under the selected process parameters, and the surface roughness (S_a) is reduced from 124 nm to 8.6 nm within 15 min.     

Effect of Cr on the hydrogen storage and electronic properties of BCC alloys: Experimental and first-principles study

Inventing an effective method to store large amounts of hydrogen at room temperature is one of the key challenges in developing a hydrogen-based economy. Metal hydrides have attracted attention owing to their promising hydrogen storage capabilities. We have systematically studied the structural and electronic properties of mechanically synthesized Ti_0.5V_1.5-xCr_x (0 ≤ x ≤ 0.3) alloys and investigated the influence of the addition of Cr atoms on the hydrogen storage properties of vanadium-rich body-centered-cubic (V-BCC) alloys. X-ray diffraction (XRD) results indicate that all alloys are composed of BCC main phase, with the lattice parameters exhibiting no change following chemical modification. The kinetic measurements have revealed that Cr-containing alloys exhibit improved hydrogen uptake. X-ray photoelectron spectroscopy (XPS) measurements have shown that the addition of Cr has a significant effect on the anti-oxidation properties of V-BCC alloys, increasing their chemical activity and thus enhancing the hydrogen storage properties. Moreover, XPS results elucidate the role of activation of the studied materials. Additionally, the electrochemical properties of the negative electrodes (as part of Ni-MH_x secondary batteries) made of Ti_0.5V_1.4-xNi_0.1Cr_x (0 ≤ x ≤ 0.3) system have been studied by cyclic charge-discharge and demonstrate that doping of the V-BCC alloys with Cr can significantly improve the cycle-life stability of anode that exhibits similar discharge performance up to 50 cycles. First principles simulations are used to analyse the changes in the electronic density of states close to the Fermi level, as a function of Cr concentration, as well as binding energies and structural changes upon hydrogen absorption. Furthermore, ab initio studies confirmed that H absorption is favoured with increasing Cr-content. Our study highlights the importance of the addition of Cr to V-BCC alloys on both solid-gas and electrochemical hydrogenation reactions.