•NiCu alloys with various Cu contents were prepared by powder metallurgy method.•NiCu alloy exhibits chemical composition related synergistic effect for HER activity.•Ni10Cu alloy electrode presents a most efficient activity for HER.•Two time constants are observed in Nyquist curve and both of them related to the kinetics of HER.NiCu bimetallic alloys with Cu content of 5, 10, 20, 30 and 50 wt% are prepared by powder metallurgy method, which consisted of powder mixing, pressing and sintering processes. The X-ray diffraction (XRD) measurement confirms that all the five NiCu alloys possess the f.c.c. structure. The hydrogen evolution reaction (HER) activity of the prepared NiCu alloy electrodes was studied in 6 M KOH solution by cathodic current-potential curves and electrochemical impedance spectroscopy (EIS) techniques. It was found that the electrocatalytic activity for the HER depended on the composition of NiCu alloys, where Ni10Cu alloy exhibited considerably higher HER activity than Ni plate and other NiCu alloys, indicative of its chemical composition related intrinsic activity.

Zr-incorporated CaO-P2O5-SiO2-SrO-ZrO2 (BG-Zr) bioactive glasses were prepared through the sol-gel process by adding zirconium oxychloride to the synthesis batch as the zirconia precursor. The added amount of ZrO2 was 5, 8 and 11 wt%, respectively, to replace the same amount of CaO. The effect of ZrO2 on the solubility, bioactivity and structural properties of BG-Zr were investigated. The differential thermal analysis (TG/DTA) and X-ray diffraction (XRD) indicated that the addition of ZrO2 to the base glass composition increased its crystallization temperature as well as weakened its crystallization tendency. Zr4+ ion substituted for Ca2+ favors covalent O-Zr-O bonding formation, making the glass network stronger, and thus BG-Zr glasses exhibit enhanced bending strength. Immersion tests in hydroxymethylaminomethane (Tris) buffer and simulated body fluid (SBF) show BG-Zr glasses to exhibit slower dissolution rate and lower rate of apatite formation with increasing ZrO2 content compared to the base glass, which is likely associated with their structure stabilization and lower solubility.

•Ni–Mo–Cu coating electrode was prepared by constant current electrodeposition.•Ni–Mo–Cu alloy coating electrode presents a most efficient activity for HER.•Parameters affecting the HER activity are systematically investigated.•A synergistic effect and high surface area contribute to the high HER efficiency.Ni–Mo–Cu alloy coating electrode was prepared on copper substrate by constant current electrodeposition and characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The electrochemical characterization for hydrogen evolution reaction (HER) was investigated by cyclic voltammetry (CV) curves, linear sweep voltammetry (LSV) curves and electrochemical impedance spectroscopy (EIS) techniques. Parameters affecting the electrocatalytic activity for the HER are systematically investigated. Results show the Ni–Mo–Cu coating by the introduction of Cu has a rough and cauliflower-like structure and presents a most efficient activity for HER in comparison with binary Ni–Mo electrode. Its remarkably enhanced catalytic activity is attributed to the high surface area as well as synergistic interaction between Ni, Mo and Cu.

Biodegradable Mg-based metal matrix composite (Mg-MMC) reinforced by MgO ceramics and Mg–Zn intermetallics were prepared by in situ reaction using a powder mixture of pure magnesium and 20 wt% ZnO as raw materials. The corrosion behaviour of Mg-MMC was evaluated by electrochemical measurements and immersion tests in Hanks’ solution. Results show that the newly developed Mg-MMC is composed of α-Mg matrix and uniformly distributed MgO ceramic and Mg–Zn intermetallics in matrix as reinforcements. The Mg-MMC possesses a corrosion behaviour comparable to pure magnesium and exhibits enhanced improvement in mechanical properties and corrosion resistance.Highlights► Mg-based metal matrix composite (Mg-MMC) reinforced by MgO ceramics and Mg–Zn intermetallics was fabricated by in situ sintering reaction. ► Mg-MMCs exhibit significant improvement in mechanical properties and corrosion resistance relative to pure Mg. ► The Mg-MMC might be a promising candidate as full degradable biomedical materials.

In this study, binary Mg–Zn alloys were fabricated with high-purity raw materials and by a clean melting process. The effects of Zn on the microstructure, mechanical property and corrosion behavior of the as-cast Mg–Zn alloys were studied using direct observations, tensile testing, immersion tests and electrochemical evaluations. Results indicate that the microstructure of Mg–Zn alloys typically consists of primary α-Mg matrix and MgZn intermetallic phase mainly distributed along grain boundary. The improvement in mechanical performances for Mg–Zn alloys with Zn content until 5% of weight is corresponding to fine grain strengthening, solid solution strengthening and second phase strengthening. Polarization test has shown the beneficial effect of Zn element on the formation of a protective film on the surface of alloys. Mg–5Zn alloy exhibits the best anti-corrosion property. However, further increase of Zn content until 7% of weight deteriorates the corrosion rate which is driven by galvanic couple effect.Highlights► The microstructure of Mg–Zn alloy consists of α-Mg matrix and MgZn intermetallic. ► The addition of Zn to Mg up to 5 wt.% has beneficial effect. ► A network structure of MgZn intermetallic phase exhibits deteriorated effect.

MgO coatings were prepared on magnesium alloy surface by an anodic electrodeposition process in concentrated KOH solution followed by heat treatment in air. The phase composition and microstructure of the as-formed MgO coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behavior of the MgO-coated samples was evaluated by electrochemical measurements and immersion tests in Hanks’ solution. The results showed that the MgO-coated Mg alloy exhibited a much superior stability and lower corrosion rate, and thus enabled to improve the corrosion resistance, whereas the bare Mg alloy suffered from severely localized corrosion attack.Research highlights► Dense MgO coatings with a thickness of 25 μm on magnesium alloy substrate are produced by an anodic electrodeposition process in KOH alkaline solution and subsequent thermal treatment ► Both electrochemical measurements and immersion tests in Hanks’ solution show that MgO coatings could suppress the corrosion process by preventing the corrosive ions from transferring or diffusing to the magnesium alloy substrate, and thus improve the corrosion resistance ► The anodic electrodeposition process might be an alternative method to PEO to produce layers that could provide better corrosion protection to magnesium alloys

This work describes a new approach to the construction of an amperometric biosensor for hydrogen peroxide detection based on in situ electrosynthesized gold/polyaniline core–shell nanocomposites on conducting ITO electrode. The immobilization of the enzyme, horseradish peroxidase (HRP), on the polyaniline nanofilm was carried out by electrostatic attachment approach. Results showed that the immobilized HRP exhibited enhanced performance toward the reduction of H2O2, in comparison with other bulk polyaniline (PANI)-based H2O2 biosensor and metallic nanoparticles incorporated PANI systems. The resulting biosensor shows a fast amperometric response (<2 s) to H2O2. A linear range from 0.2 to 80 μM for the detection of H2O2 was observed with a sensitivity of 20.5 μA/mM and a detection limit of 0.16 μM at a signal-to-noise ratio of 3. Moreover, the biosensor has a good reproducibility, and long-term stability.