Two-dimensional (2D) graphitic-C3N4 (g-C3N4) was successfully hybridized with one-dimensional (1D) flux-grown Na-modified K2Ti6O13 nanobelts (Na-K2Ti6O13 NBs) for the first time to construct novel 1D/2D Na-K2Ti6O13/g-C3N4 heterostructured photocatalysts using a facile mixing–calcination method. The heterostructured Na-K2Ti6O13/g-C3N4 composites with three-dimensional (3D) hybrid architectures exhibited a remarkably enhanced photocatalytic efficiency for organic pollutant degradation in comparison with pure Na-K2Ti6O13 and g-C3N4 under both simulated sunlight and visible-light irradiation (λ > 420 nm), which could be mainly attributed to the synergistic effects between Na-K2Ti6O13 and g-C3N4 including more efficient interfacial charge transfer, longer lifetimes and the stronger oxidation and reduction ability of photogenerated charge carriers, fundamentally originating from the formation of Na-K2Ti6O13/g-C3N4 heterojunctions based on the well-matched energy-band structures. Moreover, the Na-K2Ti6O13/g-C3N4 hybrids showed good stability and reusability for the photocatalytic degradation of organic pollutants. Finally, the possible mechanisms responsible for the improved simulated sunlight and visible-light photocatalytic performance were also investigated, respectively, based on the results of PL spectra, time-resolved fluorescence decay spectra, radical species trapping experiments, ESR spectra and PL-TA measurements. Overall, this work will not only be beneficial for the design and development of more efficient visible-light-responsive g-C3N4-based composites for solar energy conversion and environmental remediation but will also be influential in optimizing the visible-light photocatalytic activity of wide-band-gap 1D titanate nanomaterials to meet the requirements of practical applications.

LiF-NaF-KF melt is used to investigate the feasibility of using electrochemical methods to characterize and remove trace amounts of oxygen ions. Electrochemical methods including cyclic voltammograms and chronoamperometry are applied to characterize the oxidation processes of the trace oxygen ions in LiF-NaF-KF melt. The results show that the anodic peak currents vs. the square roots of scan rates is linearity passing through the origin, indicating the oxidation of oxygen ions is controlled by ions diffusion process. The dependency of the anodic peak currents vs. the concentrations of oxygen ions is also linearity when the concentration is no more than 1200 ppm. So the anodic peak current can be used to determine the oxygen ions content in the melt online. The peak currents of oxygen ions oxidation are gradually reduced after 3 h, 8 h and 20 h constant-potential electrolysis. Oxygen ions concentration is reduced to 200 ppm in LiF-NaF-KF melt after 20 h constant-potential electrolysis.

A single-phase Li4Ti5−xFexO12 (x = 0, 0.1, 0.2, 0.3) with spinel structure has been synthesized in LiCl–KCl molten salts with a stoichiometric molar ratio of 4:5:x/2:20 LiOH·H2O, TiO2, Fe2O3, LiCl–KCl (x = 0, 0.1, 0.2, 0.3). The effects of Fe2O3 on the phase structure, morphology and particle size of Li4Ti5O12 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) equipped with energy dispersive spectroscope (EDS). The electrochemical performances of the Li4Ti5−xFexO12 were characterized by charge/discharge curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results show that Fe2O3 homogenously distributes in the crystal lattice of Li4Ti5O12 and slightly increases the lattice parameters due to Fe3+ ion doping. The addition of 0.1 molar ratio Fe2O3 to Li4Ti5O12 reduced the average particle size of Li4Ti5O12 from 1 μm to about 200 nm. The obtained Li4Ti4.8Fe0.2O12 was used as anode material for a lithium-ion battery, presenting the capacity of 173.7 mA h g−1 at 0.2 C—approaching the theoretical capacity of Li4Ti5O12 (175 mA h g−1)—and giving a capacity of 103.4 mA h g−1 at 10 C, much larger than the value of pure Li4Ti5O12 (28.7 mA h g−1). This is well explained by the EIS and CV results.

The corrosion behaviors of 304SS, 316LSS, and Q235A in LiCl-KCl melts were investigated at 450°C by Tafel curves and electrochemical impedance spectroscopy (EIS). 316LSS shows the best corrosion resistance behaviors among the three materials, including the most positive corrosion potential and the smallest corrosion current from the Tafel curves and the largest electron transfer resistance from the Nyquist plots. The results are in good agreement with the weight losses in the static corrosion experiments for 45 h. This may be attributed to the better corrosion resistance of Mo and Ni existing as alloy elements in 316LSS, which exhibit the lower corrosion current densities and more positive corrosion potentials than 316LSS in the same melts.

Electrodeposition of aluminum from an AlCl3-EMIC ionic liquid with or without the addition of saturated LaCl3 was carried out by both direct- and pulse-current plating methods. The effects of various parameters, including current density, pulse frequency, current on/off duration (ton and toff), and temperature, on deposit morphology and crystal size were investigated. Deposits prepared by pulse-current plating gave a brighter and flatter surface than those prepared by direct-current plating at appropriate pulse current parameters. Temperature and pulse–current frequency (toff) were shown to significantly affect deposit morphology. Coalescence of grains during toff periods in the pulse current plating was observed, especially at temperatures above 60 °C. Increasing the temperature from 25 to 90 °C caused an increase in deposit grain size and resulted in a change of grain shapes from a small sphere-like form to a feather-like form. As a result, the adhesion of the deposited aluminum to the substrate was lowered. Smaller grain sizes and well-adhered deposits were achieved at lower temperatures. For example, deposition at 25 °C resulted in the smallest crystal size of about 0.3 μm under the conditions of ton = 80 ms, toff = 20 ms, and i = 8 mA/cm2. Furthermore, the addition of LaCl3 to the melt at 60 °C effectively reduced the porosity and improved compactness of deposits.

Highly crystalline and idiomorphic CoTiO3 single crystals with a well-defined polyhedral morphology were grown successfully for the first time by a facile flux method. Herein, the effects of the molten salt type and cobalt precursor on the phase composition, crystallization habit and morphology of the CoTiO3 products were also investigated. Importantly, using the flux-grown CoTiO3 crystal as the visible-light sensitizer due to its narrow band gap to couple with graphitic carbon nitride (g-C3N4) by a direct in situ thermal induced polycondensation route, novel CoTiO3/g-C3N4 composite photocatalysts were obtained. The as-synthesized samples were systematically characterized by XRD, EDS, SEM, TEM, SAED, HRTEM, FT-IR, XPS, DRS and PL techniques. The results revealed that CoTiO3 polyhedral crystals were closely combined with g-C3N4 nanosheets leading to the formation of a heterojunction structure at the interface between CoTiO3 and g-C3N4. Photocatalytic evaluation showed that the heterostructured CoTiO3/g-C3N4 composite exhibited much higher photocatalytic activity for the degradation of methyl orange under visible light irradiation than that of individual CoTiO3 and g-C3N4, which could be mainly ascribed to the synergistic effect between CoTiO3 and g-C3N4, including the enhanced visible-light harvesting ability and more efficient separation and longer lifetime of photogenerated charge carriers. Furthermore, the composite photocatalyst showed an excellent stability and reusability during four successive cycles. Finally, a possible mechanism responsible for the charge separation and improved photocatalytic activity was proposed.