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As a representative composite metal oxide belonging to a perovskite, strontium titanate (SrTiO3) possesses the merits of chemical stability, low toxicity and low cost, endowing it with significant application potentials in environmental remediation, clean energy generation and valuable chemical production from greenhouse gas conversion. However, the pure-phase SrTiO3 suffers from many fatal weaknesses, especially the wide energy bandgap and low photoexcited electron–hole pair separation efficiency, thus limiting its photocatalytic performance and large-scale applications. To address this issue, researchers have made great efforts to modify the electronic and physicochemical structure of SrTiO3. In particular, doping treatments have attracted considerable attention, but some problems still block effective doping, while impropriate doping might worsen the photocatalytic performance of SrTiO3 by introducing the photogenerated hole–electron pair recombination centres. Consequently, many challenges remain for this research topic that is undergoing an intense study. This short review presents the hot spots of appropriate doping treatments of SrTiO3 for photocatalytic performance enhancement over recent years. Different kinds of doping species are systematically discussed. The current problems that remain are summarized and analysed, and the perspectives for the rational doping of SrTiO3 are presented. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) films have attracted extensive attention in Mg alloy anti-corrosion due to their unique physical barrier function and ion exchange performance. However, most of the LDH films on Mg alloy have problems of harsh preparation conditions, poor anti-corrosion stability, and poor adhesion. In this paper, a typical Li–Al-alanine (Ala) LDH film has been successfully prepared on AZ91D Mg alloy surface under milder conditions using multi-arc ion plating and in-situ dipping for the first time. Then an improved vacuum impregnation further modified the Li–Al-Ala LDH film in an ethanol solution of stearic acid (SA) to improve its protective stability. The potentiodynamic polarization curves and electrochemical impedance spectra (EIS) showed that the Li–Al-Ala LDH/SA film's corrosion resistance is more than three orders of magnitude higher than that of the blank Mg alloy in 3.5 wt% NaCl, showing a highly increased corrosion resistance. The long-term immersion experiments found that the surface structure and corrosion resistance of the Li–Al-Ala LDH/SA film did not change much after immersion in 3.5 wt% NaCl for 432 h. The bonding force between the film and the Mg alloy substrate can reach grade 0 based on the standard from International Standardization Organization (ISO). And the hydrophobicity of the film can remain stable with the water contact angle (WCA) being steady at about 140° after a certain distance of external abrasion, showing excellent mechanical wear resistance. The study provides a new milder approach to fabricating superhydrophobic LDH films with durable anti-corrosion resistance, good adhesion, and mechanical stability on Mg alloy surface. [ABSTRACT FROM AUTHOR]

Antiferroelectric (AFE) ceramic capacitors are the key components in high-power system, while the nonlinear dielectric property imposes an important impact on discharge performance. In particular, the microstructure, nonlinear dielectric behaviors and discharge properties of (Pb0.87Ba0.08Sr0.02La0.02) (Zr0.65Sn0.27Ti0.08)O3 AFE ceramics, which are fabricated by the solid state reaction, have been studied in detail. The results show that its energy storage density, current density and power density gradually increase with the electric field, and a significant non-linear increase near the switching electric field (EAF) can be observed. In addition, the power density and dielectric tunability show up an increasing tendency first until reach the peak and then decrease. It has been found that both peaks occurs around 70 °C. It is worth noting that the temperature exhibits relevance on the discharge period when the electric field is low. At 20 kV/cm, the period is only 150 ns at 20 °C and 201 ns at 110 °C, respectively. With regard to 50 kV/cm, the period becomes stable around 215 ns regardless of the temperature change. This phenomenon is reported for the first time, and its main mechanism needs further study. The results provide a new idea for understanding the influence of AFE nonlinear dielectric behavior on discharge performance and an experimental basis for choosing the best working temperature and electric field. [ABSTRACT FROM AUTHOR]

The twinning mechanism of Al solid solutions is comprehensively investigated via the first-principles method. The relative stability of C and H atoms at tetrahedral and octahedral centers is discussed. Moreover, the interaction energies between solute atoms at different atomic layers and generalized stacking-fault structures are calculated. Results indicate that the stable occupation of C atom exists at the octahedral center rather than at the tetrahedral center. By contrast, the H atom stably exists at the tetrahedral center rather than at the octahedral center. Both atoms can effectively reduce the minimum energy barrier of dislocation nucleation, thereby promoting dislocation nucleation. The C atom more easily promotes dislocation nucleation than the H atom. Furthermore, both atoms are repelled by the stacking-fault plane. However, they are more likely to be segregated in the second neighboring layer of unstable stacking fault, intrinsic stacking fault (ISF), and unstable twinning fault (UTF) structures. Charge density measurements reveal that the twinning process is likely inhibited because of the strong local chemical bonding around the UTF layer from the ISF structure to the UTF structure. High concentrations of both atoms inhibit the twinning deformation at crack tips and grain boundaries, but they have almost no effect on the twinning deformation inside the grains. This study provides deep insights into the twinning deformation mechanism of face-centered-cubic alloy systems. [ABSTRACT FROM AUTHOR]

Recent experiments have proven that the 9R phase can dramatically improve the mechanical properties of Al alloys. This work aims to investigate the effects of solute atoms on 9R phase stabilization in Al alloys through first-principles calculations. Based on two distribution models of solute atoms, namely, the uniform distribution and the Fermi–Dirac distribution models, we discuss the influences of solute concentrations and finite temperatures on the increments of intrinsic stacking fault energy in the 9R phase structure. The results reveal that high-concentration solute atoms (Ga, Ge, Sc, Si, Sn, Sr, and Y) can promote 9R phase stabilization. Among them, the Sr atom shows the highest performance, but its stabilization can be disrupted by high temperature. These findings serve as a valuable guidance for designing and using high-performance Al alloys with the 9R phase structure. [ABSTRACT FROM AUTHOR]

With the energy crisis and resource depletion nowadays, novel, highly performing, and cost-effective semiconductors are in urgent demand for efficiently harvesting solar energy for photoelectrochemical applications. Herein, this study presents low-cost anatase TiO hollow nanoparticles as prepared by a critical liquid-phase deposition (LPD) processing combined with a hydrothermal reaction and calcination processing, without involving any templates. The additional LPD processing not only makes the resulting samples more visible light responsive, but also results in hollowing the TiO nanoparticles (nanosheets vs. hollow nanoparticles). Importantly, commercial TiO powder is employed as the starting material to achieve the final synthesis of TiO hollow nanoparticles, making it scalable and cost-effective for production and applications. As a by-product, the fluoride, formed during the preparation process, is assumed to play a significant role in hollowing through chemically induced self-transformation and Ostwald ripening, in addition to enhancing the crystallinity. The beneficial structural evolution to the hollow nanoparticles enables the improvement of the photoelectrochemical performance through impressive inhibition of the recombination of the photoelectrons and holes, which is well evidenced by I and EIS (Nyquist plot), as well as by I- V curve and electron lifetime evaluations as for the assembled DSSCs with the prepared TiO hollow nanoparticles under simulated sunlight illumination (50 mW/cm). [ABSTRACT FROM AUTHOR]

For the first time, a hierarchical phosphor YO:Eu/MCM-41/YVO:Eu, with a core-shell-core heterostructure, is presented in this study. Synergistically bridging the phosphors YO:Eu (as an inner core) and YVO:Eu (as an outer core) by amorphous SiO, i.e., MCM-41 (with ordered mesoporous channels) leads to the generation of the core-shell-core heterostructure with enhanced red emission and tunable, broadened-band response to excitation. The novel structure of the core-shell-core hierarchical material is clarified through various characterization methods including X-ray diffraction analysis, transmission electron microscopy, selected-area electron diffraction and N adsorption-desorption measurements. Significantly, through temperature-dependent fluorescence investigation, it is found that our core-shell phosphor (YO:Eu/MCM-41) exhibits impressive fluorescence stability against temperature variation (27-227 °C) due to the protective effect resulting from MCM-41. By contrast, lowered stability can be noted for the core-shell-core phosphor (YO:Eu/MCM-41/YVO:Eu), especially when the temperature is higher than 100 °C, owing to the outer core (YVO:Eu nanoparticles) that is directly exposed to heat. Such a kind of luminescent materials holds substantial promise for labeling the organisms that are vulnerable to short-wavelength UV light irradiation. Additionally, potential intelligent systems can be expected to be designed on the basis of the fluorescence mutation as triggered by the temperature of 100 °C. [ABSTRACT FROM AUTHOR]

For the first time, this study presents solar photocatalytic processing of the real dye wastes remaining after finishing polyester/cotton (P/C) blends, rather than a pure organic dye solution as widely reported. A commonly used microencapsulation-based one-bath dyeing is investigated systematically, in order to simulate the real dyeing environment and to generate real dye wastes. The generated dye wastes are subsequently tackled by facile cotton fabric-based photocatalytic degradation involving a visible light-active TiO photocatalyst under solar light. Importantly, such a TiO photocatalyst is prepared without any calcination, doping, or coupling with plasmonic metal nanoparticles or narrow-band-gap semiconductors. As a result, the present visible light-responsive cotton fabric-based photocatalytic degradation of the simulated real dye wastes is expected to stimulate various industries for achieving simultaneous effective dyeing and processing of the dye wastes remained. This study also contributes to energy saving and environmental protection. [ABSTRACT FROM AUTHOR]

Graphene materials have been extensively verified as a good adsorbent for tackling wastewater containing various aromatic pollutants; however, little attention has been paid to understanding the graphene-based adsorption mechanism. Here, a systematic work is performed to prepare a series of graphene oxide (GO)-incorporated polyacrylamide hydrogels, with a three-dimensional (3D) monolithic structure, followed by in situ conversion of GO to reduced graphene oxide. Such a method not only enables the prevention of irreversible aggregation of graphene sheets during the in situ reduction, but also facilitates the clarification of the relationship between the structure and adsorption properties of the graphene materials. This work presents two kinds of graphene-based 3D monolithic adsorbents for either selective separation of the cationic aromatic pollutant from anionic one or uptake both of them for the total purification purpose. More importantly, we effectively unravel that the sp-conjugated carbon network of the graphene materials plays a pivotal role in purifying the aromatic organic pollutants through π-π stacking interactions that outstrip electrostatic attraction interactions. Therefore, the present work is expected to provide an impetus toward exploration of high-performance graphene-based materials for various applications, especially environmental remediation, on the basis of effectively impeding self-aggregation of graphene sheets and judiciously modulating their intrinsic structure. [ABSTRACT FROM AUTHOR]

Organic compounds that contain nitrogen are very important intermediates in pharmaceutical and chemical industry. Hydroamination is the reaction that can form C–N bond with high atom economy. The research progress in metals catalyzed hydroamination of alkenes and alkynes from the perspective of reaction mechanism is categorized and summarized. [ABSTRACT FROM AUTHOR]