Template-free hydrothermal synthesis of MgWO4 nanoplates and their application as photocatalysts

Investigation of the photoluminescent properties, scintillation behaviour and toxicological profile of various magnesium tungstate nanoscale motifs

We have synthesized several morphologies and crystal structures of MgWO₄ using a one-pot hydrothermal method, producing not only monoclinic stars and large nanoparticles but also triclinic wool balls and sub-10 nm nanoparticles. Herein we describe the importance of reaction parameters in demonstrating morphology control of as-prepared MgWO₄. Moreover, we correlate structure and composition with the resulting photoluminescence and radioluminescence properties. Specifically, triclinic-phase samples yielded a photoluminescence emission of 421 nm, whereas monoclinic-phase materials gave rise to an emission maximum of 515 nm. The corresponding radioluminescence data were characterized by a broad emission peak, located at 500 nm for all samples. Annealing the wool balls and sub-10 nm particles to transform the crystal structure from a triclinic to a monoclinic phase yielded a radioluminescence (RL) emission signal that was two orders of magnitude greater than that of their unannealed counterparts. Finally, to confirm the practical utility of these materials for biomedical applications, a series of sub-10 nm particles, including as-prepared and annealed samples, were functionalized with biocompatible PEG molecules, and subsequently were found to be readily taken up by various cell lines as well as primary cultured hippocampal neurons with low levels of toxicity, thereby highlighting for the first time the potential of this particular class of metal oxides as viable and readily generated platforms for a range of biomedical applications.

Tuning the Nanoparticle Interfacial Properties and Stability of the Core-Shell Structure in Zn-Doped NiMoO4@AWO4

The ability to tune the interfacial region in core-shell nanocomposites with a surface reconstruction as a source for surface energy (de)stabilization is presented. We consider Zn-doped nickel molybdate (NiMoO₄) (ZNM) as a core crystal structure and AWO₄ (A = Co or Mg) as a shell surface. Based on the density-functional theory method, the interfacial models of Zn-doped NiMoO₄@AWO₄ (ZNM@AW) core@shell structures are simulated and revealed to undergo surface reconstruction on the (-110) and (-202) surfaces of the AW shells, where the surface degradation of ZNM@MW(-110) is observed. The theoretical simulation is validated against the electrochemical performance of supercapacitor studies. To verify, we synthesize the hierarchical ZNM@AW core@shell semiconductor structured nanocomposites grown on a nickel foam conductive substrate using a facile and green two-step hydrothermal method. The morphology and chemical and electrochemical properties of the hierarchically structured nanocomposites are characterized in detail. The performance of the core@shell is significantly affected by the chosen intrinsic properties of metal oxides and exhibited high performance compared to a single-component system in supercapacitors. The proposed asymmetric device, Zn-doped NiMoO₄@CoWO₄ (ZNM@CW)||activated carbon, exhibits a superior pseudo-capacitance, delivering a high areal capacitance of 0.892 F cm^-2 at a current density of 2 mA cm^-2 and an excellent cycling stability of 96% retention of its initial capacitance after 1000 charge-discharge cycles. These fundamental theoretical and experimental insights with the extent of the surface reconstruction sufficiently explain the storage properties of the studied materials.

Rodlike Cadmium-Incorporated Zinc Tungstate Nanoarchitecture Fabricated by a Facile and Template-Free Strategy as a Photocatalyst for the Effective Degradation of Organic Pollutants in Sewage

Fabricating nanostructures and doping engineering are beneficial to tailor the photocatalytic activity of semiconductor materials, and the semiconducting photocatalysis is deemed to be one of the potential protocols to handle the environmental pollution and energy crisis issues. Herein, rodlike Cd-doped ZnWO4 Zn1-x Cd x WO4 nanoarchitectures were triumphantly prepared by a template-free strategy. The crystal structure, chemical state, optical, and photocatalytic features of the Zn1-x Cd x WO4 nanoarchitectures were studied using a variety of characterizations. The Zn1-x Cd x WO4 nanoarchitectures exhibit glorious photocatalytic performance compared with pristine ZnWO4 for the degradation of methyl orange in sewage. Mechanistic studies were executed for getting insights into the photocatalytic degradation process, and the remarkable photocatalytic property of the doped ZnWO4 nanoarchitectures is attributed to the boosted optical absorptive efficiency and the valid segregation and transmission of photogenerated charge carriers deriving from doping effects. The doped nanoarchitectures of this work have promising applications in the territories such as environment and energy chemistry, and the insight proposed in this work will contribute to develop other functionalized nanoarchitectures.

Advances in Template Prepared Nano-Oxides and their Applications: Polluted Water Treatment, Energy, Sensing and Biomedical Drug Delivery

The nano-oxide materials with special structures prepared by template methods have a good dispersion, regular structures and high specific surface areas. Therefore, in some areas, improved properties are observed than conventional bulk oxide materials. For example, in the treatment of dye wastewater, the treatment efficiency of adsorbents and catalytic materials prepared by template method was about 30 % or even higher than that of conventional samples. This review mainly focuses on the progress of inorganic, organic and biological templates in the preparation of micro- and nano- oxide materials with special morphologies, and the roles of the prepared materials as adsorbents and photocatalysts in dye wastewater treatment. The characteristics and advantages of inorganic, organic and biological template are also summarized. In addition, the applications of template method prepared oxides in the field of sensors, drug carrier, energy materials and other fields are briefly discussed with detailed examples.