Nanocrystalline CaWO4 and ZnWO4 Tungstates for Hybrid Organic-Inorganic X-ray Detectors

Hybrid materials combining an organic matrix and high-Z nanomaterials show potential for applications in radiation detection, allowing unprecedented device architectures and functionality. Herein, novel hybrid organic-inorganic systems were produced using a mixture of tungstate (CaWO4 or ZnWO4) nanoparticles with a P3HT:PCBM blend. The nano-tungstates with a crystallite size of 43 nm for CaWO4 and 30 nm for ZnWO4 were synthesized by the hydrothermal method. Their structure and morphology were characterized by X-ray diffraction and scanning electron microscopy. The hybrid systems were used to fabricate direct conversion X-ray detectors able to operate with zero bias voltage. The detector performance was tested in a wide energy range using monochromatic synchrotron radiation. The addition of nanoparticles with high-Z elements improved the detector response to X-ray radiation compared with that of a pure organic P3HT:PCBM bulk heterojunction cell. The high dynamic range of our detector allows for recording X-ray absorption spectra, including the fine X-ray absorption structure located beyond the absorption edge. The obtained results suggest that nanocrystalline tungstates are promising candidates for application in direct organic-inorganic X-ray detectors.

A novel electrochemical sensor for the detection of enrofloxacin based on a 3D flower-like metal tungstate-incorporated reduced graphene oxide nanocomposite

In recent times, metal tungstates have received a lot of attention in various research fields. Accordingly, the CaWO₄/RGO (CW/RGO) nanocomposite was prepared by a facile hydrothermal method. The electrocatalytic performance of the hydrothermally prepared CW/RGO nanocomposite was used for the electrochemical detection of the antibiotic medicine enrofloxacin (ENF). The electrocatalytic oxidation performance of ENF was examined by cyclic voltammetry (CV) and amperometry (AMP) techniques. The CV results showed the lowest anodic peak potential and the enhanced anodic peak current response compared to the other modified electrodes. Mainly, our newly proposed sensor exhibited excellent electrochemical performance with the lowest limit of detection (LOD) of 0.021 μM, and a significant linear range of 0.001-115 μM. Additionally, our proposed sensor exhibited good selectivity, great long-term stability, and excellent reproducibility. Then, our proposed sensor was successfully applied to detect the amount of ENF in a milk sample and river water, which exhibited good satisfactory results.

Salt-assisted size-controlled synthesis and luminescence studies of single phase CaWO4:Dy3+: an insight into its morphological evolution, energy transfer and colour evaluation

The size of the particles of CaWO₄:Dy³⁺ increases with the addition of NH₄Cl/KCl electrolyte and enhances its luminescence.

Nanostructured Ternary Metal Tungstate-Based Photocatalysts for Environmental Purification and Solar Water Splitting: A Review

Visible-light-responsive ternary metal tungstate (MWO₄) photocatalysts are being increasingly investigated for energy conversion and environmental purification applications owing to their striking features, including low cost, eco-friendliness, and high stability under acidic and oxidative conditions. However, rapid recombination of photoinduced electron-hole pairs and a narrow light response range to the solar spectrum lead to low photocatalytic activity of MWO₄-based materials, thus significantly hampering their wide usage in practice. To enable their widespread practical usage, significant efforts have been devoted, by developing new concepts and innovative strategies. In this review, we aim to provide an integrated overview of the fundamentals and recent progress of MWO₄-based photocatalysts. Furthermore, different strategies, including morphological control, surface modification, heteroatom doping, and heterojunction fabrication, which are employed to promote the photocatalytic activities of MWO₄-based materials, are systematically summarized and discussed. Finally, existing challenges and a future perspective are also provided to shed light on the development of highly efficient MWO₄-based photocatalysts.

Upconversion luminescence of lanthanide-doped mixed CaMoO4–CaWO4 micro-/nano-materials

The synthesis and characterization of Er³⁺,Yb³⁺ doped mixed CaMoO₄–CaWO₄ micro-/nano-upconversion materials is presented in this paper. The relative intensities of the green and red emission bands can be enhanced by heat treatment or through Gd³⁺ co-doping.

Controllable synthesis of uniform CaMoO4:Eu3+,M+ (M = Li, Na, K) microspheres and optimum luminescence properties

High-quality and monodisperse CaMoO₄:Eu³⁺,M⁺ (M = Li, Na, K) microspheres have been synthesized with the assistance of poly-(diallyldimethylammonium chloride) (PDDA) via a facile coprecipitation hydrothermal route.

Self-assembled 3D sphere-like SrMoO4 and SrMoO4:Ln3+ (Ln=Eu, Sm, Tb, Dy) microarchitectures: facile sonochemical synthesis and optical properties

Three-dimensional (3D) well-defined SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures of obvious sphere-like shape have been successfully synthesized using a large-scale and facile sonochemical route without using any catalysts or templates. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of SrMoO4 and external factor, namely the ultrasonic time and the pH value, are responsible for the ultimate shape evolutions of the product. The possible formation mechanism for the product is presented. Additionally, the PL properties of SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures were investigated in detail. The Ln(3+) ions doped SrMoO4 samples exhibit respective bright red-orange, yellow, green and white light of Eu(3+), Sm(3+), Tb(3+) and Dy(3+) under ultraviolet excitation, and have potential application in the field of color display. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating about the properties of molybdate materials.