RESUMEN
The WO3 and WO3:Pr3+ particles were successfully synthesized by the co-precipitation method. The XRD analysis with Rietveld refinement revealed the formation of a monoclinic phase for WO3 and for doped samples, this result was later confirmed by Raman spectroscopy studies. The presence of Pr3+ in the WO3 crystalline lattice induced structural and optical changes in the particles, increasing the crystallite size, distorting the clusters (shortening of the W-O bonds), favoring the crystallinity and changing the optical gap. The predominant morphology of the particles of WO3 and WO3:Pr3+ obtained was nanocubes constituted by the superposition of plates of nanometric thicknesses. The photoluminescence of WO3 and WO3:Pr3+ was produced by the existence of surface defects in the particles. The increase in the concentration of Pr3+ promoted an increase in the intensity of PL, due to the increase in the rate of recombination of electron/hole charges. The WO3 sample exhibited emission in the white region due to the adjustment of simultaneous electronic transitions in the blue, green and red regions, characteristic of the broadband spectrum. The interval of the 2.65 eV gap band and the high efficiency in the separation of the photogenerated charges (e-/h+) with the low recombination rate contributed to the photocatalytic degradation of Crystal Violet (CV) by the catalyst. The WO3:4% Pr3+ sample showed the best photocatalytic efficiency, degrading 73% of the CV dye in 80 minutes. This result was associated with a reduction in particle size and density of oxygen vacancies on the material surface.
RESUMEN
This study consists of the synthesis of zinc-doped Bi2WO6 obtained by the sonochemical method. The XRD results indicated that the samples showed an orthorhombic phase with the P21ab space group without the presence of secondary phases, demonstrating success in the doping process. The results of the photocatalytic tests under the photodegradation of methylene blue showed better performance for the pure sample with 80% degradation during 2 hours of exposure to radiation. The high rate of photogenerated charges accompanied by the low recombination rate of the pairs and e-/h+ were responsible for forming hydroxyl radicals, the predominant oxidative agent of the mechanism. The increase in Zn2+ concentration in the Bi2WO6 matrix promoted inhibition of the photocatalytic properties by the appearance of oxygen vacancies that acted as a charge recombination center. In contrast, photoluminescence was improved by doping with Zn2+. The Bi2WO6:8% Zn2+ sample showed the highest PL intensity. The characteristics of the emitted colors are modulated from the emission spectra and are quantified in terms of the photometric parameters: chromaticity coordinates (x, y), color reproduction index (CRI), luminous radiation efficiency (LER), and purity of color (%) of samples. The adjustment in the colors is promoted as a function of the increase in the Zn2+ concentration observing the transition from: yellow â orange â green. PL is favored by the effect of the dopant (Zn2+) in the matrix, which allows Bi2WO6:Zn2+ to be considered a promising candidate for applications in optical devices. In addition, Bi2WO6 constitutes a high performance photocatalyst for the degradation of methylene blue.
RESUMEN
Correction for 'Synthesis and evaluation of photocatalytic and photoluminescent properties of Zn2+-doped Bi2WO6' by L. X. Lovisa, et al., Dalton Trans., 2022, https://doi.org/10.1039/d2dt03175b.
RESUMEN
In the present work, Sr0.9-x-y-zCa0.1In2O4:(xEu3+, yTm3+, zTb3+) particles were synthesized by the ultrasonic spray pyrolysis (USP) method to obtain a single-phase white phosphorus formed by six different cations in solution within the lattice (superstructure). The samples were also structurally and morphologically characterized by X-ray diffraction (XRD) techniques and by field emission scanning electron microscopy (FE-SEM). The photoluminescent behavior and the characteristics of the emitted colors were studied by the variation in the co-doping of the rare earth elements. The Sr0.9Ca0.1In2O4 sample showed a near blue color emission, but all co-doped samples showed emission in white with very close chromaticity coordinates to the standard white (xâ¯=â¯0.33 and yâ¯=â¯0.33). The Tm3+â¯ââ¯Tb3+ (ET1), Tm3+â¯ââ¯Eu3+ (ET2) and Tb3+â¯ââ¯Eu3+ (ET3) Energy Transfers were proposed and are considered necessary for adjusting and controlling the desired color properties.
