Síntese e caracterização de β-ZnMoO4:xNd3+ obtidos pelo método hidrotérmico convencional

Abstract

Advanced ceramic materials are intensively investigated for applications in various industrial sectors; among these materials, ternary oxides can be mentioned. molybdates are part of this advanced ceramics class, with the chemical formula MMoOx (M = Zn, Ca, Mg, Sr). They are of great importance due to their various applications as photocatalysts, electrodes, luminescent materials, and scintillation detectors. Zinc molybdate has attracted significant attention for being non-toxic and exhibiting excellent optical and electrical performance. Specifically, the photoluminescent and photocatalytic properties are enhanced by adding rare earth elements (TR) in the ZnMoO4 matrix. In this sense, the present work reports and compares the photocatalytic activity of ZnMoO4 doped with different percentages of neodymium (Zn1- xMoO4:xNd3+ with x = 0, 0,11, 0,22 and 0,33 mol %) to remove methylene blue dye from water. The catalysts were synthesized by conventional hydrothermal synthesis at 140ºC for 8 hours. Optical properties were also investigated in order to relate to photocatalytic properties. The hydrothermal method used in this work proved efficient for obtaining ZnMoO4 particles. The XRD patterns, together with the structural refinement, showed the formation of the β-ZnMoO4 phase for all samples, which corresponds to a wolframite-type monoclinic crystal structure. There was no secondary phase formation, indicating that doping was successful. The SEM-FEG micrographs showed an evolution of the morphology of the particles in compliance with the increase in the amount of the dopant (Nd3+), having irregular plate-like shapes. The gap energy of Zn1- xMoO4:xNd3+ ranged from 3,18 eV to 3.14 eV. The photoluminescent results showed that the β-ZnMoO4:xNd3+ sample with X = 0,33 showed the highest photoluminescent intensity. As for the photocatalytic activity after reuse in three cycles, the catalyst proved to be efficient, reaching 98,8% of dye degradation, making the photodegradation process very favorable for application in wastewater.