Abstract

Heterogeneous photocatalytic (PC) degradation of organic dyes in aqueous solution with semiconductor oxides has been very effective in relation to conventional methods for the wastewater treatment. In this paper, MgWO₄ powder was synthesized by the complex polymerization method and heat-treated at 900 °C for 2 h. Their structure, morphology and optical behavior were characterized by different techniques. First-principles quantum mechanical calculations based on the DFT in the B3LYP level was employed to obtain their electronic band structure (EBS) and density of state (DOS). Moreover, we have investigated the PC properties for the discoloration of three organic dyes. XRD patterns indicate that MgWO₄ powders present a monoclinic structure. FE-SEM and TEM images showed that these powders are composed of several nanoparticles. UV–Vis spectrum displays an optical band gap of 4.33 eV, while EBS calculation showed a direct band gap value of 4.49 eV. DOS data revealed that the main orbitals involved in the electronic structure are O-2p orbitals in the valence band and W-5d orbitals in the conduction band. Finally, it was obtained the best PC activity of MgWO₄ powders with discoloration of 84% for bromocresol green dye, while the discoloration for methyl orange and rhodamine B dyes were 56% and 29%, respectively.

Graphic Abstract

The electronic structure, morphology and photocatalytic properties of MgWO₄ powders synthesized by complex polymerization method calcinated at 900 °C for 2 h have been explained for the first time.

中文翻译：

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复杂聚合法合成MgWO 4粉末对三种有机染料的电子结构，形态学特征和光催化褪色

摘要

与用于废水处理的常规方法相比，具有半导体氧化物的水溶液中有机染料的多相光催化（PC）降解非常有效。本文采用复合聚合法合成了MgWO ₄粉末，并在900℃下热处理2h。通过不同的技术表征了它们的结构，形态和光学行为。利用基于B3LYP能级的DFT的第一性原理量子力学计算来获得其电子能带结构（EBS）和状态密度（DOS）。此外，我们研究了PC性能，用于三种有机染料的脱色。XRD图谱表明MgWO ₄粉末呈现单斜晶结构。FE-SEM和TEM图像显示这些粉末由几种纳米颗粒组成。UV-Vis光谱显示的光学带隙为4.33 eV，而EBS计算的直接带隙值为4.49 eV。DOS数据显示，电子结构中涉及的主要轨道是价带中的O-2 p轨道和导带中的W-5 d轨道。最后，获得了最佳的PC活性，MgWO ₄粉末对溴甲酚绿染料的变色率为84％，而甲基橙和若丹明B染料的变色分别为56％和29％。

图形摘要

首次阐述了在900°C下煅烧2 h的复合聚合法合成的MgWO ₄粉末的电子结构，形貌和光催化性能。