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Preparation of Yb-doped ZnO nanoparticles by combustion method combined with high temperature calcination for photodegradation of methylene blue under visible light irradiation

About: This article is published in Materials Research Innovations.The article was published on 2021-09-23. It has received 2 citations till now. The article focuses on the topics: Photodegradation & Calcination.
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Journal ArticleDOI
TL;DR: The proposed photocatalyst can efficiently and rapidly degrade azo dyes and can be applied to the treatment of wastewater contaminated with synthetic dyes, which is economical and environment-friendly.
Abstract: Zinc oxide (ZnO) photocatalysts were synthesized by sol–gel method using zinc acetate as precursor for degradation of azo dyes under UV irradiation. The resultant samples were characterized by different techniques, such as XRD, SEM, and EDX. The influence of preparation conditions such as calcination temperature and composite ratio on the degradation of methyl orange (MO) was investigated. ZnO prepared with a composite ratio of 4:1 and calcination temperature of 400 °C exhibited 99.70% removal rate for MO. The effect of operation parameters on the degradation was also studied. Results showed that the removal rate of azo dyes increased with the increased dosage of catalyst and decreased initial concentration of azo dyes and the acidic condition is favorable for degradation. Furthermore, the kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of azo dyes fitted the first-order kinetics and superoxide ions were the main species. The proposed photocatalyst can efficiently and rapidly degrade azo dyes; thus, this economical and environment-friendly photocatalyst can be applied to the treatment of wastewater contaminated with synthetic dyes.

461 citations

Journal ArticleDOI
TL;DR: A qualitative as well as quantitative spectroscopic study of methylene blue aggregation that occurs upon freezing the aqueous solutions over a wide concentration range, helping to understand how the initial conditions control the course of the process.
Abstract: The paper presents a qualitative as well as quantitative spectroscopic study of methylene blue (MB) aggregation that occurs upon freezing the aqueous solutions over a wide concentration range. The Gaussian curve analysis and the multivariate curve resolution-alternating least squares method were used to determine the number and concentration of chemical species responsible for the overlaying absorption visible spectra measured. The results show the extent of aggregation for the concentrations above 10(-7) mol L(-1), being dependent on the freezing rate and the initial concentration. While the local concentration of MB at the grain boundaries of polycrystalline ice increased by approximately 3 orders of magnitude upon fast freezing at 77 K compared to the liquid phase, the concentration raised at least by 6 orders of magnitude upon slow freezing at 243 K. Since enhancement of the local concentration of solutes plays an important role in (photo)chemical transformations in solid aqueous media, this work helps to understand how the initial conditions control the course of the process. The results are relevant in other interdisciplinary fields, such as environmental chemistry, cosmochemistry, or geochemistry.

263 citations

Journal ArticleDOI
TL;DR: This work illustrates an effective and facile route toward modifying and optimizing optical properties of double perovskite Cs2AgBiX6 (X = Cl-, Br-) NCs with an indirect bandgap nature, which can broaden a range of their potential applications in optoelectronic devices.
Abstract: Lead-free double perovskite nanocrystals (NCs) have emerged as a new category of materials that hold the potential for overcoming the instability and toxicity issues of lead-based counterparts. Doping chemistry represents a unique avenue toward tuning and optimizing the intrinsic optical and electronic properties of semiconductor materials. In this study, we report the first example of doping Yb3+ ions into lead-free double perovskite Cs2AgBiX6 (X = Cl-, Br-) NCs via a hot injection method. The doping of Yb3+ endows the double perovskite NCs with a newly emerged near-infrared emission band (sensitized from the NC hosts) in addition to their intrinsic trap-related visible photoluminescence. By controlling the Yb-doping concentration, the dual emission profiles and photon relaxation dynamics of the double perovskite NCs can be systematically tuned. Furthermore, we have successfully inserted divalent Mn2+ ions in Cs2AgBiCl6 NCs and observed emergence of dopant emission. Our work illustrates an effective and facile route toward modifying and optimizing optical properties of double perovskite Cs2AgBiX6 (X = Cl-, Br-) NCs with an indirect bandgap nature, which can broaden a range of their potential applications in optoelectronic devices.

171 citations

Journal ArticleDOI
TL;DR: The results show that Se doping significantly improves the photocatalytic activity of TiO2 and 13.63 at.% Se-dopedTiO2 has the best performance.
Abstract: Anatase TiO2 is a typical photocatalyst, and its excellent performance is limited in ultraviolet light range due to its wide band gap of 3.2 eV. A series of Se-doped TiO2 nanoparticles in anatase structure with various Se concentrations up to 17.1 at.% were prepared using sol-gel method. The doped Se ions are confirmed to be mainly in the valence state of + 4, which provides extra electronic states in the band gap of TiO2. The band gap is effectively narrowed with the smallest gap energy of 2.17 eV, and the photocatalytic activity is effectively improved due to the extended absorption range. The photocatalytic activity was evaluated by the degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation. The results show that Se doping significantly improves the photocatalytic activity of TiO2 and 13.63 at.% Se-doped TiO2 has the best performance.

155 citations

Journal ArticleDOI
TL;DR: Visible light-driven photocatalysts of lanthanum (La) doped ZnO nanoparticles were successfully prepared by a facile precipitation method using various La doping concentrations (0.5, 1.0 and 1.5) as discussed by the authors.

133 citations