Cation-induced structural/morphological control of ZnO under alkaline hydrothermal conditions: Influence on photocatalytic activity
This study investigates the hydrothermal synthesis of ZnO nanopowders using three different alkaline reagents: KOH, NaOH, and NH<inf>4</inf>OH, focusing on their morphological, structural, and photocatalytic properties. The resulting ZnO powders displayed distinct morphologies − from hex...
| Autores: | , , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versión aceptada para publicación |
| Data de publicação: | 2025 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositório: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/418905 |
| Acesso em linha: | http://hdl.handle.net/10261/418905 https://api.elsevier.com/content/abstract/scopus_id/105020429143 |
| Access Level: | Acesso embargado |
| Palavra-chave: | Alkaline cations Crystal growth Photocatalysis ZnO nanoparticles |
| Resumo: | This study investigates the hydrothermal synthesis of ZnO nanopowders using three different alkaline reagents: KOH, NaOH, and NH<inf>4</inf>OH, focusing on their morphological, structural, and photocatalytic properties. The resulting ZnO powders displayed distinct morphologies − from hexagonal rods and prismatic structures to a 3D butterfly-nebula-like morphology − depending on the base employed. Phase purity and structural characteristics were confirmed via X-ray diffraction (XRD) and Raman spectroscopy, while scanning and transmission electron microscopy (SEM/TEM) revealed significant morphological differences at multiple magnifications. When hydrothermally produced using KOH and NaOH, ZnO crystallizes into hexagonal prismatic rods along the [0001] direction, starting from a zinc hydroxide precipitate. However, its transition to Zn ammine complex occurs by replacing K<sup>+</sup>or Na<sup>+</sup>with NH<inf>4</inf><sup>+</sup>ions during hydrothermal reaction, which changes the preferential crystal growth, favoring the lateral direction. As a result, ZnO nanostructures with a 3D butterfly-nebula-like morphology are formed. This alteration influences the photocatalytic activity, which is assessed by monitoring the degradation of Reactive Orange 16 (RO16) dye under UV irradiation. The ZnO nanopowder synthesized using NaOH exhibited the highest photocatalytic efficiency, achieving complete degradation of the dye within 90 min. The sample prepared with KOH showed a faster degradation rate than the one synthesized with NH<inf>4</inf>OH, but still lower than that of the NaOH-based sample. These findings highlight the crucial influence of base selection during hydrothermal synthesis on the morphology, crystallite size, and photocatalytic behavior of ZnO nanostructures, providing insights for the design of more efficient materials for environmental remediation applications. |
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