ZrO₂ is considered an important semiconductor and a heterogeneous photocatalyst along with its diversified applications in dentistry and ceramics. In the present study, ZrO₂ nanostructures were synthesized by hydrothermal treatment accompanied by calcination at different temperatures, viz. 300–800 °C, using zirconyl chloride octahydrate as a precursor, and pure phytochemical- catechin hydrate as a stabilizing agent. Significant variations in the optical properties viz. absorption spectra, and band gap; and structural properties viz. average particle, and crystallite size of ZrO₂ nanostructures were observed due to variable calcination temperatures. The diffraction studies showed that crystallinity appeared in samples synthesized at or above 400 °C. The lowest average crystallite sizes of ~8.96 nm and ~14.5 nm were obtained for the ZrO₂ synthesized at calcination temperatures of 400 and 500 °C, respectively. The obtained XRD data of ZrO₂ nanostructures were further studied by Rietveld refinement using various space groups viz., Fm-3 m for cubic, P121/c1 for monoclinic, and P42/nmc for tetragonal phases. The refinement illustrated the development of the monoclinic phase of ZrO₂ in major composition, for the samples synthesized at or above 400 °C, with preferred orientations along (011), (111), and (1̅11). Furthermore, the HRTEM data showed the formation of the spherical particles with average particle sizes of ~ 47 nm and ~26 nm, prepared at 500 and 600 °C, respectively. Theoretical studies were also carried out to get a mechanistic understanding of the procedure followed in the synthesis and stability of the zirconia nanoparticles. The prepared ZrO₂ nanostructures were further investigated for their photodegradable capability of tetracycline hydrochloride (TCH) under visible light irradiation. Among all the prepared materials, ZrO₂ prepared at 500 °C exhibited a higher photo-degradation efficiency at 180 min under visible light irradiation.

Graphical Abstract

中文翻译：

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通过水热处理合成难以捉摸的单斜 ZrO2 纳米结构

ZrO ₂被认为是一种重要的半导体和多相光催化剂，以及它在牙科和陶瓷领域的多样化应用。在本研究中，ZrO ₂纳米结构是通过水热处理伴随不同温度下的煅烧合成的，即。300–800 °C，以八水氯氧锆为前体，纯植物化学-儿茶素水合物为稳定剂。光学特性的显着变化即。吸收光谱和带隙；和结构特性即 _{ZrO 2}的平均粒径和微晶尺寸由于不同的煅烧温度，观察到纳米结构。衍射研究表明，在 400 °C 或以上合成的样品中出现结晶。在 400 和 500 °C 的煅烧温度下合成的 ZrO ₂分别获得了~8.96 nm 和~14.5 nm 的最低平均微晶尺寸。获得的 ZrO ₂纳米结构的 XRD 数据通过 Rietveld 精修使用各种空间群进一步研究，即立方相的 Fm-3 m、单斜相的 P121/c1 和四方相的 P42/nmc。细化说明了 ZrO _{2的单斜晶相的发展}在主要成分中，对于在 400 °C 或更高温度下合成的样品，具有沿 (011)、(111) 和 (1̅11) 的优选方向。此外，HRTEM 数据显示分别在 500 和 600 °C 下制备的平均粒径为 ~ 47 nm 和 ~ 26 nm 的球形颗粒的形成。还进行了理论研究，以获得对氧化锆纳米粒子的合成和稳定性所遵循的程序的机械理解。进一步研究制备的 ZrO _{2纳米结构在可见光照射下对四环素盐酸盐 (TCH) 的光降解能力。}在所有制备的材料中，在 500 °C 下制备的 ZrO ₂在可见光照射下 180 分钟时表现出更高的光降解效率。

图形概要