Cerium-based adsorbents are effective for the removal of phosphate from water, with the reactivity of cerium dioxide (CeO₂) being highly dependent on the exposed crystal facets. However, molecular-level interactions that control the facet-dependent reactivity toward phosphate adsorption remain elusive. In this study, we synthesized CeO₂ nanostructures with distinct morphologies─rods (CeO₂-R), octahedrons (CeO₂-O), and cubes (CeO₂-C)─that predominantly expose the (110), (111), and (100) crystal facets, respectively. Phosphate adsorption on various CeO₂ facets was systematically investigated through a series of batch adsorption experiments, complemented by Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations. The phosphate adsorption follows second-order kinetics and aligns with the Langmuir isotherm model. This process is facilitated by the formation of inner-sphere complexes between the Ce–OH groups on the CeO₂ surface and the phosphate ions. The adsorption performance is significantly influenced by the geometric configuration of the exposed CeO₂ facets, with the normalized phosphate adsorption capacity to surface area following the trend of CeO₂-R > CeO₂-C > CeO₂-O. These results may have strong implications for prediction of the fate of contaminants at the solid–liquid interface and optimization of advanced adsorbent materials for water treatment applications.

中文翻译：

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CeO2 的刻面依赖性磷酸盐吸附


铈基吸附剂可有效去除水中的磷酸盐，二氧化铈 （CeO₂） 的反应性高度依赖于暴露的晶体刻面。然而，控制对磷酸盐吸附的刻面依赖性反应性的分子水平相互作用仍然难以捉摸。在这项研究中，我们合成了具有不同形态的 CeO₂ 纳米结构——棒 （CeO_2-R）、八面体 （CeO_2-O） 和立方体 （CeO_2-C），分别主要暴露 （110）、（111） 和 （100） 晶体刻面。通过一系列批量吸附实验，辅以傅里叶变换红外 （FTIR） 光谱和密度泛函理论 （DFT） 计算，系统研究了 CeO₂ 各个面上的磷酸盐吸附。磷酸盐吸附遵循二阶动力学，并与 Langmuir 等温线模型一致。CeO₂ 表面的 Ce-OH 基团与磷酸根离子之间形成的内球络合物促进了这一过程。吸附性能受暴露的 CeO₂ 刻面的几何构型的显著影响，磷酸盐对表面积的归一化吸附能力遵循 CeO_2-R > CeO_2-C > CeO_2-O 的趋势。这些结果可能对预测固液界面处污染物的归宿以及优化用于水处理应用的先进吸附剂材料具有重要意义。