Facet-dependent dual active sites of CeO2 govern distinct adsorption mechanisms for fluorinated organics and inorganic fluoride
image: The facet-dependent dual active-site mechanisms governing CeO2 interactions with fluorine-bearing contaminants Lewis acid sites govern the affinity of CeO2 toward organic fluorine species, in sharp contrast to the hydroxyl/OV-controlled mechanisms dominating inorganic F⁻ uptake.
Credit: Nano Research, Tsinghua University Press
Fluorine-containing contaminants pose a growing challenge for water treatment. Inorganic fluoride (F⁻) can threaten public health at elevated concentrations, while per- and polyfluoroalkyl substances (PFAS)—often called “forever chemicals”—are difficult to remove because their carbon–fluorine bonds resist breakdown. Conventional approaches frequently struggle with either selectivity (for fluoride) or affinity and mass transfer (for PFAS), underscoring the need for materials whose surface chemistry is intrinsically tuned for fluorinated species. CeO2-based materials have shown great promise in both adsorption and catalytic degradation applications. Nevertheless, most existing studies address either inorganic fluoride or PFAS separately, ignoring the frequent coexistence of the two in natural and engineered environments, and the fundamental distinctions in their interfacial affinity and reaction mechanisms on CeO2 remain largely unexplored, leaving a critical gap in understanding the selective remediation strategies for fluoride pollution by CeO2-based materials.
A research team led by Zhongying Wang at Southern University of Science and Technology has now shown that the facet-dependent dual active-site mechanisms governing CeO2 interactions with fluorine-bearing contaminants. The researchers synthesized facet-controlled CeO2 nanocrystals exposing dominant (111), (110), and (100) facets, respectively, to distinguish the affinity mechanisms toward PFOA and F⁻.
The team published their study in Nano Research on March 27, 2026.
In this adsorption tests, the (111)-faceted Oct removed 100% of PFOA within 24 hours, outperforming (110)-faceted Rod and (100)-faceted Cube, and reached a maximum adsorption capacity of 100.6 mg/g. For fluoride, the trend reversed: the (110)-faceted Rod achieved the highest uptake, with a maximum capacity of 178.9 mg/g.
Integrated spectroscopic analyses, quenching tests, and DFT calculations revealed that surface hydroxyl groups and oxygen vacancies dominated F⁻ adsorption through ion exchange and vacancy filling, whereas unsaturated Ce(IV) Lewis acid sites controlled PFOA adsorption via C–F bond polarization and lattice oxygen substitution. Pyridine-IR quantification and phosphate inhibition experiments confirmed a direct correlation between Lewis acidity and organic fluorine affinity. DFT results further demonstrated that the (111) facet possesses the strongest Lewis acidity and charge-transfer ability, while the (110) facet favors hydroxylation and fluoride binding.
“This work provides a clear structure–facet–function relationship for ceria in fluorine capture,” Wang said. “By choosing the dominant facet, we can bias the surface toward the active sites that matter most for either inorganic fluoride or fluorinated organics, which helps rationalize why the same oxide can behave so differently across pollutants.”
The researchers expect the findings to inform the design of next-generation fluorine-selective adsorbents and catalytic platforms. Because Ce is also widely used in catalysis, facet-guided tuning of Lewis acidity, hydroxylation, and oxygen vacancies may help connect efficient capture with downstream destruction of PFAS—an important step toward practical treatment strategies.
Other contributors include Youmei Xu, Beizhao Chen, Aling Wan, Weiwen Chen, Chaoqun Zhu, Shidong Zheng, and Zhipeng Liu from the School of Environmental Science and Engineering at Southern University of Science and Technology in Shenzhen, China.
This work was supported by the National Natural Science Foundation of China (No. 22476079), the Key Program of Fundamental Research funded by the Shenzhen Science and Technology Innovation Commission (JCYJ20220818100218039), and the Guangdong Major Project of Basic and Applied Basic Research (2023B0303000024). This work was also supported by the State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control. The authors also acknowledge the assistance of SUSTech Core Research Facilities.
DOI Link:
https://doi.org/10.26599/NR.2026.94908404
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.