Konyuhova, Anastasiya Dmitrievna

Plakhova T.V., Romanchuk A.Y., Konyukhova A.D., Seregina I.F., Baranchikov A.E., Svetogorov R.D., Terban M.W., Ivanov V.K., Kalmykov S.N.

CeO2 surface is crucial for dissolution process. Untreated nanoparticles are more soluble than dried ones due to their hydrated state. Dried CeO2 solubility increases as the surface returns to a hydrated state, ensuring long-term stability.

Romanchuk A.Y., Plakhova T.V., Konyukhova A.D., Smirnova A., Kozlov D.A., Novichkov D.A., Trigub A.L., Kalmykov S.N.

Plakhova T.V., Romanchuk A.Y., Butorin S.M., Konyukhova A.D., Egorov A.V., Shiryaev A.A., Baranchikov A.E., Dorovatovskii P.V., Huthwelker T., Gerber E., Bauters S., Sozarukova M.M., Scheinost A.C., Ivanov V.K., Kalmykov S.N., et. al.

Understanding the complex chemistry of functional nanomaterials is of fundamental importance. Controlled synthesis and characterization at the atomic level is essential to gain deeper insight into the unique chemical reactivity exhibited by many nanomaterials. Cerium oxide nanoparticles have many industrial and commercial applications, resulting from very strong catalytic, pro- and anti-oxidant activity. However, the identity of the active species and the chemical mechanisms imparted by nanoceria remain elusive, impeding the further development of new applications. Here, we explore the behavior of cerium oxide nanoparticles of different sizes at different temperatures and trace the electronic structure changes by state-of-the-art soft and hard X-ray experiments combined with computational methods. We confirm the absence of the Ce(iii) oxidation state at the surface of CeO2 nanoparticles, even for particles as small as 2 nm. Synchrotron X-ray absorption experiments at Ce L3 and M5 edges, combined with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and small angle X-ray scattering (SAXS) and theoretical calculations demonstrate that in addition to the nanoceria charge stability, the formation of hydroxyl groups at the surface profoundly affects the chemical performance of these nanomaterials.

Liu B., Pan Y., Han Z., Shu Y., Liu X., Zhang M., Wan A., Wang M., Tan Y., Wang Z.

Ta K.M., Neal C.J., Coathup M., Seal S., Phillips R.M., Molinari M.

Liu Y., Wu P., Chen M., Wang T., Sun L., Lu B., Zhu N., Dang Z.

The widespread mining and application of rare earth elements (REEs) have led to their continuous accumulation in the environment, with increasing concentrations in soil. The interaction between the most abundant REEs, cerium (Ce), and the prevalent hexagonal birnessite (HB) in the environment is worth attention. HB is one of the most effective metal oxides for the oxidation of arsenite [As(III)] and subsequent adsorption, and thus for arsenic (As) immobilization. Therefore, in this study, we investigated the effect of the presence of Ce(III) ion on the HB formation process and the influence of generating minerals on the oxidation and removal of As(III). Research has found that the interfacial reactions of REEs in manganese (Mn) minerals not only affect their cycling but also alter the properties of the Mn minerals, thereby affecting the environmental fate of As. The results indicated that the presence of Ce ions affected the structure of HB during mineral synthesis and reduced the crystallinity of the conversion products. Their substitution for Mn(IV) in the lattice increased the specific surface area of minerals, reduced particle size, and produced more hydroxyl groups that were conducive to the immobilization of As(III). Meanwhile, Ce(III) was oxidized to Ce(IV) during the formation of Ce-bearing hexagonal birnessite (Ce-HB), and CeO

Plakhova T.V., Vyshegorodtseva M.A., Seregina I.F., Svetogorov R.D., Trigub A.L., Kozlov D.A., Egorov A.V., Shaulskaya M.D., Tsymbarenko D.M., Romanchuk A.Y., Ivanov V.K., Kalmykov S.N.

El Komy G.M., Nasralla N.H., El-Bassyouni G.T., Mousa S.M.

Kvashnina K.

AbstractHistorically, cerium has been attractive for pharmaceutical and industrial applications. The cerium atom has the unique ability to cycle between two chemical states (Ce(III) and Ce(IV)) and drastically adjust its electronic configuration: [Xe] 4f15d16s2 in response to a chemical reaction. Understanding how electrons drive chemical reactions is an important topic. The most direct way of probing the chemical and electronic structure of materials is by X‐ray absorption spectroscopy (XAS) or X‐ray absorption near‐edge structure (XANES) in high energy resolution fluorescence detection (HERFD) mode. Such measurements at the Ce L3 edge have the advantage of a high penetration depth, enabling in‐situ reaction studies in a time‐resolved manner and investigation of material production or material performance under specific conditions. But how much do we understand Ce L3 XANES? This article provides an overview of the information that can be extracted from experimental Ce L3 XAS/XANES/HERFD data. A collection of XANES data recorded on various cerium systems in HERFD mode is presented here together with detailed discussions on data analysis and the current status of spectral interpretation, including electronic structure calculations.

Thomas E., Briançon S., Chaput F., Magnano G.C., Trenque I., Arquier D., Barratier C., Amans D., Devers T., Pitault I., Masenelli-Varlot K., Bugnet M., Bolzinger M.

Plakhova T.V., Romanchuk A.Y., Konyukhova A.D., Seregina I.F., Baranchikov A.E., Svetogorov R.D., Terban M.W., Ivanov V.K., Kalmykov S.N.

CeO2 surface is crucial for dissolution process. Untreated nanoparticles are more soluble than dried ones due to their hydrated state. Dried CeO2 solubility increases as the surface returns to a hydrated state, ensuring long-term stability.

Cladek B., Zhang Y., Maier R., Ravel B., Tucker M.G., Levin I.

This study considers critical data reduction steps and data analysis approaches required to determine explicitly the atomic arrangements in nanoparticles from time-of-flight neutron total scattering. A practical procedure is described for removing parasitic backgrounds caused by the incoherent scattering of hydrogen inevitably present in most nanoparticle samples and normalizing the recovered coherent scattering intensities onto an absolute scale. A model-free analysis is presented of a pair-distribution function derived from total scattering that can be used to determine thermal expansion coefficients and particle sizes directly from experimental data without knowledge of the material's structure. Finally, atomistic whole-nanoparticle refinements of yttrium-doped ceria nanoparticles from neutron total-scattering data are demonstrated using the reverse Monte Carlo method implemented in the RMCProfile software. These results reveal a strong dependence of the cation–oxygen and oxygen–oxygen distances on the coordination numbers, which leads to gradients of these distances near the particle surface. The details are dependent on the surface coverage by ligands and adsorbates and on the structure of grain boundaries in nanocrystalline agglomerates. The refined models confirm the expectations of more substantial disorder at particle surfaces, with a distorted surface layer extending over several coordination shells. The results highlight the feasibility of whole-nanoparticle refinements from neutron data, calling for further development of data reduction and analysis procedures.

Murphy G.L., Bazarkina E., Svitlyk V., Rossberg A., Potts S., Hennig C., Henkes M., Kvashnina K.O., Huittinen N.

Ma M., Ke X., Wang T., Li J., Ye H.

Electrolytic manganese slag (EMS), a bulk waste generated in industrial electrolytic manganese production, can be a cost-effective adsorbent for heavy metals removal after appropriate modification. In this study, EMS was activated by NaOH and then used to make the EMS-based double-network hydrogel (an EMS/PAA hydrogel) via a one-pot method. The results showed that the EMS/PAA hydrogel exhibits a high selective adsorption capacity of 153.85, 113.63 and 54.35 mg·g-1 for Pb (II), Cd (II) and Cu (II), respectively. In addition, Density Functional Theory (DFT) suggests that the adsorption energies (Ead) of Pb, Cd and Cu on SiO2/PAA of the EMS/PAA gels are - 4.15, - 1.96, and - 2.83 eV, respectively, and SiO2/PAA, with a strong affinity to Pb2+, is one of the reasons for the selective adsorption capacity of EMS/PAA gel for Pb2+. The removal efficiency of the EMS/PAA gel for Pb2+, Cd2+, Cu2+ decreased after four adsorption-desorption cycles by 20.00 %, 24.56 % and 46.56 %, respectively. Mechanism studies suggested that the elimination of the heavy metals by EMS/PAA gels mainly involves electrostatic attraction, inner-sphere complexation, and coordination interactions. The EMS/PAA hydrogels not only have high adsorption capacity, but are also easy to prepare and circulate, making them ideal for practical applications.

Isaeva E.I., Sizova A.A., Boitsova T.B., Staritsyn M.V., Fedoseev M.L.

Two methods for preparing mesoporous CeO2/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, morphology of the obtained nanocomposites, as well as the specific surface area and pore size distribution were studied by a complex of physicochemical methods: X-ray phase analysis, X-ray spectral microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electron spectroscopy. The catalytic properties of the obtained nanocomposites were studied in methyl orange photodegradation reactions. It is shown that the CeO2/Au catalyst obtained by the photochemical modification method has the highest photocatalytic activity both under the action of UV and visible light.

Isaeva E.I., Sizova A.A., Boitsova T.B., Staritsyn M.V., Fedoseev M.L.

Two methods for preparing mesoporous CeO2/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, and morphology, as well as the specific surface area and the pore size distribution of the obtained nanocomposites were studied by a set of physicochemical methods: X-ray phase analysis, energy dispersive X-ray microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electronic spectroscopy. The catalytic properties of the synthesized nanocomposites were evaluated in the methyl orange photodegradation reactions. It was shown that the CeO2/Au catalyst prepared by the photochemical modification method has the highest photocatalytic activity under exposure to both UV and visible light.

Il’in E.G., Parshakov A.S., Iskhakova L.D., Kottsov S.Y., Filippova A.D., Goeva L.V., Simonenko N.P., Baranchikov A.E., Ivanov V.K.

The behavior of cerium tetrafluoride hydrate was studied in water at a temperature of 80°C and under hydrothermal treatment at 100, 130, and 220°C for a day. The product of the hydrothermal treatment of CeF4·H2O at 100°C was investigated by chemical, thermogravimetric, IR spectroscopic, and X-ray powder diffraction analyses, which identified a new cerium fluoride with the composition, presumably, Ce3F10⋅3H2O or, most likely, (H3O)Ce3F10⋅2H2O. New compound crystallizes in the space group $$Fm\bar {3}m$$ with a unit cell parameter of 11.66 Å. Hydrothermal treatment of cerium tetrafluoride hydrate at temperatures above 130°C leads to hydrolysis and reduction of cerium(IV) fluoride compounds to form CeO2 and CeF3.

Baranchikov A.E., Sozarukova M., Mikheev I.V., Egorova A., Proskurnina E., Poimenova I., Krasnova S., Filippova A.D., Ivanov V.

The diversity of catalytic activities and antioxidant properties of cerium oxide nanoparticles (CeO2 NPs) makes them promising materials for the theranostics of various diseases, especially those caused by disturbances in...

Estevenon P., Amidani L., Bauters S., Tamain C., Bodensteiner M., Meurer F., Hennig C., Vaughan G., Dumas T., Kvashnina K.O.

Kiefer C., Neill T., Cevirim-Papaioannou N., Schild D., Gaona X., Vitova T., Dardenne K., Rothe J., Altmaier M., Geckeis H.

The impact of temperature on a freshly precipitated ThO2(am, hyd) solid phase was investigated using a combination of undersaturation solubility experiments and a multi-method approach for the characterization of the solid phase. XRD and EXAFS confirm that ageing of ThO2(am, hyd) at T = 80°C promotes a significant increase of the particle size and crystallinity. TG-DTA and XPS support that the ageing process is accompanied by an important decrease in the number of hydration waters/hydroxide groups in the original amorphous Th(IV) hydrous oxide. However, while clear differences between the structure of freshly precipitated ThO2(am, hyd) and aged samples were observed, the characterization methods used in this work are unable to resolve clear differences between solid phases aged for different time periods or at different pH values. Solubility experiments conducted at T = 22°C with fresh and aged Th(IV) solid phases show a systematic decrease in the solubility of the solid phases aged at T = 80°C. In contrast to the observations gained by solid phase characterization, the ageing time and ageing pH significantly affect the solubility measured at T = 22°C. These observations can be consistently explained considering a solubility control by the outermost surface of the ThO2(s, hyd) solid, which cannot be properly probed by any of the techniques considered in this work. Solubility data are used to derive the thermodynamic properties (log *K°s,0, ΔfG°m) of the investigated solid phases, and discussed in terms of particle size using the Schindler equation. These results provide new insights on the interlink between solubility, structure, surface and thermodynamics in the ThO2(s, hyd)–H2O(l) system, with special emphasis on the transformation of the amorphous hydrous/hydroxide solid phases into the thermodynamically stable crystalline oxides.

Manceau A., Steinmann S.N.

Li Z., Piankova D., Yang Y., Kumagai Y., Zschiesche H., Jonsson M., Tarakina N.V., Soroka I.L.

The role of intermediate phases in CeO2 mesocrystal formation from aqueous CeIII solutions subjected to γ-radiation was studied. Radiolytically formed hydroxyl radicals convert soluble CeIII into less soluble CeIV . Transmission electron microscopy (TEM) and X-ray diffraction studies of samples from different stages of the process allowed the identification of several stages in CeO2 mesocrystal evolution following the oxidation to CeIV : (1) formation of hydrated CeIV hydroxides, serving as intermediates in the liquid-to-solid phase transformation; (2) CeO2 primary particle growth inside the intermediate phase; (3) alignment of the primary particles into "pre-mesocrystals" and subsequently to mesocrystals, guided by confinement of the amorphous intermediate phase and accompanied by the formation of "mineral bridges". Further alignment of the obtained mesocrystals into supracrystals occurs upon slow drying, making it possible to form complex hierarchical architectures.

Wang C., Smieszek N., Chakrapani V.

Cervantes-Avilés P., Huang X., Keller A.A.

Knowledge of dissolution, aggregation, and stability of nanoagrochemicals in root exudates (RE) and soil leachate will contribute to improving delivery mechanisms, transport in plants, and bioavailability. We characterized aggregation, stability, and dissolution of four nanoparticles (NPs) in soybean RE and soil leachate: nano-CeO2, nano-Mn3O4, nano-Cu(OH)2, and nano-MoO3. Aggregation differed considerably in different media. In RE, nano-Cu(OH)2, and nano-MoO3 increased their aggregate size for 5 days; their mean sizes increased from 518 ± 43 nm to 938 ± 32 nm, and from 372 ± 14 nm to 690 ± 65 nm, respectively. Conversely, nano-CeO2 and nano-Mn3O4 disaggregated in RE with time, decreasing from 289 ± 5 nm to 129 ± 10 nm, and from 761 ± 58 nm to 143 ± 18 nm, respectively. Organic acids in RE and soil leachate can be adsorbed onto particle surfaces, influencing aggregation. Charge of the four NPs was negative in contact with RE and soil leachate, due to organic matter present in RE and soil leachate. Dissolution in RE after 6 days was 38%, 1.2%, 0.5%, and

Ghosalya M.K., Li X., Beck A., van Bokhoven J.A., Artiglia L.

Understanding the surface chemistry of ceria nanoparticles in a water environment is of fundamental interest for several research fields and notably in catalysis and biology/biochemistry. Particula...

Stanberry J., Szlamkowicz I., Purdy L.R., Anagnostopoulos V.

Birnessite oxidizes insoluble TcO2 to mobile TcO4− in the absence of oxygen through consecutive steps of sorption, electron transfer and subsequent dissolution in the aqueous phase.

Zhu J., Dressel W., Pacion K., Ren Z.J.

Environmental Science & Technology (ES&T) has served a leadership role in reporting advanced and significant research findings for decades and accumulated tremendous amount of high-quality literature. In this study, we developed tailored text mining methods and analyzed 29 188 papers published in ES&T from 2000 to 2019, and we performed data-driven analyses to reveal some critical information and guidance on what has been published, what topical changes have evolved, and what are the areas that deserve additional attention. While top research keywords remained stable (water, sorption, soil, emiss, oxid, exposur), the trending up and emerging keywords showed clear shift over the years. Keywords related to nanobased materials (nanoparticl, nanomateri, carbon nanotub), climate and energy (climat, ch4, greenhouse gas emiss, mitig, energi), and health (exposur, health, ingest) demonstrated the strongest uptrend in the past 10 years, while plastics and PFAS were among clear emerging topics in the past 5 years. Co-occurrence analysis showed distinct associations between media (water, soil, air, sediment), chemicals (pcb, humic subst, particulate matt), processes (sorption, remov, degrad), and properties (kinet, mechan, speciat). Furthermore, a rule-based classification deciphered trends, distributions, and interconnections of articles based on either monodomains (air, soil, solid waste, water, and wastewater) or multidomains. It found water and wastewater cross-discipline articles tended to have higher citation values, while air domain tended to stand alone. Water and air monodomains consistently increased their shares in publications (together 56.3% in 2019), while shares of soil studies gradually declined. This study provides new data-driven methods on literature mining and offers unique insights on environmental research landscape and opportunities.

Scheinost A.C., Claussner J., Exner J., Feig M., Findeisen S., Hennig C., Kvashnina K.O., Naudet D., Prieur D., Rossberg A., Schmidt M., Qiu C., Colomp P., Cohen C., Dettona E., et. al.

ROBL-II provides four different experimental stations to investigate actinide and other alpha- and beta-emitting radionuclides at the new EBS storage ring of ESRF within an energy range of 3 to 35 keV. The XAFS station consists of a highly automatized, high sample throughput installation in a glovebox, to measure EXAFS and conventional XANES of samples routinely at temperatures down to 10 K, and with a detection limit in the sub-p.p.m. range. The XES station with its five bent-crystal analyzer, Johann-type setup with Rowland circles of 1.0 and 0.5 m radii provides high-energy resolution fluorescence detection (HERFD) for XANES, XES, and RIXS measurements, covering both actinide L and M edges together with other elements accessible in the 3 to 20 keV energy range. The six-circle heavy duty goniometer of XRD-1 is equipped for both high-resolution powder diffraction as well as surface-sensitive CTR and RAXR techniques. Single crystal diffraction, powder diffraction with high temporal resolution, as well as X-ray tomography experiments can be performed at a Pilatus 2M detector stage (XRD-2). Elaborate radioprotection features enable a safe and easy exchange of samples between the four different stations to allow the combination of several methods for an unprecedented level of information on radioactive samples for both fundamental and applied actinide and environmental research.

Gerber E., Romanchuk A.Y., Pidchenko I., Amidani L., Rossberg A., Hennig C., Vaughan G.B., Trigub A., Egorova T., Bauters S., Plakhova T., Hunault M.O., Weiss S., Butorin S.M., Scheinost A.C., et. al.

We report a full characterization of PuO2 nanoparticles at the atomic level and probe their local and electronic structure by a variety of methods available at the synchrotron and theoretical approaches.

Prieur D., Bonani W., Popa K., Walter O., Kriegsman K.W., Engelhard M.H., Guo X., Eloirdi R., Gouder T., Beck A., Vitova T., Scheinost A.C., Kvashnina K., Martin P.

Intrinsic properties of a compound (e.g., electronic structure, crystallographic structure, optical and magnetic properties) define notably its chemical and physical behavior. In the case of nanomaterials, these fundamental properties depend on the occurrence of quantum mechanical size effects and on the considerable increase of the surface to bulk ratio. Here, we explore the size dependence of both crystal and electronic properties of CeO2 nanoparticles (NPs) with different sizes by state-of-the art spectroscopic techniques. X-ray diffraction, X-ray photoelectron spectroscopy, and high-energy resolution fluorescence-detection hard X-ray absorption near-edge structure (HERFD-XANES) spectroscopy demonstrate that the as-synthesized NPs crystallize in the fluorite structure and they are predominantly composed of CeIV ions. The strong dependence of the lattice parameter with the NPs size was attributed to the presence of adsorbed species at the NPs surface thanks to Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. In addition, the size dependence of the t2g states in the Ce LIII XANES spectra was experimentally observed by HERFD-XANES and confirmed by theoretical calculations.

Yang W., Su Z., Xu Z., Yang W., Peng Y., Li J.

The structure-performance relationship of α-, β-, γ- and δ-MnO2 catalysts were studied. The four samples exhibited different activities of toluene oxidation in terms of distinct tunnel sizes, surface-active oxygen and redox properties. δ-MnO2 catalyst with K+ in the mezzanines of its layers presented the highest toluene oxidation activity under a GHSV of 60,000 mL·g−1 h−1, as well as good water resistance. HAADF images and EELS results showed that oxygen vacancies preferred to form on δ-MnO2 lattice with layer stack dislocations via Mn4+ reduction rather than β-MnO2 with good crystallization. These inherent-distorted structures with heterocations K+ improved the emerge-annihilate cycling of oxygen vacancies. In-situ DRIFTS results showed that toluene adsorption was facilitated via rapid dehydrogenation of methyl due to abundant surface adsorbed oxygen on δ-MnO2. In addition, benzoate, maleic and manganese carbonate on δ-MnO2 were the key intermediate species during toluene oxidation at relatively low temperatures.

Plakhova T.V., Romanchuk A.Y., Butorin S.M., Konyukhova A.D., Egorov A.V., Shiryaev A.A., Baranchikov A.E., Dorovatovskii P.V., Huthwelker T., Gerber E., Bauters S., Sozarukova M.M., Scheinost A.C., Ivanov V.K., Kalmykov S.N., et. al.

Understanding the complex chemistry of functional nanomaterials is of fundamental importance. Controlled synthesis and characterization at the atomic level is essential to gain deeper insight into the unique chemical reactivity exhibited by many nanomaterials. Cerium oxide nanoparticles have many industrial and commercial applications, resulting from very strong catalytic, pro- and anti-oxidant activity. However, the identity of the active species and the chemical mechanisms imparted by nanoceria remain elusive, impeding the further development of new applications. Here, we explore the behavior of cerium oxide nanoparticles of different sizes at different temperatures and trace the electronic structure changes by state-of-the-art soft and hard X-ray experiments combined with computational methods. We confirm the absence of the Ce(iii) oxidation state at the surface of CeO2 nanoparticles, even for particles as small as 2 nm. Synchrotron X-ray absorption experiments at Ce L3 and M5 edges, combined with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and small angle X-ray scattering (SAXS) and theoretical calculations demonstrate that in addition to the nanoceria charge stability, the formation of hydroxyl groups at the surface profoundly affects the chemical performance of these nanomaterials.

Daelman N., Capdevila-Cortada M., López N.

The catalytic activity of metals supported on oxides depends on their charge and oxidation state. Yet, the determination of the degree of charge transfer at the interface remains elusive. Here, by combining density functional theory and first-principles molecular dynamics on Pt single atoms deposited on the CeO2 (100) surface, we show that the common representation of a static metal charge is oversimplified. Instead, we identify several well-defined charge states that are dynamically interconnected and thus coexist. The origin of this new class of strong metal–support interactions is the relative position of the Ce(4f) levels with respect to those of the noble metal, allowing electron injection to (or recovery from) the support. This process is phonon-assisted, as the Ce(4f) levels adjust by surface atom displacement, and appears for other metals (Ni) and supports (TiO2). Our dynamic model explains the unique reactivity found for activated single Pt atoms on ceria able to perform CO oxidation, meeting the Department of Energy 150 °C challenge for emissions. The catalytic activity of metals supported on oxides depends on charge and oxidation states, but charge transfer at the interface is not well understood. A model investigating the dynamic charges and oxidation states of Pt/CeO2 single-atom catalysts now clarifies the nature of the active site.