XPS Measurements Research Articles

Transition mechanism and thermokinetic analysis of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics for nuclear waste forms based on in-situ synthesis

In this study, the novelly designed Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics were utilized as nuclear waste form to simultaneously immobilize simulated fission products Sr and actinide nuclides. The phase transition mechanism, thermokinetics and densification behavior of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics based on in-situ synthesis were systemically analyzed by XRD, in-situ XPS, TG-DSC, SEM and density measurements. The results demonstrate that the formation of Ce0.5Sm0.5PO4 solid solution phase preceded that of Sr0.5Zr2(PO4)3 phase, of which there is a valence change of Ce from Ce4+ to Ce3+ before 1023 K. Additionally, as for the exothermic crystallization enthalpy, change of exothermic crystallization enthalpy and activation energy, the values of Sr0.5Zr2(PO4)3 and Ce0.5Sm0.5PO4 phases in composite ceramics are 286.17 – 515.61 mJ, 19.11 – 35.38 J/g, 702.45 kJ/mol and 145.21 – 232.44 mJ, 9.26 – 15.44 J/g, 450.04 kJ/mol, respectively. It is then indicated that the formation of Ce0.5Sm0.5PO4 phase is definitely more favorable than that of Sr0.5Zr2(PO4)3 phase. Simultaneously, the relative densities of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics are more than 95 % when the sintering temperature exceeds 1273 K.

Catalytic Performance of CuZnAl Hydrotalcite-Derived Materials in the Continuous-Flow Chemoselective Hydrogenation of 2-Methyl-2-pentanal toward Fine Chemicals and Pharmaceutical Intermediates.

Hydrotalcite-derived materials are eco-friendly, cheap, and efficient catalysts of different reactions. However, their application in liquid-phase hydrogenation could be more extensive. Hence, this work concerns the application of three hydrotalcite-derived materials with different CuZnAl molar ratios in the liquid-phase continuous-flow hydrogenation of 2-methyl-2-pentenal (MPEA) at a wide range of temperature (298-378 K) and pressure (1 × 106-6 × 106 Pa). The catalytic investigations were supported by catalysts characterization by ICP-OES, TPR, in situ XRD, XPS, NH3-TPD, CO2-TPD, and TEM measurements on different stages of their biography. It was shown that the catalytic activity of these samples is related to the Cu0/Cu+ ratio. Depending on the reaction conditions, selectivity control is possible. All catalysts were 100% selective to 2-methylpentanal (MPAA)-sedative drug precursor, with low conversion, at temperatures ≤ 338 K at every pressure. However, the selectivity of the second desired product, fragrance intermediate, 2-methyl-2-penten-1-ol (MPEO), increased significantly at higher temperatures and pressures. It reached the unique value of 54% with 60% substrate conversion at 378 K and 6 × 106 Pa for the catalyst with the highest Cu loading. It was revealed that the production of significant amounts of MPEO is related to the reaction conditions, the Cu+ predominance on the surface, the hydrogen spillover effect, and the acid-base properties of these systems.

Efficiency and mechanism of high surface area mesoporous nanocast NC-LaCoO3 for activating peroxymonosulfate to degrade atrazine in water

A highly active perovskite is needed to activate peroxymonosulfate (PMS) into reactive oxygen species (ROS) to degrade organic pollutants in wastewater. High surface area LaCoO3 was fabricated via nano-casting employing mesoporous silica KIT-6 (a 3D material, first fabricated in Korea Advanced Institute of Science and Technology number 6) as the hard template. The NC-LaCoO3 showed a higher surface area (81.33 m2·g−1), pore volume (0.21 cm3·g−1) and pore diameter (7.78 nm), abundant acidic/basic sites, rich oxygen vacancies (OVs), and easily accessible active sites, as well as higher catalytic efficiency to degrade atrazine than uncast/citric acid-assisted perovskite (CA-LaCoO3), CA-La2O3 and Co3O4. Under the specific experimental condition (PMS concentration: 4.30 mM; catalyst dosage: 0.60 g·L−1; pH: 8.20; atrazine concentration: 10 mg·L−1; and room temperature), in 6.0 min, approximately 19.02 %, 56 %, 29.38 %, and 39.21 % of atrazine were degraded by sole PMS, CA-LaCoO3/PMS, CA-La2O3/PMS and Co3O4/PMS respectively, while it was completely degraded in 4.0 min in NC-LaCoO3/PMS. Moreover, 0.06 mg/L leaching of cobalt was detected during oxidation in the NC-LaCoO3 /PMS process. The NC-LaCoO3 depicted stable catalytic efficiency after six recycling terms. Radical scavengers depicted that SO4•− and •OH were produced as the main reactive species at the initial phase of the catalytic reaction, and subsequently, O2•− and 1O2 were generated as the secondary oxidative species. A comparatively dominant inhibitory effect of methanol compared to TBA suggested that SO4•− was mainly involved in atrazine degradation. XPS, EPR, in-situ ATR-FTIR, EIS, LSV, and chronoamperometric measurements were employed to explore the catalytic reaction mechanism. High catalytic efficiency was ascribed to better textural properties, diffusion-friendly structure, rich oxygen vacancies, and radical species. This research suggests that perovskites with a range of A and B metals can be synthesized by nanocasting using high surface area templates for advanced oxidation processes, especially PMS activation, to remediate organic wastewater.

Visible light-driven removal of Rhodamine B using indium-doped zinc oxide prepared by sol–gel method

Industrial dye contamination in wastewater poses significant environmental challenges, necessitating the development of efficient photocatalysts for degradation. In this work, we investigate the In doping effect in the photocatalytic activity of zinc oxide (ZnO) nanoparticles for effective RhB degradation. Indium-doped ZnO nanoparticles were synthesized via sol–gel method and x-ray diffraction (XRD) analysis revealed a wurtzite hexagonal structure, with the crystallite size being varying from 65 nm to 53 nm with the introduction of In content. XPS measurements on the 3% In-doped ZnO sample revealed distinct core level spectra for In 3d, Zn 2p, and O 1s regions, confirming the presence of indium, zinc, and oxygen. Brunauer–Emmett–Teller (BET) analysis revealed increased surface area and pore size, with specific surface areas escalating from 0.9 m²/g for pure ZnO to 10.1 m²/g for 3% indium-doped ZnO. Photocatalytic experiments exhibited significant RhB degradation, with degradation efficiencies reaching 93% for 3% indium-doped ZnO under visible light irradiation due to the effect of the presence of In, which causing light absorption enhancement, narrow the band gap and improve charge carrier separation. These findings underscore the potential of indium-doped ZnO nanoparticles as efficient and sustainable photocatalysts for wastewater treatment, offering a promising avenue to address environmental challenges associated with industrial dye-contaminated effluents.Graphical

Chitosan nanocoatings N-acylated with decanoic anhydride: Hydrophobic, hygroscopic and structural properties

Thin (ca. 340 nm) chitosan coatings were deposited onto glass substrates via dip-coating, then modified with the methanol solution of decanoic anhydride (0.17–56 mM). NMR, FTIR and XPS measurements confirmed that the acylation degree increased from 18 % to 45 %, and at the highest degree, the whole layer was acylated homogeneously by the reagent molecules. The coating thickness increased (up to 60 %), and the refractive index decreased (from 1.541 to 1.532) due to the acylation, that was determined by UV–visible spectroscopy. The AFM did not reveal morphological changes, but wetting tests showed that the acylation rendered the coating hydrophobic (water contact angle increased from ca. 75° to 100°). The contact angle, however, decreased to 85° due to the development of a second molecular layer of the decanoic acid by-product at the highest (over 25 mM) reagent concentrations. XRD studies showed a self-assembling structuring of the alkyl-chains in the bulk phase, which occurred in the case of the highest degree of acylation. This also manifested itself in a significant decrease of the layer hygroscopicity: the swelling degree decreased from 40 % to 8 % in a saturated water atmosphere monitored by spectroscopic ellipsometry.

The effect of low salinity water on wettability alteration of oil-wet calcite surfaces

To shed light on the chemical and physical aspects of low-salinity (LS) water flooding to enhance oil recovery, we explored the impact of the brine salinity on the modifications of the oil-calcite interface using a multi-technique surface science approach based on FTIR, AFM, XPS, and Contact angle measurements. Our findings reveal that Nujol-model oil adsorbs on fresh-cleaved CaCO3 (104) surface and initially forms a continuous film. Chemical and morphological surface characterizations were performed on oil-wet calcite, followed by their conditioning with formation (FW), demineralized (DW), and low salinity water (LS25, LS50, LS75, and LS100). The oil removal was quantified by semi-quantitative FTIR analysis and was found to vary from ∼20 % for FW up to ∼81 % for LS75 conditioning. In the investigated experimental conditions the fresh-cleaved calcite surface is most efficiently converted from oil-wet to water-wet when conditioned with LS75 brines. Significant surface wettability alterations were observed for LS 75 brines as contact angle measurements were found to reach a minimum contact angle of ∼18°. The changes in calcite wettability correspond to the formation of fragmented oil islands and calcite step bunches, the signature of surface dissolution, and changes in the oil-calcite chemical interactions. A model for Nujol adsorption and its detachment from the calcite surface was proposed for oil removal, competitive mechanisms related to the brine chemical composition are discussed.

Chemoselective Adsorption of Allyl Ethers on Si(001): How the Interaction between Two Functional Groups Controls the Reactivity and Final Products of a Surface Reaction.

Selective adsorption of multifunctional molecules is rarely observed when the different functional groups react via nonactivated reaction channels. Although the latter is also the case for ether cleavage and the adsorption of C=C double bonds on the highly reactive Si(001) surface, we find that allyl ethers, which combine both functional groups, react on Si(001) selectively via the cleavage of the molecules' ether group. In addition, our XPS measurements at 90, 150, and 300 K indicate an increased reactivity of the ether group when compared to monofunctional ethers. STM investigations furthermore reveal different final adsorption configurations after ether cleavage of allyl methyl ether when compared to diethyl ether as the monofunctional reference molecule. The interaction of the two functional groups in one molecule thus leads to new reaction channels with higher reactivity for ether cleavage on Si(001). As a further consequence, the reactivity of the C=C double bond is suppressed up to room temperature, leading to the observed selective adsorption.

The dual luminescence of M2MgTeO6 (M= Sr, Ba) double perovskites

Sr2MgTeO6 (SMT) and Ba2MgTeO6 (BMT) ceramics with the double perovskite structure have been synthesized by solid-state route and by thermal decomposition of nitrate solution precursor. Both compounds possess interesting and unexpected emission properties in the visible and NIR regions, never reported before for this type of materials. These properties have been measured in different experimental conditions in order to characterize their nature. The literature information on tellurium containing luminescent materials is not rich and the data are somewhat contradictory: nevertheless, they agree in assigning the emission properties to Te4+ in octahedral coordination, whereas the Te6+ ion is considered not luminescent. The presence of Te4+ ions has then been verified by XPS measurements. On the basis of the experimental evidences, the visible luminescence has been assigned to a transition between the electronic levels of the Te4+ ion. The origin of the NIR emission appears more difficult to assess: among the explored hypotheses, the most convincing one, at the present level of the information, involves the possible interactions between the Te4+ and Te6+ ions with consequent formation of an optically active charge transfer state, as already observed for other ns2-type ions (Bi3+, Sb3+).

Thermoelectric properties of reduced TiO2 -SrF2 composites

Highly stable thermoelectric materials based on inexpensive elements have great potential for heat recovery in high temperature applications. TiO2-d and SrTiO3 based thermoelectric materials are of great interest due to this reason. In this study TiO2–SrF2 based compounds were produced, to study the effect of fluorine on the thermoelectric properties of TiO2 type materials. From XPS measurements it is clear that some exchange from the TiO2–SrF2 happens forming a TiOxFy type phase. The electronic properties of the compound are very similar to the electronic properties of reduced TiO2 while some improvement is seen in the reduction of the thermal conductivity. A higher activation energy in the SrF2 rich samples might allow for increased electronic conductivity at higher temperatures interesting for further studies.

Adsorption of fluoride ion on Al/La modified acidified attapulgite composite materials

This study developed a novel fluoride ion adsorbent material (Al/La-A) for efficient removal of fluoride ions in water. The crystal structure, elemental composition, surface morphology, specific surface area, thermal stability and surface electronegativity before and after modification were explored using FTIR, XRD, XPS, SEM-EDS, BET, TG-DSC, and zeta potential measurements. Results showed that the fluoride ion adsorption capacity of Al/La-A reached 130.42 mg/g, with the surface area increasing from 65.66 m2/g to 111.68 m2/g, respectively, compared to unmodified attapulgite. Al/La-A maintained excellent fluoride ion removal performance over a wide pH range, with the best adsorption at pH 2. Coexisting ion experiments indicated weak competitive adsorption effects of Cl-, SO42-, and HCO3–, with fluoride ion adsorption remaining above 100 mg/g in the presence of different concentrations of coexisting anions. After 5 adsorption–desorption cycles, Al/La-A exhibited strong adsorption capacity and reusability. The fitting of Langmuir adsorption model and pseudo-second-order kinetic model to the adsorption of fluoride ions on Al/La-A indicated that the adsorption of fluoride ions on Al/La-A was primarily monolayer chemical adsorption. The adsorption mechanism of fluoride ions involved electrostatic interactions, ion exchange, and coordination complexation. This study provides a new research approach for the optimal utilization of attapulgite-based adsorbent materials and the efficient removal of fluoride-containing wastewater.

Y3+ doping induced phase segregation and its influence on luminescence of SrLaGa3O7: Mn4+

Sr(La, Y)Ga3O7: Mn4+ phosphors were prepared by sintering at 1400 ℃. The structural characteristics of phosphors were analyzed by means of XRD measurements. Surface compositions and chemical state of the elements were gained from XPS measurements. And the vibration and rotation information of the molecular structure was detected in Raman spectra. The phosphors show characteristic excitation spectrum of Mn4+, which puts down to the electronic transition of 4A2g→4T1g and 4A2g→4T2g. Exciting at 380 nm, the phosphors emit deep red light resulting from the 2Eg→4A2g transition. The Y3+ substitution influences crystal structure and photoluminescence performance obviously. The incorporation of a small amount of Y3+ reduces the cell volume and induces impurity phase of Y3Ga5O12 in all prepared phosphors. The band peaking at 715 nm decreases highly and the band becomes stronger when x ≥ 0.4.

Salt promoted metallic Pt photodeposition on graphitic carbon nitride towards efficiently photocatalytic hydrogen evolution

The photocatalytic hydrogen evolution (PHE) activity of pristine graphitic carbon nitride (GCN) and highly crystalline K+-doped GCN can significantly be enhanced under visible light irradiation via adding alkali metal salt into their PHE reaction solution. As manifested in XRD, UVDRS, TEM and XPS measurements, the loading amount of Pt cocatalyst on both GCN and K+-doped GCN, as well as the content of metallic Pt were greatly increased in the presence of 1.0 M KCl solution in the photoreduction solution. More significantly, the proportion of metallic Pt reached around 75 %. As a result, the PHE rate of K+-doped GCN was even as high as 11 mmol h–1g−1 under visible light irradiation. The current work offers a simple and cost-efficient strategy to promote the low depositing efficiency of Pt cocatalyst by traditional photoreduction method, thereby increasing the PHE activity of GCN and GCN based materials.

The surface modification of the silica-coated magnetic nanoparticles and their application in molecular diagnostics of virus infection

The study presents a series of examples of magnetic nanoparticle systems designed for the diagnosis of viral diseases. In this interdisciplinary work, we describe one of the most comprehensive synthetic approaches for the preparation and functionalization of smart nanoparticle systems for rapid and effective RT-PCR diagnostics and isolation of viral RNA. Twelve different organic ligands and inorganic porous silica were used for surface functionalization of the Fe3O4 magnetic core to increase the number of active centres for efficient RNA binding from human swab samples. Different nanoparticle systems with common beads were characterized by HRTEM, SEM, FT-IR, XRD, XPS and magnetic measurements. We demonstrate the application of the fundamental models modified to fit the experimental zero-field cooling magnetization data. We discuss the influence of the nanoparticle shell parameters (morphology, thickness, ligands) on the overall magnetic performance of the systems. The prepared nanoparticles were tested for the isolation of viral RNA from tissue samples infected with hepatitis E virus—HEV and from biofluid samples of SARS-CoV-2 positive patients. The efficiency of RNA isolation was quantified by RT-qPCR method.

The role of Cu and film thickness on the photocatalytic activity of mesoporous spin coated TiO2 films

Most practical applications of photocatalysts will involve coatings on an inert support; here we have examined how copper doping of spin coated porous TiO2 films affects their physical characteristics and photocatalytic activity. The photocatalytic degradation of stearic acid was used as a measure of photocatalytic activity for catalysts spin coated from a sol-gel onto glass with 0, 0.1, 0.5, 1, 2.5 and 5 wt% copper introduced into the catalyst lattice before gelation. The effects of spin coating speed on film thickness, structure and band gap were studied and the nature of the copper incorporated into the films examined with XPS and XANES measurements. Increased spin coating speeds reduces the thickness of the deposited films from ∼ 50 μm to ∼ 20 μm until a spin speed of ∼ 3000 rpm at which point non-Newtonian behaviour of the gels prevents further reductions in film thickness. A larger effect on film thickness is the presence of the added copper nitrate which results in thinner films. After calcining, XANES shows the bulk of the copper to be in a Cu(II) state but at the surface of the thinnest, most active films XPS shows only Cu(I). Photocatalytic activity is much more strongly affected by the presence of the copper than the thickness of the films with 0.1 wt% Cu catalysts as much as 10 times more active than the undoped catalysts. Increasing the copper content, however, reduces activity until at ∼ 5 wt% activity is lower than for the pure TiO2 films.

Uncovering fabrication approach impact on photocatalytic ciprofloxacin (CIP) antibiotic degradation of brookite TiO2

Solar-driven antibiotic degradation by semiconductor photocatalysis technique offers a promising route to tackle with the environmental issue we are currently facing. Herein, three kinds of brookite TiO2, TiO2-Glycerol (GL)/NaOH (OH−), TiO2-Ethylene glycol (EG)/Ethylenediamine (EDA), and TiO2- Ethylene glycol (EG)/NaOH (OH−), are prepared by changing fabrication approaches from as-prepared two different Ti-polyol precursors. The composition and structure of the above brookite nanocrystals is studied in detail, and the effects of different synthesis methods on their optical properties, surface areas and wettability, and photocatalytic degradation activities are discussed. The photocatalytic ciprofloxacin (CIP) remediation evaluation shows that the TiO2-EG/EDA enriched amine group confirmed by FTIR and XPS measurements has the highest dark adsorption as well as subsequent photocatalytic degradation activities compare with the other two types of brookite. Subsequently, the unveiling on how the TiO2-EG/EDA effectively degrades the CIP molecules is achieved. Indeed, on the basis of a series of characterizations, the good CIP adsorption capacity resulted from the weakest hydrophilicity, the largest specific surface area, the unique chemisorption effect by surface amine group, combining with the smallest band gap, the fastest photogenerated charge transport speed, the longest photogenerated electron lifetime and the most active sites, contribute to the rapid degradation of CIP upon the TiO2-EG/EDA. In addition, the CIP degradation pathway is proposed by HRMS analysis, and the EPI suite program predicts the intermediate molecules have no biotoxicity for the environment. It is expected this work could provide useful reference for highly-efficient photocatalytic antibiotics-degradation in terms of experimental design and materials fabrication.

Feasibility of using 2304 duplex stainless steel in seawater-mixed concrete pore solutions: A preliminary passivation consideration

Due to the growing shortage of fresh water resources worldwide, it is necessary to explore the feasibility of using seawater to produce concrete. However, the passivation and pitting corrosion resistance of reinforcing steel will inevitably be impaired by the chlorides contained in seawater. Therefore, it is particularly important to develop a corrosion-resistant steel that could be employed in seawater-mixed concrete. One option being considered is using duplex stainless steel (DSS). To evaluate the feasibility of application in seawater-mixed concrete, the passive films of 2304 DSS were both generated by cyclic voltammetry and naturally formed in alkaline solutions with and without admixed chlorides, which was further compared with those of the conventional low-carbon steel (HRB400E steel). Unlike 2304 DSS, HRB400E steel failed to be passivated with admixed chlorides. Furthermore, the passive film of 2304 DSS was investigated by EIS, AFM and XPS measurements. Although the passivation ability was slightly reduced by admixed chlorides, and the morphology and composition of passive film were also modified, the high pitting corrosion resistance of 2304 DSS guaranteed its application in seawater-mixed concrete.

Fabrication and catalytic activities of ZnSnO3/C nanofibers in the piezo/photocatalysis of diclofenac

Piezo-photocatalysis is a “green” approach to decompose various pollutants using natural clean energy. Herein, a series of ZnSnO3/C nanofibers with excellent piezo-photocatalytic activities were reported. The XRD, TEM and SEM, as well as XPS measurements were carried out and the results indicate that ZnSnO3/C nanofibers with the orthorhombic phase were fabricated successfully. The UV–vis absorbance spectra, photocurrent response, EIS curves and photoluminescence characteristics indicate that the incorporated C decreases the band gap of ZnSnO3 and improves separation efficiency of photoinduced charge-hole pairs, which results in higher catalytic activity of ZnSnO3/C nanofibers. The photocatalytic, piezocatalytic and piezo-photocatalytic activities were investigated by degrading diclofenac. The ZnSnO3/C‒0.3 ‰ has the highest reaction constant among the series of catalysts. The reaction constat of ZnSnO3/C‒0.3 ‰ in photocatalysis process (0.0185 min−1) is 2.15 times that of ZnSnO3. The reaction constat of ZnSnO3/C‒0.3 ‰ in piezo-photocatalysis process (0.0549 min−1) is 2.97 times that of ZnSnO3/C‒0.3 ‰ in photocatalysis and 3.47 times that of ZnSnO3 in piezo-photocatalysis (0.0158 min−1). The •OH and e− radicals are key roles for degrading diclofenac in catalysis processes.

Phosphorus-modification of Pt/Al2O3 catalysts improves dispersion and cycloalkane dehydrogenation activity

In this study, we demonstrate that phosphorus-modification of Pt/Al2O3 leads to sinter-stable catalysts with improved activity in the dehydrogenation of perhydro benzyltoluene, an attractive liquid organic hydrogen carrier. TEM images show that platinum nanoparticles are stabilized to a size below 1 nm by the P-modification procedure, while unmodified counterparts show considerable sintering after reduction at 600 °C. The modification procedure starts by a simple impregnation of Pt/Al2O3 with H3PO3, followed by a high temperature treatment above 550 °C. It is crucial to adjust the right P:Pt ratio to reach stabilization of all platinum nanoparticles and thereby high catalytic surface areas. In our dehydrogenation studies, a catalyst with the optimal molar P:Pt ratio of 1.8 shows a 18 % higher activity compared to the unmodified sample. Even after treating the catalyst at temperatures up to 900 °C, this activity boost remains. XPS and XRD measurements prove that Pt stays in its reduced elemental state, also after P-modification, which is essential for a good dehydrogenation activity. The phosphorus species act as an anchor for the Pt particles on the Al2O3 surface, reducing their mobility and preserving small nanoparticles.

In-situ constructing an innovative and versatile nanotraps for incorporation of zero–valent iron nanoparticles into zeolite imidazole framework–8 towards high efficient detoxification and imprisonment of U(VI) and Se(IV) from water via a combination study of capture performance and underlying mechanism aspects

This work reported an in-situ constructing of innovative and versatile nanotraps (NZVI/ZIF–8) namely incorporation of zero–valent iron nanoparticles (NZVI) into zeolite imidazole framework–8 (ZIF–8), and the application of the as-constructed NZVI/ZIF–8 in high efficient detoxification and imprisonment of U(VI) and Se(IV) from wastewater. The results demonstrated that controllable incorporation of NZVI with ZIF–8 used advantages of each component to generate an emphatic boosted interaction in U(VI)/Se(IV) imprisoning. The kinetic adsorption for U(VI)/Se(IV) imprisoned onto NZVI/ZIF–8 was described by pseudo-second-order model well, and the adsorption isotherms followed the Langmuir model better. Thermodynamic analysis (ΔG < 0, ΔS > 0, ΔH > 0) demonstrated that U(VI)/Se(IV) imprisoned onto NZVI/ZIF–8 was endothermic and spontaneous. XPS measurements unveiled that NZVI/ZIF–8 imprisoned U(VI)/Se(IV) by synergistic mechanism of adsorption and reduction. The N–containing functional groups on ZIF–8 was primarily responsible for adsorption, while Fe(0) and surface enriched Fe(II) from NZVI predominantly contributed to reductive conversion of U(VI)/Se(IV) into U(IV)/Se(0). In a word, ZIF-8 played an important role in imprisonment of U(VI)/Se(IV) onto the as-constructed NZVI/ZIF–8 nanotraps with intensified reactivity in comparison with naked NZVI. The findings revealed that the NZVI/ZIF–8 nanotraps would be superb scavengers towards U(VI)/Se(IV), and implied a bright future in potential application in nuclear waste management.

Improved Compatibility of α-NaMnO2 Cathodes at the Interface with Ionic Liquid Electrolytes.

The behaviour and compatibility of monoclinic sodium manganite, α-NaMnO2, cathodes at the interface with electrolytes based on the 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI) and N-trimethyl-N-butylammonium bis(fluorosulfonyl)imide (N1114FSI) ionic liquids is presented and discussed. The Na+ insertion process was analysed through cyclic voltammetry tests combined with impedance spectroscopy measurements and the cell performance was tested by charge-discharge cycles. XPS and FIB-SEM measurements allowed analysis of the surface composition and the morphology of post-mortem cathodes. Overall, the α-NaMnO2 cathode showed high reversibility in N1114FSI-based electrolyte, delivering 60 % of the initial capacity after 1200 cycles in conjunction with a Coulombic efficiency above 99 %. To our knowledge, these very promising results are the best result obtained till now for monolithic α-NaMnO2 cathodes, are ascribable to the formation of a stable passive layer onto the electrode surface, as confirmed by spectroscopic analysis.