Cerium Ions Research Articles

Metallic surface doping of metal halide perovskites

Intentional doping is the core of semiconductor technologies to tune electrical and optical properties of semiconductors for electronic devices, however, it has shown to be a grand challenge for halide perovskites. Here, we show that some metal ions, such as silver, strontium, cerium ions, which exist in the precursors of halide perovskites as impurities, can n-dope the surface of perovskites from being intrinsic to metallic. The low solubility of these ions in halide perovskite crystals excludes the metal impurities to perovskite surfaces, leaving the interior of perovskite crystals intrinsic. Computation shows these metal ions introduce many electronic states close to the conduction band minimum of perovskites and induce n-doping, which is in striking contrast to passivating ions such as potassium and rubidium ion. The discovery of metallic surface doping of perovskites enables new device and material designs that combine the intrinsic interior and heavily doped surface of perovskites.

Enhanced Crystallinity and Luminescence Characteristics of Hexagonal Boron Nitride Doped with Cerium Ions According to Tempering Temperatures.

Hexagonal boron nitride was synthesized by pyrolysis using boric acid and melamine. At this time, to impart luminescence, rare earth cerium ions were added to synthesize hexagonal boron nitride nanophosphor particles exhibiting deep blue emission. To investigate the changes in crystallinity and luminescence according to the re-heating temperature, samples which had been subjected to pyrolysis at 900 °C were subjected to re-heating from 1100 °C to 1400 °C. Crystallinity and luminescence were enhanced according to changes in the reheating temperature. The synthesized cerium ion-doped hexagonal boron nitride nanoparticle phosphor was applied to the anti-counterfeiting field to prepare an ink that can only be identified under UV light.

Cyclic oxygen exchange capacity of Ce-doped V2O5 materials for syngas production via high-temperature thermochemical-looping reforming of methane.

Synthesis gas production via solar thermochemical reduction-oxidation reactions is a promising pathway towards sustainable carbon-neutral fuels. The redox capability of oxygen carriers with considerable thermal and chemical stability is highly desirable. In this study, we report Ce-doped V2O5 structures for high-temperature thermochemical-looping reforming of methane coupled to H2O and CO2 splitting reactions. Incorporation of fractional amounts of large cerium cations induces a V5+ to V3+ transition and partially forms a segregated CeVO4 phase. More importantly, the effective combination of efficient ion mobility of cerium and high oxygen exchange capacity of vanadia achieves synergic and cyclable redox performance during the thermochemical reactions, whereas the pure vanadia powders undergo melting and show non-cyclic redox behaviour. These materials achieve noteworthy syngas production rates of up to 500 mmol molV−1 min−1 during the long-term stability test of 100 CO2 splitting cycles. Interestingly, the cerium ions are mobile between the lattice and the surface of the Ce-doped vanadia powders during the repeated reduction and oxidation reactions and contribute towards the cyclic syngas production. However, this also causes the formation of the CeVO4 phase in Ce-rich powders, which increases the H2/CO ratios and lowers fuel selectivity, which can be controlled by optimizing the cerium concentration. These findings are noteworthy towards the experimental approach of evaluating the oxygen carriers with the help of advanced characterization techniques.

Ce ion surface-modified TiO2 aerogel powders: a comprehensive study of their excellent photocatalytic efficiency in organic pollutant removal

The surface modification of TiO2 aerogel powders by cerium ions has led to enhanced photoinduced properties.

Reduced Graphene Oxide-Resorcinol Nanocomposite: A Chemosensor for the Detection of Cerium Ions

A hybrid material reduced graphene oxide based organic nanocomposite was synthesized from graphite by modified Hummers method, which is further chemically reduced to form reduced graphene oxide (rGO) and with resorcinol through a solvothermal process a reduced graphene oxide-resorcinol (rGO-R) nanocomposite was obtained. The synthesized materials surface morphology and structural compositions were studied through X-ray diffraction (XRD) and scanning electron microscope (SEM) and their optical properties were studied through UV-visible spectroscopy and photoluminescence. The material was further used as a fluorescent chemosensor to detect cerium ion under aqueous conditions. The rGO-R composite’s sensing abilities were studied by following parameters viz. pH, reversibility, time and the interference of other probable competing ions. The sensing follows both the photo-induced electron transfer and intramolecular charge transfer processes.

Extraction of cerium(III) ions from dilute aqueous solutions by emulsion liquid membrane: effects of operating conditions, salts and natural water matrices

Extraction of cerium(III) ions from dilute aqueous solutions by emulsion liquid membrane: effects of operating conditions, salts and natural water matrices

Biosorption of neodymium(III) and cerium(III) ions by Loquat leaves (Eriobotrya japonica) kinetics and thermodynamic studies

Biosorption of neodymium(III) and cerium(III) ions by Loquat leaves (Eriobotrya japonica) kinetics and thermodynamic studies

Metal oxide based epoxy coatings for corrosion protection of steel

Abstract Decadence of metals is often due to several environmental factors. To prevent the deterioration of metals, a durable epoxy layer of metal oxides is utilized, that provide ultimate resistance and protection against corrosion. These metal oxides can be a monomer or a hybrid polymerized mixture of different components. This paper includes the study of epoxy film on steel to fight against corrosion using metal oxides of cerium ions, titanium dioxide, zinc oxide and graphene oxide and to describe the efficacy of these primers. Different techniques would be used with time monitored process such as Electrochemical studies, salt spray studies, FT-IR, XRD, TEM and XPS analyses that would reveal comparable results.

Investigation of dextran adsorption on polycrystalline cerium oxide surfaces

This study used non-reactive magnetron sputtered polycrystalline cerium oxide thin films as model substrates to mimic the surface morphology of cerium oxide nanoparticles. We investigated the interaction between dextran and polycrystalline cerium oxide surfaces by atomic force microscopy, X-ray photoelectron spectroscopy, and reflection-absorption infrared spectroscopy. A simplified sample preparation method probing solid-liquid interface was set up by conducting aqueous adsorption procedures in an argon-filled glove bag connected to an ultra-high vacuum chamber. We found that the adsorption of dextran from aqueous solution onto the polycrystalline cerium oxide surface leads to a mutual charge transfer between dextran and cerium ions, creating a surface accumulation of Ce3+. In the aqueous environment, dextran hydroxyl groups adsorbs on the polycrystalline cerium oxide surface competitively with the dissociated hydroxyl groups from water. By investigating glucose adsorbed onto polycrystalline ceria prepared by physical vapor deposition, we further confirmed the role of hydroxyl groups from polysaccharide during interaction with ceria. Thermal annealing of the dextran adsorbed polycrystalline cerium oxide surface results in desorption of weakly bonded dextran below 100 °C and decomposition of dextran above 100 °C.

The synergistic effect of cerium acetate and sodium sulphate on corrosion inhibition of AA2024-T3 at various temperatures

The present work examines the corrosion inhibition of aluminium alloy 2024-T3 immersed in NaCl+Ce(OAc)3 and NaCl+Ce(OAc)3+Na2SO4 solutions to evaluate the synergetic effect between cerium and sulphate ions at various temperatures (5 °C, 25 °C and 50 °C). The electrochemical properties were studied using short-term potentiodynamic measurements and long-term electrochemical impedance measurements. The surface topography, morphology and composition of cerium deposits formed on the alloy surface after two days of immersion were evaluated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results revealed an efficient long-term (up to 8 weeks) corrosion inhibition in NaCl+Ce(OAc)3 that was superior in the NaCl+Ce(OAc)3+Na2SO4 solution, especially at lower temperatures (5 °C > 25 °C > 50 °C). The composition of the Ce-based film varied with the temperature and the presence of Na2SO4, resulting in different mixtures of Ce(III) and Ce(IV) species. The synergistic effect of cerium and sulphate ions on corrosion inhibition was reflected by a higher degree of cerium oxidation from Ce3+ to Ce4+ at a low temperature and the incorporation of sulphates into the formed film, which protected the surface from the corrosion medium more efficiently.

Modification of SiOC-based layers with cerium ions - influence on the structure, microstructure and corrosion resistance

Amorphous silicon oxycarbide (SiOC) based materials are customarily called black glasses. In this work, hermetic layers on the steel substrate based on amorphous SiOC were obtained. The material was modified with cerium ions. Based on the literature, Ce as the modifier is responsible for i.e. enhancement of the corrosion resistance of materials and their antibacterial properties. SiCeOC coatings were produced via ceramization of the polymeric precursors synthesized by the sol-gel method and deposited on the metallic substrates with the use of the dip-coating technique. Numerous structural and microstructural studies were applied for the examination. It was proven that cerium is present in the material in the form of the inclusions and the material might be described as the SiOC/CeO2 composite. The surface properties such as roughness, wettability and surface free energy were also analyzed. Corrosion resistance tests were also conducted to establish the influence of the modification with cerium ions on the characteristics of the basal material. The results illustrated that a limited amount of the modifier enhanced corrosion resistance of black glasses without changes in their structure. However, the modification does not promote Ce ion release and the antibacterial tests showed the materials do not possess antibacterial properties.

Ce3+ triggers fenton-like processes in neutral solutions for effective catechol degradation

Classical Fenton and Fenton-like processes destruct organic pollutants in water non-selectively to complete mineralization. However, the usage of classical Fenton or Fenton-like processes is often limited due to the narrow operational pH window, sludge accumulation, inefficient H2O2 and efficiency decline. To overcome these constraints, in this study, we used a homogeneous Fe3+-Ce3+-H2O2 Fenton-like process to degrade catechol at different experimental conditions. At pH 7, almost 97% of 10 mM catechol can be destructed within 60 min while the degradation by Classical Fenton or Fe3+-H2O2 Fenton-like process only 36.2% and 23.7%. The resultant solution after the degradation contains only traces of cerium ions. The sludge created by the process was extensively characterized by FTIR and XPS spectroscopy to elucidate the fate of cerium ions. Electron spin resonance (ESR) data confirmed •OH as the major free radical in Fe3+-Ce3+-H2O2 process. Our Fenton-like process widens the optimal pH values to neutral condition.

Photo‐Electrochemical Device Enabling Luminescence Switching of LaPO4:Ce,Tb Nanoparticle Layers

AbstractThe luminescence properties of LaPO4:Ce,Tb nanoparticles are known to depend on the oxidation state of the cerium ions. However, their assembly into thin films exhibiting reasonable fast Ce3+/4+ electrochemistry is not trivial. Herein, the electrochemical luminescence switching of LaPO4:Ce,Tb nanoparticles, assembled as nonconducting thin films, using two electrocatalytic processes, is demonstrated. Due to the insulating nature of these nanoporous films, redox shuttles are used to access the redox active Ce3+/4+ species for electrochemical reactions. A series of redox shuttles with various redox potentials are employed to investigate their capability to electrochemically oxidize Ce3+ within the nanoparticles. Thereby the formal redox potential of the Ce3+/4+ couple in LaPO4:Ce,Tb nanoparticles is determined to lie within 0.89 and 1.15 V versus Ag/AgCl. In situ observation of repetitive luminescence switching is realized by assembling a device that allows UV light to enter the nanoparticle layer. With two redox shuttles present in the electrolyte, one for the oxidation of Ce3+ and the other for reduction of Ce4+, quenching and restoration of the luminescence is monitored. The resulting device represents the first down‐sizable logical AND gate with UV light and voltage inputs and a vis light output based on a solid state LaPO4:Ce,Tb layer.

AMPEROMETRIC DETERMINATION OF CERIUM (III) USING 2,7-DINITROZO-1,8- DIHYDROXYNAPHTHALENE-3,6-DISULFONIC ACID SOLUTION

Cerium and its compounds are widely used in the production of electronic devices and semiconductors, which is why these substances will enter the environment more often in the future. There is a need for effective express methods that can determine the trace amounts of cerium and other rare earth elements with high accuracy to control and study the possible negative impact of cerium compounds on the ecosystems. The objective of this research paper was to elaborate on an express method capable of producing accurate and reliable results on the content of cerium in wastewaters in the presence of other rare earth elements. The elaboration of the express method was carried out based on the amperometric titration method studying the effect of various buffer solutions on cerium determination. Moreover, the effect of strontium, lutetium, iron, yttrium, samarium, niobium, holmium, praseodymium, gadolinium, and erbium ions on acquisition accuracy of the cerium (III) ions in samples of process water was studied. The research results presented a method for the amperometric determination of cerium (III) applying 2,7-dinitroso-1,8-dihydroxynaphthalene-3,6-disulfonic acid on a rotating platinum disk microelectrode. The extraction-amperometric method of analysis was proposed for the analysis of process water. The optimal concentrations of background electrolytes and buffer mixtures and the voltage values, were determined; the stability constant of the complex was calculated; the lower limit of the determined cerium content was defined. No interfering influence of foreign ions on the determination of cerium (III) ions was observed. The developed method for determining cerium (III) has a simpler hardware design than the previously described method of pulsed direct current glow discharge mass spectrometry but has a higher detection limit.

A study on electrochemical hydrogen storage properties of truncated octahedron cobalt cerium molybdate nanocrystals synthesized by solution combustion method

Hydrogen energy is a key role in novel renewable energy production/consumption technologies. Traditional hydrogen energy systems are suffered from low density, high production cost, low efficiency, and storage complications. With the advent of solid-state hydrogen storage technology, many of above shortcomings are fulfilled, however, there are several unknown points, particularly in mixed metal oxides, which need more attention. Herein, we report the production of an engineered truncated octahedron shaped nanocrystal containing cobalt (Co), cerium (Ce), and Molybdenum (Mo) ions, emphasizing the general formula CoCe2(MoO4)4 via a solution combustion method. Experimental observations reveal that the CoCe2(MoO4)4 nanocrystals are purely formed in maltose at 700 °C, with almost regular truncated octahedron morphology, having an octahedral edge-size of around 45 nm. This morphological arrangement exhibits significantly an enhanced electrochemical hydrogen storage performance, in an alkaline medium, with maximum discharge capacity of ~4750 mAh/g.

Cerium ion(III)-triggered aggregation-induced emission of copper nanoclusters for trace-level p-nitrophenol detection in water

Herein, we provide the first report on the effects of Ce3+ addition on the fluorescence of copper nanoclusters (CuNCs), which have excellent optical properties and lower toxicity as compared to AgNCs and AuNCs. We synthesized glutathione-encapsulated copper nanoclusters (GSH-CuNCs) using a simple one-pot chemical reduction approach. The excitation/emission wavelengths of the GSH-CuNCs were 350/650 nm. Introduction of Ce3+ triggered an aggregation-induced emission of GSH-CuNCs due to formation of GSH-CuNCs-Ce3+ complexes, resulting in a prominent fluorescence enhancement (~42-fold) of the mixed system. Fluorescent intensities (FIs) for the GSH-CuNCs-Ce3+ system were significantly quenched by introduction of p-nitrophenol (p-NP). The aforementioned quenching mechanism resulted from an inner-filter effect producing nearly unchanged fluorescence lifetime and overlap between UV–Vis absorption of Ce3+ and the excitation wavelength of GSH-CuNCs. Consequently, a GSH-CuNCs-Ce3+-based “ON-OFF” platform was constructed for fluorescent detection of p-NP in water matrices. Under optimized conditions (5-min incubation time, pH = 5.6, 20 mM Ce3+), the FIs of the GSH-CuNCs-Ce3+ system were linear for p-NP concentrations from 0.5 to 500 μM and achieved a low detection limit of 0.17 μM. Moreover, the as-constructed nanofluoroprobe demonstrated high stability and specificity to p-NP, thereby offering a simple, cheap and robust experimental method for conventional monitoring of p-NP at trace levels in real-world water samples.

Structural and luminescence study of Ce3+ and Eu3+ doped ZnAl12O19 nano-structured novel phosphors

Cerium and Europium ions activated ZnAl12O19 nano-phosphors were first time prepared by solution combustion synthesis. The prepared powder samples were characterized by X-Ray Diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM), Ultraviolet visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR) and Photoluminescence technique (PL). The crystal structure of the prepared ZnAl12O19 host, and Ce3+ and Eu3+ doped ZnAl12O19 phosphors were calculated by XRD technique. The nano-structured nature of the prepared samples was confirmed by the HR-TEM technique. The band gap energies of prepared undoped, and Ce3+ / Eu3+ doped ZnAl12O19 nano-phosphor were calculated using the UV spectroscopy technique. The bonding nature in the prepared samples was studied by the FT-IR technique. Under 320 nm excitation wavelength, the PL emission spectrum of Ce3+ activated ZnAl12O19 nano-phosphor shows broad emission centered at 420 nm, which is ascribed due to the transitions of the 5d excited state to its ground-state configurations of the 2F7/2 of the Ce3+ ions. Furthermore, under 390 nm excitation the PL emission spectra of Eu3+ activated ZnAl12O19 nano-phosphor shows sharp emission peak at 590 nm corresponding to the 5D0→7F1 transition of Eu3+ ions. The CIE chromaticity coordinates for the optimum nano-phosphor were found to be (0.1573, 0.0693) and (0.5717, 0.4276) for Ce3+ / Eu3+ doped ZnAl12O19 phosphors, respectively. Therefore these synthesized phosphors may be applicable in display devices and solid state lighting applications.

Photocatalytic Studies of La,Ce Co-Doped ZnO Nanoparticles

Zinc oxide nanoparticles were co-doped with varying concentrations of lanthanum (La) and cerium (Ce) ions using co-precipitation method. The resulting powders were calcined in a muffle furnace for 1 h at a temperature of 500°C to produce La,Ce-doped ZnO nanoparticles of varying stoichiometry viz. (Zn0.98La0.01Ce0.01O, Zn0.96La0.02Ce0.02O, Zn0.94La0.03Ce0.03O, and Zn0.92La0.04Ce0.04O). This method of co-doping is cost effective and does not require any complex procedure, equipment or inert gases. The synthesized samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to study the size, phases and grain morphology. XRD patterns revealed the hexagonal wurtzite phase of the synthesized samples. The average size of the undoped and La,Ce co-doped ZnO nanoparticles, as calculated from XRD pattern, was found to be 25 nm. Further, the size of co-doped nanoparticles decreased significantly with increasing dopant concentration. Optical properties were studied through UV-Visible spectrophotometry. The photocatalytic activities of undoped and La,Ce co-doped ZnO nanoparticles were examined by observing the decomposition of Rhodamine B dye under UV lamp within 0–80 min. The Rhodamine B (RB) dye solution was efficiently photo-degraded within 35 min when using Zn0.92La0.04Ce0.04O as catalyst, mechanism of which has been thoroughly discussed below. Further, photoluminescence (PL) studies revealed the narrowing of band gap with increase in concentration of dopant ions as indicated by the red shift in the PL emission spectrum of co-doped nanoparticles.

Oxygen defect-induced NO− intermediates promoting NO deep oxidation over Ce doped SnO2 under visible light

A Ce doped SnO2 (Ce-SnO2) photocatalyst was constructed under the argon atmosphere with abundant oxygen vacancies (OVs) for adsorption and activation of NO and O2, aiming to promote NO deep oxidation removal efficiency under different relative humidity. It was found that the incorporation of cerium ions into SnO2 could results in the generation of OVs under argon atmospheres, which further promoted NO deep oxidation under visible light irradiation. The theoretical calculations results and in-situ DRIFTS demonstrated that NO was actively adsorbed at OVs sites to form the NO− intermediate and finally transformed to the harmless nitrate and nitrite products by the activated reactive oxygen species (ROS) at OVs sites. This process could occur continuously since more OVs were formed under visible light irradiation. This study maybe provides a new approach to design and synthesize high-efficient photocatalysts for NO removal.

Self-Assembly Fabrication of Honeycomb-like Magnetic-Fluorescent Fe3O4-QDs Nanocomposites for Bimodal Imaging.

Magnetic-fluorescent nanocomposites have a tremendous potential in biomedicine realms as a revolutionary dual-modality probe tool for more accurate medical detection. However, complicated and inefficient postprocesses pose obstacles to obtaining high-quality magnetic-fluorescent nanocomposites. Thus, the fabrication of magnetic-fluorescent functional nanocomposites via a simple, effective, and ideal method remains a challenge and is still waiting to be tapped. The new synthesis approaches are becoming impending demands and probably enable us to address these above-mentioned problems. In this contribution, we present a novel self-assembly synthesis route for the construction of magnetic-fluorescent bimodal imaging nanocomposites rather than adopting sophisticated postpreparative processes. The Fe3O4 and quatum dots (QDs) nanocomposites were cross-linked fleetly by cerium(III) ion driven coordination bonds in which the cerium(III) ions served as the cross-connecting node and the carboxylate groups acted as bridging ligands. The potential application for dual-modality imaging capability was validated on tumor-bearing mice. This ingenious strategy was extremely efficient and handy for the magnetic-fluorescent Fe3O4-QDs nanocomposite construction. Significantly, our cerium(III) ion driven self-assembly method probably has a wide applicability for nanoparticles and organic molecules containing carboxyl groups but extensive explorations are still necessary.