Reduction Of Ce Research Articles

Efficient recovery of rare earth elements from ion-adsorption rare earth tailings: Based on the addition of pyrite calcination modification

Rare earth tailings constitute a significant amount of solid waste that remains after industrial (NH4)2SO4 leaching and typically contain rare earth elements (REEs), primarily Ce. This study aimed to fully recover REEs from rare earth tailings by calcination with pyrite under both air and N2 atmospheres, followed by dilute H2SO4 leaching or bioleaching. The results of XRD, SEM-EDS, TIMA, SEM-BSE, XPS, and ICP-MS analyses indicated that Ce and Mn were mainly present in the form of CeO2 and MnO2, respectively, whereas Fe existed in both Fe2O3 and Fe2(SO4)3 forms. Leaching experiments with dilute H2SO4 demonstrated that the co-calcination of rare earth tailings with pyrite significantly enhanced the recovery of REEs. Notably, calcination in air resulted in a significantly higher extraction rate of Ce (95.55 %) than that in N2 (83.82 %). This difference was attributed to the presence of O2, which promoted the oxidation of pyrite and facilitated the reduction of Ce(IV) to Ce(III). In contrast, incomplete oxidation of pyrite occurred in the N2 atmosphere, leading to a high residual Ce(IV) content in the tailings that could not be leached by the dilute acid. Subsequently, sufficient recovery of Ce (97.52 %) from the tailings calcined in the N2 atmosphere was achieved by bioleaching using Acidithiobacillus ferrooxidans and pyrite. Thus, this study provides theoretical support for the efficient recovery of REEs from mining tailings or secondary sources containing CeO2.

Influence of cerium addition and redox state on silicate structure and viscosity

AbstractThe viscosities of Ce‐free and Ce‐bearing (∼1.3 mol%, ∼6.5 wt.% Ce2O3) soda lime silicate (window glass) melts were measured with respect to oxidation state. Experiments were performed isothermally using a concentric‐cylinder viscometer on melts equilibrated with successively reducing CO–CO2 gas mixtures within a gas tight vertical tube furnace at 1 atm. Viscosity measurement and sampling were performed at the end of each melt reduction step. Further, viscosities in the glass transition temperature range were estimated using the shift factor method applied to glass transition temperature values determined using differential scanning calorimetry (DSC) measurements on quenched glasses. The Ce speciation at each stepwise melt reduction was probed using Ce L3‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy, while structural information upon Ce addition and reduction was provided by Raman spectroscopy. The viscosities of these materials remain constant at this level of Ce addition and do not vary significantly with redox state at high temperature. Conversely, viscosity values in the glass transition temperature range increase upon both Ce addition and reduction. Our analysis, based on the glass composition analyses obtained via electron probe microanalyzer (EPMA), viscosity calculations, and observations of silicate structural changes, leads to the conclusion that the observed viscosity increase around the glass transition temperature is explained by the high ionic field strength of Ce ions as well as the polymerization behavior of the silicate matrix occurring during reduction of Ce. Because of its low concentration, resulting from its low solubility, Ce redox changes exert only minimal effects on the viscosity of this melt.

An LCA-BIM integrated model for carbon-emission calculation of prefabricated buildings

Carbon emissions from the building sector account for around half of China's national CEs and have been the obstacle to reaching China's two-carbon goal. However, whether the prefabricated technique can mitigate CEs for the building sector is still argued by studies. In consideration of this, this study proposes an LCA and BIM-simulation integrated model to comprehensively calculate CEs of prefabricated (PBs) and traditional cast-in-situ buildings (TBs). The BIM simulation is verified by an analytical method. The results show that the total carbon emission intensity (CEI) of PB is 9.61 % lower than that of the TB, showing a significant advantage in CE reduction potential and can be chosen as the developing direction in the future. The main CEs come from the operation and maintenance stage, where the TB emits 11.02 % higher CEs than those of the PB. For the materialization stage, where CEs are centralized in a short period, the difference between CEIs of the PB and TB is 3.32 %, which is not significantly different. The collected data and calculated results in this study can be quite beneficial to future sustainability studies in the same research domain, especially the integrated application of BIM and LCA. This study also contributes to knowledge by proposing a comprehensive CE calculation model and providing reasonable measures for CE reduction, which is beneficial to the sustainable development of the building sector to achieve China's two-carbon goal.

Ternary electrochemiluminescence biosensor based on Ce2Sn2O7@MSN luminophore and Au@NiO-CeO2 as a co-reaction accelerator for the detection of prostate specific antigen

A ternary ECL system was constructed with Ce2Sn2O7@MSN composite as luminophore, potassium persulfate as co-reactant and Au@NiO-CeO2 as co-reaction accelerator to realize ultra-sensitive biosensing detection of prostate specific antigen (PSA). The abundant oxygen vacancies in Ce2Sn2O7 endow it with powerful electrochemical redox ability, accelerate energy transfer, and ensure Ce2Sn2O7 excellent electrochemical luminescence performance as a luminophore. Furthermore, to optimize the luminescence energy, enhance stability, and reduce the background signal to improve its signal-to-noise ratio, a highly selective Ce2Sn2O7@MSN biological probe was obtained by coating cerium stannate (Ce2Sn2O7) with mesoporous silica nanospheres (MSN). Au@NiO-CeO2 with a large specific surface area and high oxygen vacancy activity was synthesized as the co-reaction accelerator, which promoted the generation of SO4•− through the rapid reversible oxidation and reduction of Ce4+/Ce3+, thereby the ECL signal amplified effectively. Under optimal conditions, the linear detection range of PSA spans from 100fg mL−1 to 100 ng mL−1, with a remarkable lowest detection limit of 0.037pg mL−1, showcasing significant application potential. This study provides a valuable reference for pyrochlore to be used as luminophore in the detection of various biomarkers by ECL biosensing.

Elucidation of synergism in Ce-Zr/SBA-15 mesoporous catalysts and the effects on the activity in selective glycerol to lactic acid reaction

The continued conversion of glycerol to value-added chemicals is essential in ensuring the sustainable development of the biodiesel industry. Selective catalytic oxidation of glycerol to lactic acid provides an alternative approach to valorizing glycerol. A mesoporous SBA-15 supported mixed-metallic oxide catalyst is deemed essential to selectively produce lactic acid in this mixed parallel and multi-step reaction. SBA-15-supported bimetallic Ce and Zr oxides were proved to be highly efficient catalysts for the selective glycerol oxidation into lactic acid in base-free media. The synergism between Ce and Zr in the bimetallic oxide compounds could enhance the creation of oxygen vacancies in the catalyst via the reduction of Ce4+ to Ce3+. The 2:1CeZr/SBA-15 catalyst exhibited prominent catalytic activity in selectively oxidizing glycerol to lactic acid, with a glycerol conversion of 91.8% and a lactic acid yield of 35.1%. This work achieved superior catalytic performance compared to previously conducted studies, primarily due to the significantly higher initial glycerol concentration employed in this study. To ascertain the intrinsic active sites of the catalyst, the physicochemical properties of the catalyst were thoroughly examined using BET, FTIR, XRD, FESEM, TEM, CO2-TPD, O2-TPD, and H2-TPR analysis. This work concluded that the synergistic interaction of the active sites, which led to the formation of active oxygen species, facilitated primary dehydrogenation of the terminal -OH bond in glycerol. Hence, in this work, a plausible glycerol conversion mechanism over the 2:1CeZr/SBA-15 catalyst was also proposed.

Influence of Di-n-butyl Phosphoric Acid on Cerium Redox and Speciation in Tri-n-butyl Phosphate.

The effects of simulated radiolytic degradation of tri-n-butyl phosphate (TBP) on the chemical speciation of cerium were studied by spectrophotometry and electrochemistry of TBP solutions containing increasing amounts of di-n-butyl phosphoric acid (HDBP), a common degradation product of TBP. Tetravalent cerium was found to exchange coordinated nitrate for the dibutyl phosphate anion, forming dinuclear complexes of the formula (CeOCe)(NO3)(6-d)(DBP)d·3TBP (d = 0-3). Compared to Ce(IV), Ce(III) was complexed less strongly by HDBP in TBP, but HDBP displaced both nitrate and TBP to form the series of mononuclear complexes Ce(NO3)(3-d)(HDBP·DBP)d·(3-d)TBP (d = 0-3). Dibutyl phosphate coordination caused large negative shifts in the Ce(IV/III) reduction potential in TBP, indicating a strong stabilization of the tetravalent state. Electrochemical investigation of the reduction of Ce(IV) in TBP revealed it to be a two-electron process in accordance with the dinuclear nature of the organic-phase Ce(IV) complexes. The diffusion coefficients of the d = 0 dinuclear Ce(IV)-nitrate-TBP complex and mononuclear Ce(III)-nitrate-TBP complex in TBP equilibrated with 7 M HNO3 were determined to be (1.16 ± 0.06) × 10-7 cm2/s and (1.9 ± 0.4) × 10-7 cm2/s, respectively, which also is consistent with the larger molecular volume of the dinuclear Ce(IV) complexes.

Can Mongolia feed the population with carbon mitigation to fortify nationally determined contribution?

Over 195 countries developed Nationally Determined Contributions (NDC) under the Paris Agreement to mitigate CEs (CE). Mongolia commits to a 22.7% reduction in CE by 2030 under the NDC goal. The study assessed the CE impact of local food production on the NDC of ceasing food imports under the Food Revolution Program (FRP). Findings indicated that Mongolia could not sustainably feed the population solely with domestic foods while achieving carbon mitigation goals concurrently. Relying on domestic production, it was projected that there would be a 7% increase in CE within agricultural food production, which constitutes 15% of the total emissions of the agriculture sector. The NDC targets an 18% (5238 Gg CO2eq) reduction in the agriculture sector by 2030; the study concluded that the mitigation goal would drop to 16.5% if foods are produced domestically under the FRP. This underscores the necessity of a strategic combination of local production (such as carrots, hen eggs, and rapeseed) and imports (like cabbage, cucumber, tomatoes, and chicken from the People's Republic of China) could effectively mitigate the CE. From a national perspective, combining import and local production proves beneficial; however, on the global scale, prioritizing local food production would be valuable to reduce the CE in food transportation and imported food production.

Trace Ce(III) boosted acidic peroxone (O3/H2O2) process for efficient water treatment: Essential role of oxalic acid complexation

The peroxone (O3/H2O2) process has long suffered from inefficient performance for water decontamination at acidic pHs. Herein, we find the evident capability of trace Ce(III) to boost the acidic peroxone process. In contrast to the negligible degradation (∼6% in 60 min) of oxalic acid (OA) as a recalcitrant compound in the O3/H2O2 system, efficient removal of OA (∼95 %) was achieved by introducing trace Ce(III) (0.30 µM). OA was identified as an effective ligand activating Ce(III) by forming the Ce(III)-OA complex, which served as the catalytic active component to accelerate the decomposition of O3 and H2O2 to produce •OH and promote the co-degradation of refractory pollutant atrazine and ibuprofen. The remarkable catalytic activity of trace Ce(III) for peroxone reaction resulted from the efficient interconversion of Ce(III/IV) relying on both the favorable electron transfer from the ternary Ce(III)-OA-hydroperoxo complex to O3 and the rapid reduction of Ce(IV) back to Ce(III) mainly by H2O2. Furthermore, the catalytic performance of Ce(III) for peroxone process outperformed Fe(II), Cu(II), and Co(II). This study puts forward an effective method to extrapolate the applicability of the peroxone (O3/H2O2) process to the acidic range and enlightens the development of Ce-catalyzed peroxone processes.

Green Public Finance and “Dual Control” of Carbon Emissions: New Evidence from China

In response to the escalating global climate change, countries are progressively adopting green public finance as a crucial instrument for achieving carbon neutrality. This study considers energy conservation and emission reduction (ECER) in demonstration cities’ construction as a natural experiment and verifies the effect of green public finance on total carbon emissions (TCEs) and carbon emission intensity (CEI) by using a difference-in-differences (DID) model with the help of the panel data of 276 Chinese cities from 2006 to 2019. The empirical results indicate that (1) the ECER policy effectively reduces CEs in the demonstration cities, resulting in a reduction of TCEs by 13.13% and CEI by 12.90%; (2) the ECER policy can help optimize energy structure, accelerate green technology innovation, and improve energy efficiency, thus promoting “dual control” of CEs; and (3) the CE reduction effect of the ECER policy is stronger in western cities, southern cities, lower-administrative-level cities, and cities with weaker financial strength, which has a typical “supporting the weak” effect. Based on this, we conclude that green public finance is conducive to promoting “dual control” of CEs. Our conclusions not only enrich the theoretical research on green public finance but also provide governments with empirical evidence to implement more effective green public finance policies and expedite carbon neutrality.

Correlation of electronic structure and magnetic properties of [formula omitted] nanostructure using synchrotron soft XAS

The present study reports crystalline structure, electronic structure and magnetic properties for nanoparticles undoped CeO2 and Ce1-xSmxO2 (x = 0.02 to 0.10, @ 0.02). The nanoparticle samples are synthesized by the co-precipitation method. XRD data shows the successful incorporation of Sm3+ ions at Ce4+ sites in the face-centered cubic (fcc) lattice. The soft X-ray absorption spectroscopy technique is utilized to get an insightful overview of electronic structural properties due to structural defects, chemical states and the development of oxygen vacancies in Ce1-xSmxO2 nanoparticles. The soft XAS spectra show a significant Ce and Sm peak in the M4,5 domain, along with the well-defined O K-edge peak. Analysis of Ce M4,5-edges indicates that Ce-ions have both 3 + and 4 + oxidation states. With the incorporation of Sm+3 ions, there is a reduction of Ce4+ states and oxidation of Ce3+ states, as well as a substantial increase in oxygen vacancy concentration. The room-temperature magnetic properties of Ce1-xSmxO2 nanoparticles reveal ferromagnetic behavior. The origin of ferromagnetism is explained by F-center exchange (FCE) coupling mechanisms mediated via development of oxygen vacancy and defects.

The reduction of copper in LaFeO3, La2CuO4 and CuO three-phase system improves the efficiency of NO removal: Experimental and density functional theory calculation

Hollow spherical LaCu0.5Fe0.5O3 (LCF) and La0.8Ce0.1Cu0.5Fe0.5O3 (LCCF) catalysts are synthesized by solvothermal method, and CuO is reduced in two samples, so that the two corresponding multiphase catalysts (R-LCF and R-LCCF) were prepared and used for the selective catalytic reduction of NO with CO (CO-SCR). The results show that the balance of Ce3++Cu2+↔Cu++Ce4+ between Ce and Cu ions promotes the reduction of CuO in the Ce-doped LCCF catalyst more obviously. In addition, the reduction of Ce and Cu in R-LCCF generates more oxygen vacancies, which leads to more surface adsorbed oxygen species, thus facilitating the conversion of more NO to NOx species. Besides, the presence of reduced Cu is highly active and can inhibit the production of carbonates occupying the active site. The ability to activate both CO and NO after the evolution of Cu0 to the key species Cu+ leads to a rapid reaction between Cu+-CO and NOx species. These are the key factors for the significant increase in catalytic activity at low temperatures. It is worth noting that the CO-SCR reaction on the R-LCCF catalyst corresponds to the Langmuir-Hinshlwood (L-H) and Eley-Rideal (E-R) mechanisms at different temperature windows, respectively.

Rapid and efficient extraction of cerium by forming Al-Ce alloys in LiCl-KCl molten salts

The extraction of lanthanides in spent fuel reprocessing plays a key role in the development of nuclear energy. In this work, the extraction of the typical fissionable cerium elements has been studied by electrolytic co-reduction of Al(III) and Ce(III) in LiCl-KCl-CeCl3 molten salts assisted by KAlCl4. The electrochemical behavior of the reduction of Al(III) and Ce(III) on a molybdenum electrode was studied by cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit chronopotentiometry (OCP), and specific peaks of five Al-Ce intermetallic compounds were detected. After 2.7 h of galvanostatic electrolysis at a current density of 0.064 A cm-2, the extraction efficiency and current efficiency of Ce(III) reached 99.9 % and 91.3 % respectively. Potentiostatic electrolysis is slightly more efficient, with 99.9 % Ce(III) extraction in 3.5 h at a current efficiency of 97.8 %. The products of electrolysis are rod-shaped alloys (Al11Ce3, Al3Ce, Al2Ce), and the molten salts purified by electrolytic separation are free of impurity signals and can be reused for electrolytic refining.

Electrochemical (co)reduction of Ce(III) and Fe(II) ions in a dicyanamide ionic liquid

Electrochemical (co)reduction of Ce(III) and Fe(II) ions in a dicyanamide ionic liquid

Switchable phase transitions from non-magnetic to magnetic cerium oxide nanoparticles using acoustic shock waves

In the present framework, we report a reversible magnetic phase transition that occurs from a mixed diamagnetic (nonmagnetic) state to a weak ferromagnetic (magnetic) state exhibited by cerium oxide nanoparticles (CeO2 NPs) under shocked conditions wherein the magnetic phase transitions are observed to be switchable phase transitions of mixed diamagnetic - weak ferromagnetic - mixed diamagnetic - weak ferromagnetic for the respective shock pulses of 0, 50, 100 and 150, which is probably reported for the first time, and the observed values of the saturation magnetization are 0.9117, 0.1022, 0.8783 and 3.7780 emu/g, respectively. The possible reasons behind the observed reversible magnetic phase transition are proposed by the outcomes attained from the spectroscopic and microscopic techniques. Based on the obtained analytical results, it is confirmed that the observed room temperature weak ferromagnetism is because of the enhancement of Ce3+ ions (reduction of Ce4+ ions) and oxygen vacancies such that the title material is suggested for the applications of magnetic sensors.

EXTH-33. RAGE INHIBITOR (TTP488) AS AN ALTERNATIVE TO DEXAMETHASONE FOR MANAGING CEREBRAL EDEMA FOLLOWING BRAIN TUMOR SURGERY

Abstract BACKGROUND Cerebral edema (CE) commonly occurs after neurosurgical procedures and contributes to patient morbidity and neurological deterioration. Corticosteroids alleviate brain edema during the perioperative period, but they impose several undesirable side effects and interfere with immunotherapies in patients with malignant brain tumors. OBJECTIVE To assess the anti-inflammatory effects of TTP488 (inhibitor of receptor for advanced glycation end products) on CE formation following tumor resection in glioma models. METHODS Mice harboring orthotopic CT-2A gliomas were randomly assigned to three groups and underwent tumor resection. TTP488, dexamethasone, and vehicle were administered perioperatively (day -4 pre-op to day 7 post-op) and post-operative neurological function was examined. CE was assessed on serial brain MRIs over a 7-day period, and using manual segmentation techniques, tumor-related volumes were calculated. In a separate survival experiment, the effect of each drug on anti-PD-1 immunotherapy response was measured. RESULTS In each group, CE peaked on post-operative day 2 and gradually diminished by day 7. On post-operative day one, mice treated with TTP488 showed a marked reduction in CE compared to those treated with either dexamethasone or vehicle with mean CE volumes of 1.75±1.08%, 2.69±0.77%, and 3.87±1.07%, respectively (P=0.02, TTP488 vs vehicle). Furthermore, the TTP488 group had better functional recovery scores (P=0.04) and wound healing (dehiscence, P=0.00003) compared to the vehicle group. Interestingly, unlike dexamethasone, TTP488 did not abrogate the efficacy of immunotherapy in the CT-2A glioma model. CONCLUSION TTP488 was as effective as dexamethasone in alleviating CE caused by tumor resection and did not interfere with the efficacy of immunotherapy. TTP488 could potentially be an alternative to dexamethasone in the perioperative management of patients undergoing tumor resection or other neurosurgical interventions.

Evaluation and calculation of urban carbon emission reduction potential based on spatiotemporal geographic model

With the growth of urban carbon emissions, found that the current urban carbon emission reduction potential assessment and calculation in carbon emissions data source, research index selection and cost are some problems, to promote the realization of low carbon emission reduction target, it is necessary to use space and space and geographical weighted regression model to obtain the spatial and temporal distribution of urban carbon reduction. This article combined geographic information system (GIS) technology to construct a spatial database. Based on the geographic weighted regression (GWR) model, a time dimension was introduced to construct a spatiotemporal GWR model, which was used to obtain the spatiotemporal distribution information of urban CEs and draw a spatial distribution (SD) map of urban CE reduction potential (RP). This article also conducted experimental tests on the carbon reduction potential (CRP) of Chinese cities by combining different carbon reduction (CR) measures. This paper uses three CR methods to test P of these cities respectively measure A adjust industrial structure, measure B to promote low carbon technology innovation and measure C is to optimize the urban space structure, the experimental results show that the average carbon emission intensity of measure A cities is 0.72 tons / yuan, 0.02 tons / 0,0.04 tons / yuan less than measures B and C; the average CE efficiency of measures A cities is 0.85,0.02 and 0.05 compared with measures B and C respectively. From the above data, adjusting the industrial structure can effectively improve the CE efficiency of various cities, reduce the CE, reduce the CE intensity, and promote the realization of CE reduction in cities.

Synergistic Effects of Organic Ligands and Visible Light on the Reductive Dissolution of CeO2 Nanoparticles: Mechanisms and Implications for the Transformation in Plant Surroundings.

Cerium oxide (CeO2) nanoparticles are one of the most important engineered nanomaterials with demonstrated applications in industry. Although numerous studies have reported the plant uptake of CeO2, its fate and transformation pathways and mechanisms in plant-related conditions are still not well understood. This study investigated the stability of CeO2 in the presence of organic ligands (maleic and citric acid) and light irradiation. For the first time, we found that organic ligands and visible light had a synergistic effect on the reductive dissolution of CeO2 with up to 30% Ce releases after 3 days, which is the highest release reported so far under environmental conditions. Moreover, the photoinduced dissolution of CeO2 in the presence of citrate was much higher than that in maleate, which are adsorbed on the surface of CeO2 through inner-sphere and outer-sphere complexation, respectively. A novel ligand-dependent photodissolution mechanism was proposed and highlighted: upon electron-hole separation under light irradiation, the inner-sphere complexed citrate is more capable of consuming the hole, prolonging the life of electrons for the reduction of Ce(IV) to Ce(III). Finally, reoxidation of Ce(III) by oxygen was observed and discussed. This comprehensive work advances our knowledge of the fate and transformation of CeO2 in plant surroundings.

A novel saponification process developed by the extraction and reduction of Ce(IV) from nitrate solution

Traditional saponification methods lead to large amounts of alkali consumption and saline wastewater discharge. Herein, a novel saponification strategy was proposed via the extraction and reduction of Ce(IV) in nitrate solution. Several key parameters were investigated to explore the influence on extraction and reduction. The results showed that the concentration of NO3- and acidity had insignificant influence on the extraction, indicating that Ce(IV) could be effectively extracted without saponification even in highly acidic solution. The theoretical amount of H2O2 was selected for the reduction process, and the corresponding reduction rate was nearly 99 %. The concentration of Ce(III) in the reductive organic phase was 0.15 mol/L, and the extraction rate of Yb(III) was up to 84.62 % for one-stage extraction. The extraction and reduction mechanisms were established using the slope method and FT-IR spectrometric analysis, and the complexes of the organic phase before and after reduction were determined. Based on the new saponification strategy and the circulation of Ce and nitrate, the alkali consumption and wastewater discharge would be avoided thoroughly.

Studies on Electrochemical Properties of Polycarbazole Prepared Via Self-Support Polymerization and Self-Doping

Mixed glassy zirconium-tin phosphate, g-Zr0.64.Sn.0.36(HPO4)2.3H2O(g-ZrSnP), nano fibrous cerium phosphate, Ce(HPO4)2 2,9H2O(nCePf), and mixed glassy zirconium-tin phosphate / fibrous cerium phosphate nanocomposite membrane, [g-Zr0.64 Sn0.36 (HPO4)2]0.25 [Ce(HPO4)2]0.75 ..4.43H2O, were prepared and characterized. By chemical , x-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform spectroscopy (FTIR), Zirconium tin mole ratio were estimated using (EDAX). Novel [g-Zr0.64 Sn0.36 (HPO4)2]0.25 [Ce(HPO4)2]0.75 / polycarbazole nanocomposite membrane was prepared via self-support polymerization of carbazole, which was promoted by the reduction of Ce(iv) phosphate present in the inorganic matrix. Possible explanation is nCePf present on the surface of the nanocomposite is attacked by carbazole, converted to cerium (III) orthophosphate(CePO4). The resultant polycarbazole was characterized by C,H,N analysis, SEM ,FT-IR. UV-Vis and electrical conductance measurements. From elemental (C,H,N) analysis, the amount of polycarbazole present in the composite found to be (2.15 % in wt.). Polycarbazole is considered as one of modern material used in solar cells, furthermore it has become an important material for optoelectronic applications in recent years. The dc conductivity of polycarbazole nanocomposite membrane at 280C (using RC-Circuit) found to be equal to 3x10-5 Scm-1, range of semi-conductors. We suggest self-doping occurred on polymerization, which is due to H+ present in (O3POH)2 groups of [g-Zr0.64 Sn0.36 (HPO4)2]0.25. The electrochemistry of resultant polycarbazole in acetonitrile solution for a range of concentrations from 1.06 x10-4 to 2.19 x 10–3 mol dm-3 was carried out using CV techniques. Investigation of its electrochemical properties affords insight into the mechanisms for their oxidation and reduction, therefore provides the basis for evaluating the stabilities of the material and for designing novel polycarbazole-derived materials with desired properties as well as new devices. That will be discussed.

Synthesis, Crystal Structure, and Photocatalytic Properties of Two Isoreticular Ce(IV)-MOFs with an Infinite Rod-Shaped Inorganic Building Unit.

The use of the V-shaped linker molecules 4,4'-oxydibenzoic acid (H2ODB) and 4,4'-carbonyldibenzoic acid (H2CDB) led to the discovery of two isoreticular Ce(IV)-based metal-organic frameworks (MOFs) of composition [CeO(H2O)(L)], L = ODB2-, CDB2-, denoted CAU-58 (CAU = Christian-Albrechts-University). The recently developed Ce-MOF synthesis approach in acetonitrile as the solvent proved effective in accessing Ce(IV)-MOF structures with infinite rod-shaped inorganic building units (IBUs) and circumventing the formation of the predominantly observed hexanuclear [Ce6O8] cluster. For the structure determination of the isoreticular MOFs, three-dimensional electron diffraction (3D ED) and powder X-ray diffraction (PXRD) data were used in combination with density functional theory (DFT) calculations. [CeO(H2O)(CDB)] shows reversible H2O adsorption by stirring in water and thermal treatment at 190 °C, which leads to a unit cell volume change of 11%. The MOFs feature high thermal stabilities (T > 290 °C), which exceed those of most Ce(IV)-MOFs and can be attributed to the infinite rod-shaped IBU. Surface and bulk oxidation states of the cerium ions were analyzed via X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES). While Ce(III) ions are observed by the highly surface-sensitive XPS method, the bulk material contains predominantly Ce(IV) ions according to XANES. Application of the MOFs as catalysts for the catalytic degradation of methyl orange in aqueous solutions was also studied. While degradation activity for both MOFs was observed, only CAU-58-ODB revealed enhanced photocatalytic activity under ultraviolet (UV) light. The photocatalytic mechanism likely involves a ligand-to-metal charge transfer (LMCT) from the linkers to the Ce(IV) centers. Analyses by XANES and inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrate that leaching of Cerium ions as well as partial reduction of Ce(IV) to Ce(III) takes place during catalysis. At the same time, PXRD data confirm the structural stability of the remaining MOF catalysts.