Cerium Phosphate Research Articles

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.

Microwave-Assisted Hydrothermal Synthesis of Ceric-Ammonium Phosphates (NH4)2Ce(PO4)2⋅H2O and NH4Ce2(PO4)3

The possibility of preparation of crystalline double cerium(IV) phosphates (NH4)2Ce(PO4)2⋅H2O and NH4Ce2(PO4)3 under the conditions of microwave-assisted hydrothermal synthesis has been analyzed. It has been shown that these phosphates in a single-phase state can be obtained in the temperature range of 130–190°С with a synthesis duration of ≥5 min, while the phase composition of the synthesis products is determined by the molar ratio of ammonia and phosphoric acid in the reaction mixture. Short-term (5 min) low-temperature (130°С) hydrothermal synthesis under microwave heating leads to the preparation of (NH4)2Ce(PO4)2⋅H2O and NH4Ce2(PO4)3 with a particle size of ~70 and ~200 nm, respectively. At higher temperatures and treatment times (190°C and 24 h), the particle size of these phases increases to ~200 and ~500 nm, respectively. For the first time, the value of the optical band gap for (NH4)2Ce(PO4)2⋅H2O was determined to be 2.8 and 3.1 eV for indirect and direct transitions, respectively.

Study on CePO4 modified PANI/RGO composites to enhance the anti-corrosion property of epoxy resin

This manuscript presents a modification method by using nanofillers for simultaneously improving the barrier and corrosion inhibition in epoxy coatings. In this method, polyaniline (PANI) nanofibers are first grown on reduced graphene oxide (RGO) using an in situ polymerization reaction, and then cerium phosphate (CePO4) nanograins are directly modified onto polyaniline/reduced graphene oxide (PANI/RGO) composites using a hydrothermal reaction. A new hydrophobic and corrosion-resistant PANI/RGO/CePO4 nanocomposite is successfully prepared. Physical and chemical characterization was performed by Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM). PANI/RGO/CePO4 nanomaterials were compounded into epoxy resin and sprayed on Q235 carbon steel, and their corrosion resistance performance was tested by using AC impedance spectroscopy and salt spray tests. The results show that PANI/RGO/CePO4 nanocomposites improve the barrier properties of epoxy resin. In addition, X-ray photoelectron spectroscopy (XPS) before and after corrosion showed that the cerium ions and phosphate ions released from CePO4 in the composite had a corrosion inhibition effect. It forms cerium oxide and iron phosphate corrosion inhibition films on mild steel and cuts off direct contact between the electrolyte and the substrate. This nanomaterial-loaded epoxy coating can greatly improve the composite's anti-corrosion ability.

Structure and properties of cerium phosphate and silicophosphate glasses

AbstractWe report on the fabrication, properties, and structure of cerium pyrophosphate glasses and partially substituted cerium silicophosphates. In those glasses, cerium occurs predominantly as Ce(III). A combination of dynamic nuclear magnetic resonance and electrical impedance spectroscopy is used to overcome the problem of assessing cerium speciation. While optical spectroscopy is unable to quantify the ratio of Ce(III)/Ce(IV) due to spectral overlap, proxy observations of the effect of silica‐for‐cerium substitution on optical extinction and the shape and width of the UV band gap corroborate vibrational spectroscopic data of the structural roles of cerium and silica. While silica bonding to phosphate units appears to stabilize Ce(IV), it also impedes the polaron transport, leading to higher polaron activation energy and lower electronic conductivity. On the other hand, Ce(III) is stabilized by coordinating to P = O.

Adsorption of UO 22+ on Fibrous Cerium Phosphate and its Alanine and Arginine Intercalated Materials

Amorphous fibrous cerium (IV) phosphate (f-CeP) was prepared and characterized. Batch sorption method was performed to investigate uptake of uranyl ion (UO2)2+ aqueous solution by amorphous fibrous cerium phosphate f-CeP, using different variables in order to elucidate its applicability as a uranium sorption medium. Sorption of Uranyl ions was measured spectrophotometically after its extraction by 8-hydroxy quinoline, implementing best adsorption conditions (pH, contact time, ionic strength, amount of adsorbent, and initial uranyl ion concentration) for estimation. Exchange capacity of f-CeP was 4.25meq/g. Its x-ray powder diffraction pattern showed an amorphous material with d001 spacing value of 10.76 Å. While its amino acid intercalates showed a significant increase in the d001 to 11.33Å for f-CeP / alanine and 14.19Å for f-CeP / arginine. From spectrophotometric analysis, the results showed that the maximum uranyl ion adsorption capacity reached the initial concentration of 50ppm, pH 4.5, contact time 3hrs and adsorption dosage of 2 g/L. However, amino acid intercalates showed less adsorption efficiency than their parent analogue.

Investigation of Intensity Dependent Nonlinear Absorption in Cerium Phosphate Nanorods

Cerium Phosphate (CePO4) is a material that has attracted attention because of its unique properties, redox capabilities, and a wide variety of applications. Cerium Phosphate nanoparticles with a nanorod structure were successfully synthesized by a hydrothermal synthesis procedure using Cerium Nitrate Hexahydrate (Ce (NO3)3.6H2O) and Diammonium Hydrogen Phosphate ((NH4)2HPO4) as the precursors without adding any surfactants. The synthesized CePO4 nanorods were characterized using X-ray Powder Diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis which showed pure monoclinic nanorod structures. The linear absorption was analyzed by UV-visible absorption spectrometry. The nonlinear absorption was measured by the open aperture Z-scan technique using a Q switched Nd-YAG laser at 532nm. The Z-scan curve exhibited reverse saturable absorption. In this study, the dependence of nonlinear absorption of CePO4 on the intensity of incident light was investigated. The non-linear absorption coefficient was measured and it was found that the non-linear absorption decreased with the increasing intensity.

Novel Intense Red Emitting Eu3+ Doped CePO4 Nanocrystals for Solid State Lighting Applications

Novel red emitting europium doped Cerium phosphate nanocrystals were synthesized by microwave assisted sol gel method. X-ray powder diffraction analysis identified the monoclinic structure of synthesized samples. The morphology of the samples were found to beconstructed from elongated spheres and is explained with the help of TEM analysis. Intense orange red emission on excitation with Ce4+ - O2-charge transfer band is established by photoluminescence analysis. The effect of annealing on the efficiency of excitation with Ce4+ - O2-charge transfer band is demonstrated and is explained in association with the concentration of surface Ce4+. Chromaticity coordinates indicate good colour purity of the sample. All the results indicated that microwave assisted method is suitable for synthesizing red emitting CePO4:Eu phosphors and become a potential candidate for optoelectronic and biological applications.

Ce-MOFs derived cerium phosphate for high-efficiency electrochemical detection of metronidazole

In this work, three kinds of cerium phosphate (CePO4) with different morphologies, namely rod-like CePO4 (R–CePO4), spherical CePO4 (S–CePO4), and platelike CePO4 (P–CePO4), were successfully hydrothermally synthesized by using Ce-MOFs (MOF ​= ​metal-organic framework) as templates. The CePO4 materials synthesized by this method not only retain the morphology of Ce-MOFs, but also possess good crystallinity and high specific surface areas, suggesting the universality of this method. Among them, the S–CePO4 modified glassy carbon electrode (S–CePO4@GCE) shows the highest electrochemical activity. When S–CePO4@GCE was used to detect metronidazole (MNZ), a wide linear range of 5.0–3980 ​μM, a low detection limit (S/N ​= ​3) of 3.6 ​μM, good stability, and high selectivity could be obtained. This may be due to the good redox properties of cerium, the higher specific surface area of mesoporous S–CePO4, and the hydrogen bonding interactions between S–CePO4 and MNZ. In addition, the constructed electrode S–CePO4@GCE can also be used for analyzing MNZ in the real medicines and the water samples. This work provides a useful method to prepare high-efficiency CePO4-based electrode materials.

γ-Zirconium Titanium-Phosphates – Fibrous Cerium Phosphate / Polyaniline, Polyindole, Polycarbazole and Polyimidazole Nanocomposite Membranes

Layered nanosized mixed γ-zirconium titanium phosphates and fibrous cerium phosphate, γ-ZrxTi(1-x)..PO4.H2PO4.2H2O (γ-ZTP), Ce(HPO4)2.2.9H2O(nCePf), respectively, (x= 0.95, 0.89), and their [γ-ZrxTi(1-x).PO4. H2PO4]0.3 [Ce(HPO4)2]0.70. 2H2O nanocomposite membranes were prepared and characterized by chemical, x-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform spectroscopy (FT-IR). Novel [γ-ZrxTi(1-x).PO4.H2PO4]0.3[Ce(HPO4)2]0.70 /polyaniline, polyindole, polycarbazole, and polyimidazole nanocomposite membranes were prepared via in-situ chemical oxidation of the monomers aniline, indole, carbazole and imidazole, respectively, that was promoted by the reduction of Ce(IV) ions present on the surface of the inorganic matrix composite. A possible explanation is nCePf occurs at the surface of the composite was attacked by the monomers, respectively, converted to cerium (III) orthophosphate (CePO4). The resultant novel composites were characterized by elemental (C,H,N) analysis and FT-IR. From elemental (C,H,N) analysis the % in weight of the resultant conducting polymers present in [γ-Zr0.95Ti0.05.PO4.H2PO4]0.3 [Ce(HPO4)2]0.70 composite were [ Pani 19.35, PIn 5,72. PCz 5.8, PIm 23.7]%. The % in weight of the conducting polymers in the composite [γ-Zr0.9Ti0.11.PO4.H2PO4]0.3[[Ce(HPO4)2]0.70 were [Pani 8.54, PIn 8.02, PCz 7.72, PIm 22.27]%. The conductivity of the resultant conducting polymers found to be in the range of semiconductors.

Bifunctional CePO4/CeO2 nanocomposite as a promising heterogeneous catalyst for the enhancement of the ozonation recovery effect in the presence of chloride ions

The degradation of organics through ozonation is strongly reduced by chloride ions. Although the efficiency of such processes can be recovered in the presence of homogeneous phosphates, the addition of these chemicals to water is problematic because of the generation of secondary wastes. Phosphates are known as one of the most important biogens responsible for the eutrophication of rivers and lakes. Thus, their worldwide application should be limited. The main goal of this work was to characterize the performance of solid-state cerium(III) phosphate (CePO4), cerium dioxide (CeO2), and bifunctional CePO4/CeO2 nanocomposite as substitutes for homogeneous phosphates during the ozonation of benzoic acid (BA) in the presence of chlorides. All solid-state samples used in this study were synthesized by facile hydrothermal method and thoroughly characterized. It was documented that heterogeneous CePO4 showed significantly better ozonation recovery effect than homogeneous phosphates. It was also established that the process efficiency could be further enhanced by using the bifunctional nanocomposite. Tests with the use of tert-butanol as a hydroxyl radical scavenger revealed that the improved ozonation efficiency in the presence of CePO4/CeO2 resulted from the action of HO• radicals which were the key reactive oxygen species responsible for the recovery of BA degradation in the presence of chlorides.

Efficient degradation of emerging organic pollutant by cerium phosphate/g-C3N4/Vis/PMS system: Catalytic kinetics and toxicity evaluation

The Cerium Phosphate (CP) doped g-C3N4(g-CN) composite was synthesized by a simple hydrothermal process. The crystal nature, absorbance, morphology, elemental analysis, functional groups analysis, charge and particle size of all the synthesized materials were examined by various characterization techniques like UV − Vis-DRS spectroscopy (UV–Vis),Fourier transform infra red spectroscopy analysis (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy techniques (TEM), zeta potential and particle size analyser. The characterized CP/g-CN composite was used as a photocatalyst for the degradation of malachite green (Mal G) dye under the visible light irradiation with peroxymonosulfate (PMS) activation. The composite material was found to successfully overcome the electron hole recombination process. The PMS activation process was used to enhance the photocatalytic efficiency of the synthesized CP/g-CN composite. The synthesized CP/g-CN with PMS activation exhibits 94% of malachite green dye degradation in time duration of 90 min and also was found to retain 90% of degradation efficiency after four consecutive photocatalytic performances. The toxicity of the photocatalytic degraded water sample was examined by the animal and plant mortality studies. The zebra fish (Danio rerio) and Mung bean (Vigna radiata) were employed in the animal and plant survival investigations. The CP/g-CN photocatalyst treated dye solution is found to be fit for animal and plant survival and therefore it is a potential photocatalyst for water remediation application.

Study on the mechanism of rapid formation of ultra-thick tribofilm by CeO2 nano additive and ZDDP

CeO2 nanoparticles are potential anti-wear additives because of their outstanding anti-wear and load-bearing capacity. However, the shear-sintering tribo-film formation mechanism of oxide nanoparticles limits the tribo-film formation rate and thickness greatly. In this study, by compounding with zinc dioctyl dithiophosphate (ZDDP), ultra-fine CeO2 nanoparticles modified with oleylamine (OM) can quickly form 2 µm ultra-thick tribo-film, which is 10–15 times thicker than that of ZDDP and CeO2, respectively. The ultra-thick tribo-film presents a nanocomposite structure with amorphous phosphate as binder and nano-CeO2 as filling phase, which leads to the highest loading capacity of composite additives. The results of adsorption experiments tested by dissipative quartz crystal microbalance (QCM-D) showed that the PB value of additive has nothing to do with its equilibrium adsorption mass, but is directly proportional to its adsorption rate in 10 s. The compound additive of CeO2 and ZDDP presented the co-deposition mode of ZDDP monolayer rigid adsorption and CeO2 viscoelastic adsorption on the metal surface, which showed the highest adsorption rate in 10 s. It is found that the tribo-film must have high film forming rate and wear resistance at the same time in order to achieve super thickness. Cerium phosphate was formed from ZDDP and CeO2 through tribochemistry reaction, which promotes the formation of an ultra-thick tribo-film with nanocomposite structure, which not only maintains the low friction characteristics of CeO2, but also realizes high PB and high load-carrying capacity.

The way to increase the monovalent ion selectivity of FujiFilm® anion-exchange membranes by cerium phosphate modification for electrodialysis desalination

Recently, the selectivity of ion-exchange membranes and its control have been the subject of numerous fundamental and applied studies. This paper reports an enhanced monovalent anion selectivity of hybrid membrane based on the FujiFilm® Type I anion-exchange membrane and in situ synthesized cerium phosphate (CeP) with a gradient distribution over the membrane thickness. The Cl/SO4-selectivity coefficient (P(Cl/SO4)) of hybrid membranes reached 6.2. The effect of modification on the Cl/SO4 selectivity passed through a minimum as the total concentration of the external solution increased from 0.04 M to 1 M. For low concentration electrolytes, Cl/SO4-selectivity improving was attributed to partial neutralization of positive fixed charges by negative fixed charges of cerium phosphate, which causes an effective decrease of ion-exchange capacity and reduction of electrostatic selectivity factor favouring sulfate transport; for high concentration electrolytes, to the formation of narrow transport channel between the surface of the inorganic nanoparticle and the pore wall, which causes a decrease of sulfate transport due to the size sieving effect. The hybrid membranes and cerium phosphate were characterized using ATR FTIR and 31P MAS NMR spectroscopy, XRD analysis and scanning electron microscopy with EDX microanalysis.

Au modified spindle-shaped cerium phosphate as an efficient co-reaction accelerator to amplify electrochemiluminescence signal of carbon quantum dots for ultrasensitive analysis of aflatoxin B1

In various detection methods of aflatoxin B1 (AFB1), false positives and false negatives are common due to the low sensitivity, expensive equipment or improper pretreatment during operation. Here, a sandwich electrochemiluminescence (ECL) immunosensor armed with a synergistic co-reaction acceleration strategy was employed for the ultra-sensitive detection of AFB1. Benefiting from the catalytic properties of Ce3+/Ce4+ redox pairs, cerium phosphate@gold (CePO4@Au), for the first time, was introduced into the immunosensor as a new type of co-reaction accelerator, and it significantly improved the ECL intensity of the nitrogen doped hydrazide conjugated carbon dots (NHCDs)-H2O2 system. CePO4@Au has the ability to promote the decomposition of H2O2 and accelerate the formation of O2•−. The more of O2•− reacts with NHCDs to produce a stronger and more robust ECL signal response. Furthermore, the spindle-shaped sensing interface formed by oxidation cerium and phosphate has a high loading area and good biocompatibility, and the modification of Au nanoparticles further achieves the stable binding of the capture antibody. Striving for further improvement, Ag modifies Barium titanate (BaTiO3), as the signal carrier with amplification ability, loads with a large number of anodic luminescent carbon quantum dots, were adopted as detection markers for the construction of sandwich ECL biosensors. The co-reaction amplification system achieves high precision quantitative detection of AFB1 in the linear range of 0.01 pg/mL–100 ng/mL, and the detection limit is 9.55 fg/mL. In addition, the constructed biosensor also showed good stability, reproducibility and specificity, with a promising application prospect.

Amorphous and crystalline cerium(IV) phosphates: biocompatible ROS-scavenging sunscreens.

This paper reports on a comprehensive study of the UV-shielding properties (namely, the sun protection factor and the factor of protection against UV-A radiation) and cytotoxicity (including photocytotoxicity) of amorphous and crystalline cerium(IV) phosphates. It has been shown that cerium(IV) phosphate NH4Ce2(PO4)3 is characterised by UV-shielding properties that are comparable to those of nanocrystalline TiO2 and CeO2. Moreover, cerium(IV) phosphates did not show toxicity towards cell cultures of NCTC L929 line mouse fibroblasts and human mesenchymal stem cells, in a wide range of concentrations, and even enhanced the proliferative activity of the latter. In a model study of the photoprotective properties of cerium(IV) phosphates on human mesenchymal stem cells, the pronounced protective effect of NH4Ce2(PO4)3 was observed, which was comparable to the shielding action of nanocrystalline CeO2. The results have shown that tetravalent cerium phosphates can be considered as promising UV-filters for sunscreen applications.

Solubilization of struvite and biorecovery of cerium by Aspergillus niger

Cerium has many modern applications such as in renewable energies and the biosynthesis of nanomaterials. In this research, natural struvite was solubilized by Aspergillus niger and the biomass-free struvite leachate was investigated for its ability to recover cerium. It was shown that struvite was completed solubilized following 2 weeks of fungal growth, which released inorganic phosphate (Pi) from the mineral by the production of oxalic acid. Scanning electron microscopy (SEM) showed that crystals with distinctive morphologies were formed in the natural struvite leachate after mixing with Ce3+. Energy-dispersive X-ray analysis (EDXA), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of cerium phosphate hydrate [Ce(PO4)·H2O] at lower Ce concentrations and a mixture of phosphate and cerium oxalate decahydrate [Ce2(C2O4)3·10H2O] at higher Ce concentrations. The formation of these biogenic Ce minerals leads to the removal of > 99% Ce from solution. Thermal decomposition experiments showed that the biogenic Ce phosphates could be transformed into a mixture of CePO4 and CeO2 (cerianite) after heat treatment at 1000 °C. These results provide a new perspective of the fungal biotransformation of soluble REE species using struvite leachate, and also indicate the potential of using the recovered REE as biomaterial precursors with possible applications in the biosynthesis of novel nanomaterials, elemental recycling and biorecovery.Key points• Cerium was recovered using a struvite leachate produced by A. niger.• Oxalic acid played a major role in struvite solubilization and Ce phosphate biorecovery.• Resulting nanoscale mineral products could serve as a precursor for Ce oxide synthesis.

Two-phase synthesis of Fe doped cerium phosphate ultra-fine nanocrystals for efficient oxygen evolution

An enhanced OER catalyst based on Fe doped CePO4 exhibits higher turnover frequency, more active sites and more oxygen vacancies than CePO4.

A blue arsenomolybdic acid-crystal violet ion-associate pair paving the way for the field detection of arsenic in groundwater.

A simple visual colorimetric method based on arsenomolybdic acid-crystal violet ion-associate pair formation is described for the detection of As in groundwater at about 10, 25 and 50 μg L-1 levels. The pair exhibits light green coloration at ≤5 μg L-1 and blue colorations of distinctly different intensities at about 10, 25 and 50 μg L-1 concentrations of arsenic. High sensitivity is achieved by the preconcentration of As that entails simultaneous sorption of both As(III) and As(V) from groundwater on covellite (CuS) and, later, their elution as As(V), which subsequently participates in the formation of arsenomolybdic acid. The interference in the color development from PO43-ions that are as efficiently sorbed on CuS and eluted as the oxyanions of As is eliminated by their selective removal by Ce4+ ions under basic (pH ∼ 8.5) conditions. The removal is caused by the formation of cerium phosphate and its co-precipitation with calcium hydroxide. SiO42- ions do not interfere in the process as they are not sorbed by CuS. Groundwater containing ≤0.5 mg L-1 P and ≥200 mg L-1 total dissolved solid can be conveniently analysed by the method. The direct sensing of As(III) as well as As(V), the use of benign and easily available chemicals, the absence of any hazardous by-product, undiminished applicability in sunlight, the testing procedure lasting only for about 30 min, and rapidity are the major advantages of the method. Thus, the method is potentially well-suited for the on-site testing of groundwater potability under different regulations.

Brønsted acid enhanced hexagonal cerium phosphate for the selective catalytic reduction of NO with NH3: In situ DRIFTS and DFT investigation

The possible effect of optimized acid sites on NH3-SCR performance and the fundamental mechanism are barely illustrated. In this work, we report two model catalysts of hexagonal (h-CPO) and monoclinic (m-CPO) cerium phosphate with disparate acidity that show different NH3-SCR activities under the same reaction conditions. Brønsted acid sites were found to be crucial for NH3-SCR performance at both low and high temperature. The electron localization discrepancy of h-CPO was more pronounced as compared with m-CPO, leading to the enrichment of P-OH (Brønsted acid site) which could strongly absorb NH3 and then generate NH4+ to participate in fast SCR via Langmuir-Hinshelwood mechanism, resulting in good activity at low temperature. The zeolitic water stored in the open channels of h-CPO could be released as supplement for P-OH sites which prevent the depletion and non-selective oxidation of NH3 thus maintaining its high activity at high temperature via the Eley-Rideal mechanism. Meanwhile, as DFT calculation revealed, cerium is the electron deficient center which can easily fix NO and NO2 from the intake, generating active NO2(ad) or nitrites and facilitating fast SCR by reacting with NH4+ species. Hence, the superior protonation ability to form P-OH and low energy barrier to generate active nitrites of h-CPO led its T80 NOx conversion to a broaden temperature of 150–450 oC under high GHSV of 177,000 h-1. Furthermore, experimental and DFT calculation also demonstrated that the enriched Brønsted acid sites over h-CPO have largely suppressed SO2 adsorption, thus significantly reducing the formation of metal sulfates and achieving great SO2 resistance. The ammonium sulfate deposits can be storage of NH3, supplying additional reductant to promote high temperature activity and selectivity.

Boosting Hydrogen Evolution Reaction via Electronic Coupling of Cerium Phosphate with Molybdenum Phosphide Nanobelts.

Molybdenum phosphide (MoP) is regarded as one of the most promising alternatives to noble-metal based electrocatalysts for efficient hydrogen evolution reaction (HER) due to its similar d-band electronic structure to noble metals and tunable features associated with phase and composition. However, it still remains a great challenge to construct MoP electrocatalysts with abundant active sites that possess ideal H binding strength to promote catalytic performance. In this work, it is found that by anchoring a rare earth compound, cerium phosphate (CePO4 ) on MoP (CePO4 /MoP), the stabilized Ce3+ in CePO4 can significantly boost the formation of oxygen vacancies in ceria (CeO2 ) in situ formed on CePO4 surface during HER, which effectively regulates the d-band electronic density-of-states of MoP, increases the numbers of active sites, and promotes the vectorial electron transfer, therefore greatly enhancing the HER performance of MoP. The optimized CePO4 /MoP/carbon cloth (CC) electrocatalyst exhibits a significantly improved HER performance with an overpotential of 48 mV at 10 mA cm-2 and a Tafel slope of 38 mV dec-1 , about two times better than the HER performance of MoP catalyst without CePO4 (with an overpotential >80 mV dec-1 at 10 mA cm-2 ), very close to commercial Pt/C catalyst.