Incorporation Of Ceria Research Articles

Production of synthesis gas from dry reforming of propane with carbon dioxide over ceria-promoted nickel foam catalysts

A series of nickel foam supported cerai catalysts (ceria/NiF) for dry reforming of propane with carbon dioxide were prepared and their performance were evaluated at temperatures in the range of 520-600°C. Among the catalysts examined the 4 wt.% CeO2/NiF exhibited better low-temperature activity for the DRP, which is attributed to the formation of well- isolated nanosize CeO2 particles and highly reducible metal oxide species over the NiF support. The XPS and temperature programmed reduction (TPR) data also supported the incorporation of ceria into the NiO surface layer formed over NiF support, which was substantially higher in 4% CeO2/NF catalyst. Due to these favorable properties, the 4 wt.% CeO2/NiF could be considered as an excellent catalyst for DRP.

Corrosion Behavior in Saline Solution of Electrodeposited Nanocomposite Zn-CeO2 Coatings Deposited onto Low Alloyed Steel

Zn-CeO2 nanocomposite coatings were deposited onto mild steel substrates by electrodeposition process. Our study highlights the effect of ceria nanoparticles embedded into a metallic matrix on the corrosion behavior in saline environment. The experimental results show that the ceria incorporation and dispersion depend on the particles concentration in the electrolyte. High concentrations of particles favor agglomeration and adsorption of agglomerates on the surface of the zinc coating. A slight improvement of the corrosion resistance compared to pure electrodeposited zinc coatings is observed. The beneficial effect seems to be dependent on the dispersion of the nanoparticles embedded inside the mela matrix. The distribution of nanoparticles seems to be the key-parameter influencing the corrosion behavior, permitting to improve the corrosion behavior during extended immersion test.

Coffee-waste templated CeOx/TiO2 nanostructured materials for selective photocatalytic oxidations

An environmentally friendly solvent-free approach was tested using spent coffee as a biomass sacrificial template for the preparation of TiO2 modified with CeOx. The use of coffee as a template pursues the preparation of a nanostructured heterojunction without the need for a solvent. Two variables were optimized in the synthesis process, i.e. calcination temperature and proportion of CeOx. Firstly, bare coffee-template titania was prepared to explore the effect of the calcination temperature, within 500–650 °C. The anatase phase was obtained up to 600 °C. Higher temperatures, i.e. 650 °C, led to the appearance of rutile (10%) and efficient removal of the sacrificial agent (0.6% residue). The maximum photocatalytic activity in terms of conversion, in the oxidation of benzyl alcohol, was achieved employing the bare coffee-template TiO2 at 650 °C, and it was found comparable to the benchmarked P25. The incorporation of ceria in the solvent-free approach considerably improved photocatalytic benzaldehyde production. No changes in the XRD pattern of TiO2 were appreciated in the presence of ceria due to the low amount added, within 1.5–6.0%, confirmed by XPS as superficial Ce3+/Ce4+. The UV–visible absorption spectra were considerably redshifted in the presence of Ce, reducing the bandgap values of bare titania. An optimum amount of ceria in the structure within 3-0% was found. In this case, the selectivity towards benzaldehyde was ca. 75%, 3 times higher than the selectivity value registered for the benchmarked P25 or the bare prepared TiO2.

The bulk and supported perovskite-type catalysts for the CO2 reforming of methane: The effect of ceria and magnesia

BackgroundThe bulk or supported nickel catalysts are active in the dry reforming of methane to produce syngas. The nickel-based catalysts are deactivated quickly due to the metal sintering and coke deposition. Perovskite catalysts are stable, enhance the dispersion of the active sites, and resist metal sintering and coke deposition. The coke deposition is inhibited by increasing the CO2 adsorption and oxidation of the deposited coke. MethodsA series of ceria-doped perovskite catalysts La1-xCexNiO3, LaNi1-xCexO3 and magnesia-modified-alumina supported perovskite-type catalysts were prepared via the sol-gel method. The prepared catalysts were thoroughly characterized via state-of-the-art characterization techniques. Significant findingsThe incorporation of ceria assisted the supported catalysts in forming a dispersed phase at low loading and forming other NiO or NiO-MgO (solid solution) NiAl2O4 and MgAl2O4 (spinel phase). The catalytic activity for the CO2 reforming of methane reaction increased with the addition of magnesia and the substitution of La-ion with tetravalent metal cation (ceria). The doping of ceria increased the stability of the catalyst. The bulk catalyst La0.5Ce0.5NiO3 exhibited promising catalytic activity. The magnesia-modified-alumina-supported catalyst (50La0.5Ce0.5NiO3/8MgO-Al2O3) was more active than the alumina-supported or bulk-perovskite catalysts with low coke deposition and higher percent conversion of CH4 (97%) and CO2 (99%) at 1073 K.

Trace amount of ceria incorporation by atomic layer deposition in Co/CoOx-embedded N-doped carbon for efficient bifunctional oxygen electrocatalysis: Demonstration and quasi-operando observations

As a promising class of alternatives to noble metal-based oxygen electrocatalysts, hybrids of metal/metal oxide (M/MO) and N-doped carbon have been widely explored. To address the often-insufficient catalytic activity of single M/MO-embedded N–C systems, researchers have introduced a second M/MO, usually via wet processes. In this work, we leverage the unique capability of atomic layer deposition (ALD) to enable the introduction of a trace amount of ceria throughout a Co/CoOx-embedded N-doped carbon nanostructure in a highly uniform and dispersed manner to maximize heterogeneous interfacial areas and thus catalytically active sites. An optimally prepared catalyst achieves an ORR onset potential of 0.95 V (0.1 M KOH) and an OER potential of 1.53 V at 10 mA cm−2 (1 M KOH) and exhibits excellent cyclic durability. Quasi-operando observations reveal the multifaceted roles of the tiny amount of introduced ceria in facilitating electrocatalytic activity and enhancing durability. The ceria activates reactant adsorbates and transfers the activated intermediates to neighboring CoOx and electronically couples with Co and N species for enhanced catalytic activity. A high concentration of trivalent Ce state is readily and continuously restored during ORR/OER for an uninterrupted activation of reactants, also contributing to a highly stable reaction.

Influence of CeO2 loading on the catalytic performance of CoNiMoS/CeO2–Al2O3 toward vacuum gas oil hydrotreatment

This work investigates the effect of CeO2 doping into the CoNiMoS/Al2O3 catalyst on the efficiency of heavy vacuum gas oil (HVGO) hydrotreatment. Particularly, two supports contain 10% and 25% CeO2 to Al2O3 were prepared by co-precipitation method. Metals were subsequently loaded onto these supports via impregnation technique. The produced catalysts had been then sulfided before introduction to the hydrotretment process. Structural characteristics of supports and catalysts were verified by X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), Transmission electron microscope (TEM) and N2-physiosorption technique. Obvious variations in both morphology and values of surface features could be detected via incorporation of ceria with alumina. The10%CeO2 doped catalyst could successfully attain high percentages of simultaneous hydrodesulfurization and hydrodenitrogenation affinity: 94.8% and 95.45% respectively. This increased the catalytic activity, which had been 30% higher than of using alumina individually, could be attributed to the presence of ceria within the composition of support.

Hydrothermally prepared Ag-CeZrO2 nanocomposite for efficient diesel soot oxidation

Air pollution caused by diesel soot emission, is a serious environmental issue. In order to prevent the soot being released into the atmosphere, the catalyzed combustion of the soot trapped in diesel particulate filter (DPF) is performed, normally at high temperature. Among different noble metal dopants, Ag is effective in decreasing the active temperature, which can catalyze graphitic oxidation by penetrating into bulk graphite. The optimum 5 wt% Ag loading in Ag-ZrO2NPs were reported earlier. In our previous study, we demonstrated the catalytic properties of Ag-ZrO2 nanoparticles (NPs) with optimum 0.9 wt% Ag loading, which showed its cost effectiveness when compared with the high cost of Ag noble metal. The catalytic oxidation peak position declined gradually 455 °C to 399 °C with corresponding sintered temperature from 400 °C to 800 °C respectively.In this study, further decrease in soot oxidation temperature (387 °C) was achieved by incorporating ceria into the Ag-ZrO2 system (Ag-CeZrO2). A facile hydrothermal synthesis method was utilized for preparation of Ag-CeZrO2 nanocomposites. After the incorporation of ceria to Ag-ZrO2 system, the tetragonal phase of ZrO2 was observed instead of multi phases (tetragonal and monoclinic) ZrO2. In the present study, the soot combustion behavior of Ag-ZrO2 and Ag-CeZrO2 catalysts is described in details..

Experimental and DFT investigation of ceria-nanocomposite decorated AC derived from groundnut shell for efficient removal of methylene-blue from wastewater effluent

Removal of dyes is a significant aspect of environmental remediation to ensure clean water and atmosphere. In this study, we report an incorporation of nano ceria at different weight loadings via solid state impregnation on the highly porous activated carbon (AC) derived from groundnut shell to form nano-ceria decorated AC for effective removal of cationic dye (methylene blue). The adsorption capacity of MB within a short period is highly remarkable with 199.76 mg/g, corresponding to 99.9% efficiency in 400 ppm using 40 mg weight adsorbent. The adsorbent at relatively low loadings (0.5–1%) of nano-ceria of AC favors significantly adsorption of MB, owing to the high degree of dispersion of cerium with improved textural properties, acidity and surface chemistry. The adsorbents were characterized by the N2-sorption, spectroscopies; (XRD, FTIR and Raman), microscopies (SEM and TEM) and temperature programmed desorption (TPD) techniques. The isotherm and kinetics information reveals that the adsorption mechanism of MB is elucidated by the Langmuir and pseudo-second order models, respectively. Quantum chemical DFT calculations revealed that ceria incorporation lowers the HOMO-LUMO energy gap (ΔE), increases the chemical softness and enhances the adsorption capacity of AC with a theoretical adsorption energy of −18.5 kcal/mol.

Effects of metal support interaction on dry reforming of methane over Ni/Ce‐Al2O3catalysts

AbstractDry (CO2) reforming of methane is conducted over two newly synthesized Ni20/Ce‐γAl2O3and Ni20/Ce‐meso‐Al2O3catalysts. The x‐ray diffraction (XRD) patterns indicated that Ni20/Ce‐meso‐Al2O3exhibits a better dispersion of nickel, while Ni20/Ce‐γAl2O3has larger amounts of nickel crystallites. The temperature programmed desorption (TPD) kinetics analysis indicated that Ni20/Ce‐meso‐Al2O3had a lesser metal‐support interaction than the Ni20/Ce‐γAl2O3. The thermal gravimetric analysis (TGA) indicated that the incorporation of ceria into the Al2O3matrix helps to stabilize Ni20/Ce‐meso‐Al2O3during dry reforming of methane. The temperature programmed reduction (TPR) indicated that the synthesized catalysts were sufficiently reducible below 750 °C. A fixed bed reactor evaluation (at 750 °C) showed that both catalysts can facilitate methane reforming to syngas with minimal coking throughout the 30 hours time‐on‐stream (TOS). However, Ni20/Ce‐meso‐Al2O3is more promising in terms of prolonged stability for dry reforming applications. Moreover, the syngas yield for Ni20/Ce‐γAl2O3is close to equilibrium prediction during the first 1 hour of reaction time.

Heteroepitaxial oxygen-buffering interface enables a highly stable cobalt-free Li-rich layered oxide cathode

Abstract The oxygen redox process plays an essential role for the high charge-discharge capacity in Li-rich layered oxide (LLO) cathodes. The irreversible release of lattice oxygen may lead to surface reconstruction and cathode-electrolyte interfacial reactions, transition metal (TM) dissolution, as well as microcrack evolution, etc. during cycling that limit the commercial application of LLO cathodes. Herein, we propose the design of a heteroepitaxial Fluorite(CeO2)@Rocksalt@Layered interface with oxygen buffering effects in Cobalt-free Li1.2Mn0.53Ni0.27O2 through the incorporation of ceria. Experimental characterization and theoretical calculations reveal that the fluorite CeO2 nanolayer with oxygen vacancies suppresses the irreversible lattice oxygen loss and cathode-electrolyte interfacial reactions in LLOs. Moreover, the synergy involving the formed rocksalt interphase and Ce3+ doping in the bulk not only stabilizes the structural integrity, resulting in substantial enhancement of capacity/voltage retention, but also accelerates the electrochemical kinetics upon cycling. This finding may pave the path for utilizing the reversible oxygen redox process and designing new high capacity TM-oxide cathode materials.

The synthesis of monodispersed M-CeO2/SiO2 nanoparticles and formation of UV absorption coatings with them.

CeO2/polymer nanoparticles have drawn considerable attention for their excellent UV absorption properties. However, many challenges still exist in the successful incorporation of ceria into the polymer matrix for the easy agglomeration and photocatalytic activity of CeO2 nanoparticles. Herein, we address these issues by constructing three-layer structured nanoparticles (M-CeO2@SiO2) and incorporating them into a polymer matrix through a mini-emulsion polymerization process. During this process, small-sized nano-ceria became uniformly anchored on the surfaces of monodisperse silica particles first, and then the particles were coated with an MPS/SiO2 shield. The morphology and dispersion of the nanoparticles were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The performance of the hybrid films was characterized using UV-vis absorption spectroscopy (UV-vis) and water contact angle (WCA) measurements. Results showed that the M-CeO2@SiO2 nanoparticles exhibited a three-layer structure with a mean diameter of 360 nm, and they possess good compatibility with acrylic monomers. After the addition of M-CeO2@SiO2, hybrid films exhibited enhanced UV absorption capacity as expected, accompanied by an obvious improvement in hydrophobicity (the water contact angle increased from 84.2° to 98.2°). The results showed that the hybrid films containing M-CeO2@SiO2 particles possess better global performance as compared with those containing no particles.

H2 permeation increase of electroless pore-plated Pd/PSS membranes with CeO2 intermediate barriers

This work presents the improvement of hydrogen permeance on electroless pore-plated Pd-composite membranes by the incorporation of ceria as intermediate barrier. This modification, in case of preparing a thick barrier, reduces both average pore size and external roughness of an oxidized Porous Stainless Steel (PSS) tube used as support. However, it also provokes a marked reduction of its permeance, turning more difficult the pass of the hydrazine through the modified support and, therefore, the palladium incorporation by electroless pore-plating. An optimization of this process leads to a Pd/CeO2/PSS composite membrane in which the initial roughness is halved, achieving a stable and selective Pd layer of around 15 μm. This composite membrane exhibits a hydrogen permeance of 5.37 · 10−4 mol m−2 s−1 Pa−0.5 at 400 °C, an ideal H2/N2 perm-selectivity ≥10,000 and an activation energy of 8.9 kJ mol−1. Moreover, the hydrogen flux increases around 400% with regard to previous results, in which no ceria was used as intermediate layer (measured range: 0.03–0.12 mol m−2 s−1 versus 0.01–0.03 mol m−2 s−1). This increase is derived from a high reduction, of around 30%, in the resistance to the permeation process when using electroless pore-plated membranes due to a lower penetration grade of the Pd external film into the support. In addition, it has been confirmed the successfully stability of the Pd membrane under thermal cycles and different operating conditions, including the variation of permeate flux direction from the inner to the outer of the membrane, where the Pd-layer is placed, or vice versa.

Nanoceria induced grain refinement in electroless Ni-B-CeO2 composite coating for enhanced wear and corrosion resistance of Aluminium alloy

Nickel-based coatings on aluminium with specific surface properties are of great interest for anti-corrosive, anti-wearing, and self-lubricating applications. In the present study electroless Ni-B alloy and Ni-B-CeO2 nanocomposite coatings were formed on 356 aluminium alloy surfaces. Ceria incorporation to Ni-B coating reduces the average nodular grain size from 1150 nm to 650 nm and Ni crystallite size from 15 nm to 9.97 nm. Ni-B-CeO2 nanocomposite shows remarkable improvement in microhardness of 684 VHN compared to pure Ni-B coating with 424 VHN. Enhanced wear resistance and reduction in friction coefficient are observed for the nanocomposite coatings compared to 356 Al alloy and Ni-B alloy coating. Potentiodynamic polarization measurements show a remarkable reduction in the corrosion current density for ceria added nanocomposite coating (2.48 × 10−6 A cm−2) than that of the particle-free counterpart (11.18 × 10−6 A cm−2). Uniform Ni-B-CeO2 composite coating was obtained on centrifugally cast A356 aluminium alloy cylinder liners which have potential applications in automotive systems.

Effect of the Presence of Ceria in the NSR Catalyst on the Hydrothermal Resistance and Global DeNOx Performance of Coupled LNT–SCR Systems

The global performance of coupled LNT–SCR systems, addressed to high NOx-to-N2 conversion, minimal ammonia slip and null N2O production, as well as the hydrothermal resistance of single NSR and SCR monolith catalysts and their coupling is discussed. Pt–Ba/Al2O3 and Pt–Ce–Ba/Al2O3 were washcoated on cordierite monoliths as NSR catalysts, and Cu/CHA was washcoated on similar monoliths as SCR catalysts. Both monoliths were coupled in two subsequent reactors to conform the LNT–SCR system. Previously to washcoating, the fresh powder catalysts and after severe hydrothermal aging were fully characterized by N2 adsorption–desorption isotherms at 77 K, X-ray diffraction, NH3 temperature-programmed desorption, and H2 chemisorption to relate textural and chemical characteristics with the DeNOx performance. The Cu/CHA catalyst shows an excellent hydrothermal resistance for the NH3–SCR reaction. Incorporation of ceria to the model Pt–BaO/Al2O3is beneficial for the NO-to-NOx oxidation and NO2 storage, improving NO conversion at low temperature and reducing the NH3 slip. However, addition of ceria is detrimental for the hydrothermal resistance of the NSR catalyst. However, this detrimental effect is minimized when the NSR catalyst is coupled with the Cu/CHA monolith downstream of the NSR catalyst, achieving the coupled LNT–SCR device high NO conversion and minimal NH3 slip with superior N2 selectivity for an extended temperature windows, including as low as 220 °C, and maintaining performance even after severe hydrothermal aging.

Ceria-stabilized meso-Al2O3: synthesis, characterization and desorption kinetics

A highly stable mesoporous ceria-doped alumina for steam gasification of biomass was synthesized using a template free method. Aluminum nitrate nonahydrate and cerium nitrate hexahydrate were used as the precursors to synthesize the ceria-doped alumina support by hydrolyzing it with ammonium carbonate. The thermogravimetric analysis indicates that the ceria-doped alumina support was stable up to 750 °C. By varying the amount of Ceria from 0.5 to 1.5 wt%, the structural and physico-chemical properties of the mesoporous support could be tuned. X-ray diffraction patterns showed that the newly prepared stabilized supports (calcined at 750 °C), exhibit γ-phase, while the textural characterization confirmed that all the catalyst supports are indeed mesoporous. The sample containing 1.0 wt% ceria on alumina has the highest post calcination (to 750 °C) surface area of 152 m2/g, pore volume of 0.43 mL/g, total acidity of 6.87 cm3/g, indicating its suitable application in biomass gasification. NH3-desorption kinetics studies revealed that 1.0 wt % Ce containing Ce/Al2O3 sample has higher activation energy for NH3 desorption than bare Al2O3, implying a moderate Ce/Al2O3 matrix interaction and that ceria incorporation will not impair active site availability of the alumina support. Finally, the high oxygen carrying capacity of ceria coupled with the synthesis method, which ensured a high dispersion of ceria in alumina matrix are responsible for the observed thermal stability. The favorable properties of these new alumina supports, can serve them as potential candidates for steam gasification of biomass among other applications, when loaded with the appropriate metal, metal oxide, or an organic functional group.

The advantage of ceria loading over V2O5/Al2O3 catalyst for vapor phase oxidative dehydrogenation of ethylbenzene to styrene using CO2 as a soft oxidant

The present work highlights the influence of ceria over vanadia/alumina for the oxidative dehydrogenation of ethylbenzene to styrene with CO2 as a soft oxidant. Various weight loadings (0, 3, 5, and 7 %) of ceria were incorporated into 10wt % V2O5/Al2O3 catalyst by wet impregnation process. Structural and textural characterizations of the catalysts were performed by means of powder X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of CO2, N2 adsorption–desorption analysis. Over 10 % V2O5/Al2O3, ethylbenzene conversion decreases from 62 to 49 % in a spam of 12 h. Ceria-incorporated catalyst (3 % CeO2/10 % V2O5/Al2O3) showed steady ethylbenzene conversion of nearly 65 % with a styrene selectivity of 96 % for a period of 12 h time. Improved catalytic activity observed on this catalyst can be attributed to the increase in the number of redox/active VOx species after incorporation of ceria. The redox properties of 3 % CeO2/10 % V2O5/Al2O3 and 10wt % V2O5/Al2O3 were examined by reaction of CO2 in pulses on to the partially reduced catalysts. The spent catalysts were characterized using XRD & TPR analysis to assess the reason for the deactivation of catalysts.

Enhanced VOC oxidation over Ce/CoMgAl mixed oxides using a reconstruction method with EDTA precursors

CoMgAl hydrotalcites were synthesized as precursors of mixed oxides in order to obtain the oxidation catalysts of toluene. Additionally, mixed oxides were promoted with the incorporation of ceria which was carried out by two methods: the hydrotalcite reconstruction method using pre-synthesized cerium chelate as a precursor [Ce-EDTA]−1; and by the traditional technique of wetness impregnation with Ce nitrate. The effect of the Ce element on the solid's physical properties and catalytic performance was investigated. The final oxides were analyzed using inductively coupled plasma-optical emission spectrometry (ICP), specific surface area, X-ray diffraction (XRD), temperature programmed reduction with H2, (H2-TPR), X-ray photoelectron spectroscopy (XPS) and catalytic tests.The Ce-CoMgAl catalyst synthesized by the reconstruction method provided a good toluene conversion. It is demonstrated that the incorporation of ceria and the activity on VOC oxidation were significantly influenced by the preparation method of the promoted catalyst, the use of EDTA providing better activity because the methodology improves the redox properties of the catalyst.

Enhanced Sulfur Tolerance of Ceria-Promoted NO x Storage Reduction (NSR) Catalysts: Sulfur Uptake, Thermal Regeneration and Reduction with H2(g)

SO x uptake, thermal regeneration and the reduction of SO x via H2(g) over ceria-promoted NSR catalysts were investigated. Sulfur poisoning and desulfation pathways of the complex BaO/Pt/CeO2/Al2O3 NSR system was investigated using a systematic approach where the functional sub-components such as Al2O3, CeO2/Al2O3, BaO/Al2O3, BaO/CeO2/Al2O3, and BaO/Pt/Al2O3 were studied in a comparative fashion. Incorporation of ceria significantly increases the S-uptake of Al2O3 and BaO/Al2O3 under both moderate and extreme S-poisoning conditions. Under moderate S-poisoning conditions, Pt sites seem to be the critical species for SO x oxidation and SO x storage, where BaO/Pt/Al2O3 and BaO/Pt/CeO2/Al2O3 catalysts reveal a comparable extent of sulfation. After extreme S-poisoning due to the deactivation of most of the Pt sites, ceria domains are the main SO x storage sites on the BaO/Pt/CeO2/Al2O3 surface. Thus, under these conditions, BaO/Pt/CeO2/Al2O3 surface stores more sulfur than that of BaO/Pt/Al2O3. BaO/Pt/CeO2/Al2O3 reveals a significantly improved thermal regeneration behavior in vacuum with respect to the conventional BaO/Pt/Al2O3 catalyst. Ceria promotion remarkably enhances the SO x reduction with H2(g).

The different NOxtrap performance on ceria and barium/ceria containing LNT catalysts below 200 °C

The low-temperature NOx storage efficiency of Ce-containing lean NOx trap catalysts was investigated using temperature programmed adsorption. The incorporation of ceria either as a NOx storage phase or as the support for barium oxides improves the NOx storage capacity from 200 °C to 350 °C. However, as temperature increases from 100 °C to 150 °C, the rate of NOx storage slows down over the catalysts containing ceria as a storage phase, while this phenomenon is less obvious if ceria is used as the support for barium oxides. By investigating the individual components of catalysts using NO-TPD, we found that the NOx release was mainly from ceria. Based on the in situ DRIFT data, we conclude that nitrite species are formed on ceria during the NOx storage at low temperatures, and the nitrite species can be activated and transformed to nitrate species upon further oxidation, accompanied by NO release; on the other hand, NO release occurs weakly on barium/ceria as the nitrites are more stable on the more basic Ba phase than on the ceria. In addition, the dispersion of barium species on ceria is higher than that on γ-Al2O3, resulting in the formation of a larger amount of basic sites. The addition of barium onto ceria not only improves the stability of ad-NOx species but also positively impacts the amounts of NOx trapped.

The degradation mitigation effect of cerium oxide in polymer electrolyte membranes in extended fuel cell durability tests

In this work, two formulations of cerium oxide nanoparticles were incorporated into perfluorosulfonic acid membrane electrode assemblies (MEAs) and their ability to improve the in-situ membrane durability was studied by subjecting them to 94 and 500 h open-circuit voltage hold accelerated durability tests. In the shorter test the open circuit voltage decay rate was reduced by half and the fluoride emission by at least one order of magnitude, though no effect on hydrogen crossover or performance on the baseline MEAs was measured. The presence of the additive increased the particle size but decreased the number of platinum catalyst particles that were deposited in the membrane. The main Pt band was found at the predicted location; however, the incorporation of ceria caused a broadening with particles reaching further into the membrane. In 500 h tests, ceria-containing MEAs demonstrated a seven-fold decrease in open-circuit voltage decay and three orders of magnitude reduction in fluoride emission rates with unchanged performance and hydrogen crossover, remaining effectively pristine whilst the baseline MEA underwent catastrophic failure.