Incorporation Of Ce Research Articles

Efficient catalytic oxidation of xylose to formic acid with the oxygen vacancies of CeO2 promoted the vanadium catalysts anchored on biochar

The catalytic oxidation of carbohydrates for the preparation of formic acid (FA) is an prominent route for high-value utilisation of biomass. Reforming xylose, a biomass derivative, into FA with high efficiency is essential for the advancement of non-homogeneous V-type catalysts. Here, we present the self-assembly of V and Ce onto a cellulose pulp for the synthesis of oxygen vacancy (Ov)-rich non-homogeneous-bimetallic catalysts (5Ce-VOx/BC-600). Under the optimised conditions, 71.46 % FA was obtained, which far exceeded the catalytic performance of the single-metal catalyst. Furthermore, the 5Ce-VOx/BC-600 catalyst showed excellent stability and reusability. Kinetic studies revealed that glyceric and glycolic acids served as the pivotal intermediates, undergoing subsequent deacidification and oxidation processes to yield FA and CO2. The analysis of the catalytic mechanism indicated that the incorporation of Ce enhanced the quantity of acidic sites and the concentration of Ov in the 5Ce-VOx/BC-600 catalyst, which promoted substrate adsorption and O2 activation. Meanwhile, the catalyst showed high lattice oxygen (OL) mobility and assisted the redox cycle of V5+/V4+ to oxidise xylose to FA. Significantly, the synergistic effect of Ce, V species and Ov enhances the OL mobility of the catalysts, thus promoting the efficient oxidation of xylose. The catalytic system was further extended to the oxidation of other biomass derivatives to FA, demonstrating excellent catalytic performance.

Ti/Cr regulated and strategic Ce doped V-Ti-Cr-Mn-Fe high-entropy alloys with extraordinary reversible hydrogen storage properties at ambient temperature

High-entropy alloys (HEAs) are garnering widespread interest due to their exceptional hydrogen storage capabilities at ambient temperatures. Herein, a series of HEAs composed of V-Ti-Cr-Mn-Fe with varying Ti/Cr ratios has been synthesized via arc melting to serve as carrier materials for room-temperature hydrogen storage. Thanks to the composition of a large amount of body centered cubic (BCC) phase V32TixCr58-xMn5Fe5 exhibits excellent hydrogen storage performance, and the hydrogen absorption capacity of these HEAs escalates while the desorption capacity initially rises followed by a decline with an increase in the Ti/Cr ratio. Notably, the HEA with a Ti/Cr ratio of 1.0, namely V32Ti29Cr29Mn5Fe5, demonstrates exceptional performance by absorbing 3.55 wt% H2 within 60 min and rapidly releasing 2.16 wt% H2 within 5 min at 303 K. Further enhancement is achieved with the strategic doping of Ce in the V32Ti29Cr29Mn5Fe5, which leads to the removal of the Ti-rich phase and the incorporation of CeO2, significantly improves the activation performance, allowing the Ce-doped HEA to reach saturation in the 3rd hydrogen absorption cycle. Consequently, the hydrogen ab-/desorption capacities at ambient temperature are further augmented to 3.73 wt% and 2.26 wt%, respectively, and the enthalpies of hydrogen ab-/desorption are significantly reduced to −25.0 and 23.4 kJ/mol H2, marking a new benchmark for V-based HEAs. Dramatically, DFT calculations suggestes that the incorporation of Ce diminishes the structure energy of BCC phase structure for V32Ti29Cr29Mn5Fe4Ce1 as well as elongates the average distance of M−H from 1.955 Å to 1.969 Å, which corroborate the experimental results, offering profound insights into the underlying mechanisms of hydrogen storage within BCC-phase HEAs at ambient temperature.

Improved transparency and charge matching of electrochromic devices with Ce-doped NiO counter electrode

The quest for cost-effective and efficient electrochromic electrodes, featuring high color contrast and rapid response times, has sparked increasing interest in research of metal oxides for electrochromic applications. In this study, nickel oxide thin films with various cerium dopant concentrations are synthesized, with the optimized doping concentration identified as 1 at%. X-ray diffraction analysis confirmed that the dopant successfully reduces crystal size and alters the preferred orientation to (111). The 1 % Ce:NiO thin film exhibits enhanced electrochromic performance, with a transmittance modulation increase of 27.4 % at 633 nm, a 27.1 % rise in coloration efficiency and faster response time (tb=9.64 s and tc=6.76 s) compare to the undoped NiO. Importantly, the charge density of 1 % Ce:NiO thin film increases from 4.86 to 8.14 mC cm−2, representing a 67.5 % improvement, which becomes a better charge matching with WO3 in electrochromic devices. The incorporation of Ce into the NiO thin films not only leads to increased transmittance in the bleached state and optical modulation in the electrochromic devices but also contributes to a rise in the optical band gap of the NiO thin films and improved charge balance matching. These results underscore the positive impact of cerium doping on microstructure and electrochromic performance, indicating a promising future for electrochromic devices.

DBD plasma assisted synthesis of Ce-MIL-88B(Fe) with electron-rich CUSs and mixed-valent bimetallic sites for enhanced photo-Fenton performance

Iron-based metal-organic frameworks (Fe-MOFs) are regarded as a kind of prospective catalysts for photo-Fenton process. However, high cost, rate-limiting Fe(III)/Fe(II) circulation and limited metal sites greatly restricted the application of Fe-MOFs in photo-Fenton system. Ce-MIL-88B(Fe) was synthesized with mixed-valent bimetallic sites and tunable coordinated unsaturated metal sites (CUSs) using dielectric barrier discharge (DBD) plasma with waste PET. The incorporation of Ce altered the structure and the electron aggregation, as well as induced structural defects. Ce substitution in Fe-MOFs induced the regulation of the ratio of Fe ions and formation of electron-rich CUSs, which were beneficial for the rapid adsorption and activation of H2O2, thus enhancing the photo-Fenton performance. The effect of reaction conditions on TC degradation was investigated by response surface methodology (RSM) combined with Box-Behnken design (BBD). This study demonstrates a new perspective on the construction of bimetallic MOFs for the photo-Fenton system.

Importing Atomic Rare‐Earth Sites to Activate Lattice Oxygen of Spinel Oxides for Electrocatalytic Oxygen Evolution

Spinel oxides have emerged as highly active catalysts for the oxygen evolution reaction (OER). However, due to covalency competition, the OER process on spinel oxides often follows an arduous adsorbate evolution mechanism (AEM) pathway. Herein, we propose a novel rare‐earth sites substitution strategy to tune the lattice oxygen redox of spinel oxides and bypass the AEM scaling relationship limitation. Taking NiCo2O4 as a model, the incorporation of Ce into the octahedral site induces the formation of Ce‐O‐M (M: Ni, Co) bridge, which triggers charge redistribution in NiCo2O4. The developed Ce‐NiCo2O4 exhibits remarkable OER activity with a low overpotential, satisfactory electrochemical stability, and good practicability in anion‐exchange membrane water electrolyzer. Theoretical analyses reveal that OER on Ce‐NiCo2O4 surface follows a more favorable lattice oxygen mechanism (LOM) pathway and non‐concerted proton‐electron transfers compared to pure NiCo2O4, as further verified by pH‐dependent behavior and in situ Raman analysis. 18O‐labeled electrochemical mass spectrometry directly demonstrates that oxygen originates from the lattice oxygen of Ce‐NiCo2O4 during OER. It is discovered that electron delocalization of Ce 4f states triggers charge redistribution in NiCo2O4 through the Ce‐O‐M bridge, favoring antibonding state occupation of Ni‐O bonding in [Ce‐O‐Ni] site, thereby activating lattice oxygen redox of NiCo2O4 in OER.

Importing Atomic Rare-Earth Sites to Activate Lattice Oxygen of Spinel Oxides for Electrocatalytic Oxygen Evolution.

Spinel oxides have emerged as highly active catalysts for the oxygen evolution reaction (OER). However, due to covalency competition, the OER process on spinel oxides often follows an arduous adsorbate evolution mechanism (AEM) pathway. Herein, we propose a novel rare-earth sites substitution strategy to tune the lattice oxygen redox of spinel oxides and bypass the AEM scaling relationship limitation. Taking NiCo2O4 as a model, the incorporation of Ce into the octahedral site induces the formation of Ce-O-M (M: Ni, Co) bridge, which triggers charge redistribution in NiCo2O4. The developed Ce-NiCo2O4 exhibits remarkable OER activity with a low overpotential, satisfactory electrochemical stability, and good practicability in anion-exchange membrane water electrolyzer. Theoretical analyses reveal that OER on Ce-NiCo2O4 surface follows a more favorable lattice oxygen mechanism (LOM) pathway and non-concerted proton-electron transfers compared to pure NiCo2O4, as further verified by pH-dependent behavior and in situ Raman analysis.18O-labeled electrochemical mass spectrometry directly demonstrates that oxygen originates from the lattice oxygen of Ce-NiCo2O4 during OER. It is discovered that electron delocalization of Ce 4f states triggers charge redistribution in NiCo2O4 through the Ce-O-M bridge, favoring antibonding state occupation of Ni-O bonding in [Ce-O-Ni] site, thereby activating lattice oxygen redox of NiCo2O4 in OER.

Synergistic impact of lanthanum and cerium co-doping ZnO for improved photocatalytic rhodamine B degradation efficiency under UV light

In this study, the influence of different La and Ce co-doping amounts on the structural, morphological, optical, and photodegradation properties of ZnO nanostructures was evaluated. Zn1-2xLaxCexO nanoparticles (NPs) were prepared using sol-gel auto-ignition process, where x = 0.00 (pure ZnO), 0.01 (LC1), 0.03 (LC3), and 0.05 (LC5). The X-ray diffraction (XRD) and Raman results revealed that the prepared ZnO NPs crystallize in the hexagonal wurtzite structure. The size of crystallites is affected by the increment of La and Ce and it decreased from 24.29 nm to 10.40 nm with the increase in the concentration of La and Ce. Transmission electron microscopy (TEM) showed that the samples exhibit an irregular distribution of NPs with a dominant spherical shape morphology. The simultaneous incorporation of La and Ce in ZnO NPs led to a slight variation in the absorption edge and a slight shift in the values of the band gap energy from 3.20 to 3.24 eV. Furthermore, a reduction in the recombination rate of photogenerated charge carriers and the creation of fewer additional defects upon the appropriate insertion of Ce and La ions are highlighted by the analysis of photoluminescence spectra, Nyquist plots, and transient photocurrent measurements. The photocatalytic activity of samples was evaluated against rhodamine B organic dye under UV light irradiation. The analysis showed that LC1 sample exhibited superior photocatalytic performance with 99.1% degradation efficiency and a degradation rate constant of 0.0762 min-1. This enhancement has been ascribed to the surface defects and the optimized crystallite size achieved, which help to generate reactive entities such as •OH and O2•− in addition to the great role of holes (h+) and impede the recombination of charge carriers e-/h+.

Role of cerium dopant in tuning the semiconductor-to-metal transition properties of magnesium zinc ferrite nanomaterials

In this research work, Magnesium zinc ferrite (CexMgZn1-xFe2O4) nanomaterials have been synthesized with various cerium concentrations (x = 0, 0.05, 0.1, 0.15) using the coprecipitation method. With no deformation as per structural analysis, cerium ions are doped in the spinel lattice of MgZnFe2O4 nanomaterials. The undoped MgZnFe2O4 with initial flake-like morphology is changed to cube-like shapes upon Ce (x = 0.15) addition. The DC resistivity exhibits a varying pattern in both ferromagnetic and paramagnetic regions as temperature increases. Furthermore, the samples with x = 0.15 exhibit a high resistivity on the order of 1.09∗1010 Ω cm, and an activation energy of 0.909 eV. The dielectric properties, such as dielectric constant, dielectric losses, and impedance, exhibit a progressive drop as the frequency increases from 1 MHz to 2 MHz. Furthermore, dielectric parameters reach their lowest value in the dopant x = 0.1. The highest Q values for x = 0.05 and 0.15 indicate that the mentioned materials are most suitable for use in high-frequency devices, likewise multi-layer chip inductors and resonant circuits. Growth inhibition of two types of bacterial extracts (E.Coli and S. aureus) has been studied. Results revealed MgZnFe2O4 enhanced growth inhibition against S. aureus bacteria with increasing Ce concentration, however, inhibition of E. Coli is hampered (50 % at maximum) by Ce incorporation into ferrite lattice.

A New Approach to Single‐Step Fabrication of TiOx‐CeOx Nanoparticles

Mixed metal oxide (MMO) nanoparticles (NPs) are hybrids consisting of two or more nanoscale metal oxides. Advantages of MMO NPs over single metal oxides include improved catalytic activity, enhanced electrical and magnetic properties, and increased thermal stability due to the synergy of the different oxide components. This study presents a novel fabrication route for TiO2‐CeO2 NPs enriched with oxygen vacancies using a Haberland‐type gas aggregation cluster source. The NPs, deposited from different segmented Ti/Ce targets under varying O2 addition, were examined with respect to final composition, morphology, and Ti, Ce surface oxidation states. Particle formation mechanisms are proposed for the observed morphologies. Additionally, available O2 during deposition and its impact on the formation of defective sites were investigated. Defective sites in TiO2‐CeO2 NPs were analyzed using transfer to X‐ray photoelectron spectroscopy and transmission electron microscopy without contact to ambient oxygen. The incorporation of Ce to the target exhibits synergistic effects on the synthesis process. Segmented Ti/Ce targets enable the deposition of a broad range of mixed oxide NPs with diverse compositions and morphologies at considerably enhanced deposition rates, which is vital for practical applications. The presented fabrication approach is expected to be applicable for a broad variety of MMO NPs.

White afterglow achieved in Eu2+, Ce3+, Dy3+co-doped LiSr4(BO3)3 phosphor

In prior study by our team, orange-yellow afterglow was observed in Eu2+ and Dy3+ co-doped LiSr4(BO3 )3 phosphor due to the emission from Eu2+ center. In this study, further incorporation of Ce3+into the phosphor lead to the observation of white afterglow due to the mixed result of blue light from Ce3+ and orange-yellow light from Eu2+ centers. Upon ultraviolet excitation, the phosphor displays a spectrum characterized from blue emission of Ce3+ at 462nm and orange-yellow emission of Eu2+ at 632nm. Fine-tuning the concentration of Ce3+ enabled the realization of white luminescence in LiSr4(BO3)3: Eu2+, Ce3+ and Dy3+phosphor with chromaticity coordinates of (0.3979, 0.2939). The photoluminescence intensities of the samples could be modulated by incorporating varying amounts of Ce3+ ions, with a critical quenching concentration identified with 0.16 Ce3+. White afterglow is also observed after the removal of the light illumination due to the existence of suitable electron traps with optimal trap depth created by the co-doped Dy3+. The underlying mechanism proposes that the white afterglow is generated by the mixed lights of blue and orange-yellow that are created by the recombination of heat-released electrons from the trap centers with pre-existing holes in the Ce and Eu emission sites.

Effect of Ce-Doping on the Structural, Morphological, and Electrochemical Features of Co3O4 Nanoparticles Synthesized by Solution Combustion Method for Battery-Type Supercapacitors

This study investigates the potential of cerium (Ce) doping to improve the performance of cobalt oxide (Co₃O₄) nanoparticles as battery-type supercapacitor electrodes. Pure Co₃O₄ nanoparticles were synthesized via a solution combustion method and then doped with 2.5% (Ce-Co3O4) and 5% Ce (CeO2-Co3O4). Comprehensive characterization, including X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM), was used to analyze the impact of Ce doping on the material properties. XRD analysis confirmed the successful incorporation of Ce into the Co₃O₄ structure, with distinct CeO2 phases forming at higher doping levels. Ce doping resulted in decreased crystallite size and peak intensity, indicating reduced crystallinity and increased defect concentration. Raman spectroscopy corroborated these findings, showing a redshift that suggests weakened metal-oxygen bonds and smaller grain sizes due to Ce³⁺ incorporation. FESEM images demonstrated that Ce doping effectively reduced nanoparticle agglomeration, with 2.5% doping leading to smaller particles and 5% doping promoting a 2D flake-like morphology with increased porosity. Nitrogen adsorption-desorption measurements revealed a significant increase in surface area and pore volume for CeO2-Co₃O₄, facilitating improved electrolyte diffusion and reduced resistance, thereby enhancing electrochemical performance. Evaluation of the electrochemical properties of undoped and Ce-doped Co₃O₄ materials revealed a battery-like response in a three-electrode configuration. Notably, the CeO2-Co3O4 exhibited a superior specific capacity of 603.3 C g-1 at a current density of 1 A g-1, significantly exceeding the values of 368.5 C g-1 and 127.1 C g-1 achieved by Ce-Co3O4 and undoped Co3O4, respectively. Furthermore, the CeO2-doped Co3O4 demonstrated exceptional cyclic stability, retaining 87% of its initial capacity after undergoing 5000 charge-discharge cycles at a high current density of 10 A g-1. These results suggest that Ce doping is a promising strategy for optimizing Co₃O₄-based battery-type electrode materials, potentially leading to the development of high-performance and cost-effective energy storage systems.

Insights into the Acidic Site in Manganese Oxide in Terms of the Sulfur and Water Tolerance of Low-Temperature NH3 Selective Catalytic Reduction.

A critical constraint impeding the utilization of Mn-based oxide catalysts in NH3 selective catalytic reduction (NH3-SCR) is their inadequate resistance to water and sulfur. This vulnerability primarily arises from the propensity of SO2 to bind to the acidic site in manganese oxide, resulting in the formation of metal sulfate and leading to the irreversible deactivation of the catalyst. Therefore, gaining a comprehensive understanding of the detrimental impact of SO2 on the acidic sites and elucidating the underlying mechanism of this toxicity are of paramount importance for the effective application of Mn-based catalysts in NH3-SCR. Herein, we strategically modulate the acidity of the manganese oxide catalyst surface through the incorporation of Ce and Nb. Comprehensive analyses, including thermogravimetry, NH3 temperature-programmed desorption, in situ diffused reflectance infrared Fourier transform spectroscopy, and density functional theory calculations, reveal that SO2 exhibits a propensity for adsorption at strongly acidic sites. This mechanistic understanding underscores the pivotal role of surface acidity in governing the sulfur resistance of manganese oxide.

Ce doped UiO-66(Hf) electrolyte for all-solid-state lithium metal batteries

Solid electrolytes have garnered significant attention as promising candidates for all-solid-state batteries due to their excellent safety, and cycling stability. However, the development of solid electrolytes faces challenges in achieving high ionic conductivity and low interfacial impedance. In this study, we prepared a Ce doped UiO-66(Hf)-base electrolyte using a solvothermal method. The resulting electrolyte exhibited remarkable properties, including high Li-ion conductivity (3.72 × 10−3 S cm−1), a high lithium ion transfer number (tLi+ = 0.66), and stability during stripping electroplating. These impressive results can be attributed to that the shorter length of the Ce-O bond in UiO-66(Hf) compared to the Hf-O bond, which enhances the transformation of Li+ ions. The incorporation of Ce as a dopant into UiO-66(Hf) in solid electrolytes holds great promise for future applications in solid-state batteries.

Luminescence properties and energy transfer of Ce3+, Tb3+ codoped Ba2GaB4O9Cl Phosphor

In this paper, a series of Ba2GaB4O9Cl:Ce3+,Tb3+ phosphors were synthesized by the conventional high-temperature solid-state reaction. The incorporation of Ce3+ ions as sensitizers significantly enhances the absorption and luminescence intensity of Tb3+ ions in the Ba2GaB4O9Cl phosphor. The energy transfer from Ce3+ to Tb3+ occurs through the electric quadrupole-quadrupole interaction, with an energy transfer efficiency of 48 %. The internal quantum efficiency of Ba2GaB4O9Cl:Ce3+,Tb3+ phosphor is 39.95 % upon 316 nm excitation. At 423 K, the emission intensity of Ba2GaB4O9Cl:Ce3+,Tb3+ can keep 53.28 % of its initial value at room temperature. All these results indicate that the Ba2GaB4O9Cl:Ce3+,Tb3+ phosphor has potential application for white LED.

Molecular dynamics simulation study of the effect of Ce4+ incorporation at Zr site on the threshold displacement energy in Y4Zr3O12 material

ABSTRACT This study utilizes classical molecular dynamics (MD) simulations to examine the structure and the impact of cerium (Ce4+) incorporation, serving as a surrogate for plutonium (Pu), at the zirconium (Zr4+) site on the threshold displacement energy (Ed) for each atom within the δ-phase Y4Zr3O12 material along 100 different directions. The minimum Ed values obtained for Y, Zr, and O in Y4Zr3O12 are 50 eV, 60 eV, and 25 eV, respectively. Notably, the Y cation is more prone to displacement than the Zr cations, while oxygen anions are even more easily displaced than cations, requiring less energy for displacement. Furthermore, the incorporation of Ce4+ at the Zr4+ site in the Y4Zr3-3xCe3xO12 (0 ≤ x ≤ 0.5) system reduces both the minimum and average Ed values for Zr atoms. The presence of Ce also decreases the minimum Ed for Y at x = 0.5 and for OI at x = 0.125, while increasing the minimum Ed for OII at x = 0.25. These findings suggest that the incorporation of Ce can influence the radiation resistance of the Y4Zr3O12 material, thereby offering insights into potential strategies for enhancing its performance under radiation conditions.

Improved conversion, selectivity, and stability during CO2 methanation by the incorporation of Ce in Ni, Co, and Fe-hydrotalcite-derived catalysts

In this work, Ni-based mixed metal oxide (MMOs) materials were synthesized by coprecipitation, and then ceria (CeO2) was incorporated. The obtained structures were characterized by XRD, TEM, BET, H2-TPR, and CO2-TPD techniques. The synthesized materials were evaluated in the CO2 methanation process (250–400 °C range). Firstly, the effects of space velocity and Ni loading on the catalyst were tested, and 36000 h−1 and 5 % of Ni were found to be suitable conditions for CO2 conversion. The addition of Co or Fe to the Ni-based MMO was then assessed. Co improved the catalytic activity, meanwhile, the Fe addition did not have an enhancing effect. Afterward, the role of CeO2 as support on Ni-, NiFe- and NiCo-based MMOs was evaluated, evidencing that selectivity and space-time yields were enhanced in the materials by the CeO2 presence. Furthermore, due to the characteristics of CeO2, the MMO containing nickel, cobalt, and ceria was more stable, showing ∼85% conversion of CO2 after 1400 min of continuous use.

Visible light-responsive Ce-doped ZnO ceramic nanostructures as effective photocatalysts for removal of persistent organic pollutants from contaminated waters

Cerium-doped zinc oxide (ZnO) ceramic nanostructures were conceived and prepared by means of electrospinning-calcination method. Morphological analysis based on scanning electron microscopy (SEM) disclosed a transition from spherical to rod-shaped features in ZnO ceramic nanostructures upon cerium (Ce) doping amount. Powder X-ray diffraction (XRD) indicated that the unit cell parameters remained unchanged for doped ZnO, while a new diffraction peak at 2θ = 28.57° occurred above 0.5% Ce, corresponding to cubic CeO2. The results are further supported by X-ray Photoelectron Spectroscopy (XPS) investigations, which clearly confirmed the occurrence of Ce4+ ions upon the increase of Ce incorporation during the synthesis. Photocatalytic screening assays for methylene blue (MB) degradation using a visible light source, demonstrated superior performance for the doped material with 0.1% Ce content, yielding the highest pseudo-first-order rate constant (k = 4.795 × 10−2 min−1). Additionally, the best catalyst ZnO:Ce (0.1%), showed rate constants of 1.018 × 10−2 min−1 and 3.675 × 10−2 min−1 for photodegradation of metronidazole (MNZ) and ciprofloxacin (CIP), respectively, under the established optimal conditions. The catalyst stability was confirmed through multiple reuse cycles. The present study points out the effective Ce-doped ZnO nanostructures for versatile photocatalytic applications.

Enhancing the stability of NiFe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation. Nevertheless, the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry. Herein, we present our recent discovery that the incorporation of Ce into NiFe layered double hydroxide nanosheet array on Ni foam (Ce-NiFe LDH/NF) emerges as a robust electrocatalyst for seawater oxidation. During the seawater oxidation process, CeO2 is generated, effectively repelling Cl− and inhibiting the formation of ClO−, resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater. The prepared Ce-NiFe LDH/NF requires only overpotential of 390 mV to achieve the current density of 1 A cm−2, while maintaining long-term stability for 500 h, outperforming the performance of NiFe LDH/NF (430 mV, 150 h) by a significant margin. This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on NiFe LDH in seawater electrolysis for oxygen evolution.

Ce Single-Atom Incorporation Enhances the Oxygen Evolution Reaction of Co3O4 in Acid.

Oxygen evolution reaction (OER) plays an important role in energy conversion processes such as water electrolysis and metal-air batteries. At present, finding a high-performance and low-cost catalyst for the OER in acidic media remains a great challenge. It is therefore important to develop efficient, robust, and inexpensive electrocatalysts by replacing noble metal-based catalysts with transition-metal electrocatalysts. Herein, we propose a facile method for incorporating Ce-metal single atoms into Co3O4 nanosheets to boost their OER activity and stability. Owing to the enhanced charge transfer and improved electronic structure resulting from Ce incorporation, the obtained Ce single-atom-doped Co3O4 nanosheet exhibits greatly enhanced OER performance. It achieves a 10 mA cm-2 current density under a low overpotential of 348 mV in a 0.5 M H2SO4 solution with excellent stability, outperforming the state-of-the-art non-noble electrocatalysts recently reported in acid.

Selective catalytic reduction of NOX with CH4 over In/SSZ-13 zeolites: The enhancement of high-temperature catalytic activity by Ce modification

The selective catalytic reduction of nitrogen oxides by methane (CH4/NOX-SCR) is a potential technique for the abatement of the NOX emissions from lean-burn GDI engines, due to the excellent thermal stability of CH4. This work focuses on the promotion of In/SSZ-13 catalysts by Ce modification for the CH4/NOX-SCR performance at high temperatures. A series of In/SSZ-13 and Ce-In/SSZ-13 catalysts were prepared using the wetness impregnation method. The effects of Ce modification on the catalytic performance were analysed in detail using the scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectrum and temperature-programmed desorption/reduction techniques. The results show that the Ce modification significantly enhances the high-temperature activity of the In/SSZ-13 catalysts for the NOX-SCR reaction, especially for the 5 wt% Ce-15 wt% In/SSZ-13 sample which has more than 75% NOX conversion at 390–700 °C. In addition, the Ce modification enhances the water vapor tolerance of the catalyst sample. The Ce modification increases not only the concentration of surface chemisorption oxygen species, but also the relative amount of InO+ species which serve as the main active sites for CH4 activation. Furthermore, the incorporation of Ce into In/SSZ-13 greatly promotes NOX adsorption on the catalyst surface. Most importantly, the Ce modification makes In species well-dispersed on the catalyst surface and thus suppresses the formation of bulk In2O3 species which are more active for the CH4 non-selective oxidation. The combination of all these effects results in the Ce-In/SSZ-13 samples with the superior catalytic activity.