CeO2 Composites Research Articles

Initial Stages of Water Absorption on CeO2 Surfaces at Very Low Temperatures for Understanding Anti-Icing Coatings

Abstract Anti-icing coatings are intended to prevent ice formation on surfaces, minimising the risk of surface-related damage and also reducing ice-related hazards in society. We demonstrate the usefulness of X-ray photoelectron spectroscopy (XPS) as a tool for investigating the anti-icing properties of surfaces simultaneously with their chemical composition by looking at the initial stages of water absorption on the surface of CeO2 coatings. CeO2 coatings are robust, hydrophobic, and transmit light, thus they are suitable for a range of applications. In this work, CeO2 coatings were grown by sputter deposition and transferred to an ultra-high vacuum chamber where they were cooled to ≈100 K and exposed to a H2O atmosphere at 1×10-8 mbar. XPS measurements were performed before and after the exposure to H2O, in-situ and at cryogenic temperatures. The chemical composition of CeO2 did not change significantly during the experiment. Additionally, XPS revealed that little to no ice formed on the surface of CeO2 after the H2O exposure at ≈100 K. In contrast, ice was observed all over the sample holder on which the CeO2 was mounted. These findings suggest CeO2 is a promising candidate for future anti-icing coatings and that XPS is a useful technique to investigate the anti-icing properties of surfaces.

Effect of Morphology and Concentration of CeO2 Nanoceria on the Thermal Stability of Polyvinyl Alcohol Films

Objective: To determine the thermal stability of polyvinyl alcohol films under different concentrations of CeO2 nanoceria. Method: Cerium Oxide doped polyvinyl alcohol (PVA) nano-composites were synthesized by the traditional solution casting method for various concentrations of nano CeO2 by solution combustion method. The thermal properties of prepared PVA-2.5 wt% CeO2, PVA-7.5 wt% CeO2 , PVA-12.5 wt% CeO2, and PVA-25 wt% CeO2 composite films were elucidated by using techniques such as Differential Scanning Calorimetry, Thermogravimetry analysis and Differential Thermal analysis. Findings: The glass transition temperature of the pure PVA is found to be 114°C, whereas it varies between 110°C-120°C for composite films. The melting temperature of the composite films is the same as that of pure PVA except in the case of 7.5wt% CeO2 and 25wt% CeO2 composites. The reduced melting point of these composites elicits a decrease in crystallinity. A 12.5 wt % and 25 wt% CeO2-PVA nano-composite films exhibit an increase in the final degradation temperature, a high specific heat capacity, low mass loss, and a larger residual weight, indicating their potential applicability in thermal coating and thermal sensing applications. Polyvinyl alcohol (PVA) films are being used routinely as a dielectric layer for electrical applications due to the good physiochemical and dialectic properties of the material. An incorporation of CeO2 nanoceria improves not only the thermal but also the mechanical properties of PVA and extends its application for electrical and optical operation. Here in the present study, different concentrations of CeO2 were incorporated with the PVA and analysed for the thermal properties. The study showed that 12.5 wt % and 25 wt% CeO2-PVA nano-composite enhanced PVA film thermal stability. Keywords: PVA-CeO2 Nanocomposites; Differential Scanning Calorimetry; Thermogravimetry Analysis and Differential Thermal Analysis; Physical properties and thermal properties

Wet-chemical preparation and physicochemical characterization of nanostructured Zn-Bi2O3/CeO2 composite: A visible-light-driven catalyst for the annihilation of pharmaceutical pollutant

A modified co-precipitation technique assisted with cetyltrimethylammonium bromide (CTAB) surfactant was used to synthesize a nanostructured and zinc-doped mixed metal oxide (Zn-Bi2O3/CeO2) composite. Using X-ray diffraction (XRD), the synthesized nanocomposite was studied in terms of its crystal structure, grain size, percentage crystallinity, and percentage porosity. Energy dispersive X-ray elemental analysis (EDX) was used to ascertain the chemical composition, SEM to confirm the creation of nanostructure material, and Fourier transform infrared spectroscopy (FTIR) to extract the existing functional groups. Investigation of light harvesting properties (UV/Vis) and thermogravimetric analysis (TGA) reveals that the doped composite exhibits a band gap driven by visible light and remarkable thermal stability at high temperatures. The pH value at which a material's net charge is zero, known as pHpzc, is 7.93 for the doped mixed metal oxide composite. The Zn-Bi2O3/CeO2 nanocomposite effectively eliminates 98.4 percent of the quinolone antibiotic (levofloxacin) via a mechanism that integrates sorption and photocatalytic degradation induced by visible light. To determine the optimal circumstances for the efficient operation of a photocatalyst, we experimented with different time intervals, beginning drug concentrations, catalyst dosages, operating temperatures, and pH levels. Reusability tests and post-activity FTIR analysis were used to investigate the long-term usability and structural stability of the newly developed doped composite photocatalyst. The scavenging tests revealed a potential photocatalytic mechanism to explain the annihilation of the levofloxacin drug on the synthesized catalyst. The physicochemical and photocatalytic evaluations recommend that the assembled integrated material has excellent potential for mineralizing medicinal products in pharmaceutical wastes.

Synergistic effects of CQDs and oxygen vacancies on CeO2 photocatalyst for efficient photocatalytic nitrogen fixation

The combination of carbon quantum dots (CQDs) with oxygen vacancies (OVs) provides a promising approach to achieving efficient photocatalytic nitrogen fixation. It was by a hydrothermal method that CQDs-modified CeO2 composites (CQDs/CeO2) were synthesized. The synergistic effects of CQDs and OVs on CeO2 photocatalyst enhanced interfacial electron transfer capabilities, thus the photocatalytic nitrogen fixation was significantly enhanced. CQDs/CeO2 exhibited the most superior efficiency in photocatalytic nitrogen fixation, reaching 826 μmol·g−1·h−1, when the addition of CQDs was 200 µL. It was the introduction of CQDs that effectively regulated the concentration of OVs. OVs captured the electrons, thus promoting electron transfer. This enhancement not only improved the electron-hole separation efficiency in CQDs/CeO2 but also greatly promoted the adsorption and activation of N2 by OVs. This work offered a novel strategy for designing efficient photocatalysts for nitrogen fixation.

Interface reconstruction of MXene-Ti3C2 doped CeO2 nanorods for remarked photocatalytic ammonia synthesis

Prospective photocatalytic ammonia synthesis process has received more attentions but quite challenging with the low visible light utilization and weak N2 molecule absorption ability around the photocatalysts. Herein, interface reconstruction of MXene-Ti3C2/CeO2 composites with high-concentration active sites through the carbon-doped process are presented firstly, and obvious transition zones with the three-phase reaction interface are formed in the as-prepared catalysts. The optimal co-doped sample demonstrates an excellent photo response in the visible light region, the strongest chemisorption activity and the most active sites. Moreover, much more in-situ extra oxygen defects are also produced under light irradiation. It is expected that the double decorated catalyst shows a remarked ammonia production rate of above 0.76 mmol gcal−1·h−1 under visible-light illumination and a higher apparent quantum efficiency of 1.08 % at 420 nm, which is one of the most completive properties for the photocatalytic N2 fixation at present.

Spectroscopic Investigations of Complex Electronic Interactions by Elemental Doping and Material Compositing of Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

AbstractDoping and compositing are two universal design strategies used to engineer the electronic state of a material and mitigate its disadvantages. These two strategies are extensively applied to design efficient electrocatalysts for water splitting. Using cobalt oxide (CoO) as a model catalyst, it is proven that the oxygen evolution reaction (OER) performance can be progressively improved, first by Fe‐doping to form Fe‐CoO solid solution, and further by the addition of CeO2 to produce a Fe‐CoO/CeO2 composite. X‐ray absorption spectroscopy (XAS) reveals that distinct electronic interactions are induced by the processes of doping and compositing. Fe‐doping of CoO can break down the structural symmetry, changing the electronic structure of both Co and O species at the surface and decreasing the flat‐band potential (Vfb). In comparison, subsequent compositing of Fe‐CoO with CeO2 induces negligible electronic changes in the Fe‐CoO (as seen in ex situ characterizations), but significantly modifies the oxidative transformations of both Co and Fe under OER conditions. The spectroscopic investigations reveal that Fe‐doping and CeO2 compositing play different roles in modifying the electronic properties of CoO in its pristine state and during OER catalysis, in return, providing useful guidance for the design of more efficient electrocatalysts using these two strategies.

Sulfated CeO2-TiO2 as H2 evolution photocatalyst: Synergic effects of heterojunction and sulfation on catalyst performance

SO42−/CeO2/TiO2 composite oxides are successfully fabricated via sol-gel method and impregnation process for photocatalytic H2 production. The characterization results from XRD, FTIR and TEM revealed that the heterojunctions were formed by the formation of Ti-O-Ce bond across the SO42−/CeO2/TiO2 interface, which was contributed significantly to separation of photo-generated carriers. Py-FTIR spectra and XPS results indicated that Lewis acid and Brønsted acid sites were formed over the surface of SO42−/CeO2/TiO2 composite, which was owing to SO42− coordinated to the metal on the sample surface. The induced Lewis acid sites could enhance the separation of photogenerated carriers, and Brønsted acid sites could provide protons for photocatalytic H2 production. In addition, the Lewis acidity could facilitate the shift of conduction band minimum to a more negative value, which improves the photocatalytic H2 production capacity of SO42−/CeO2/TiO2. The results of photocatalytic H2 production revealed that SO42−/CeO2/TiO2 composite exhibits superior photocatalytic activity compared to bare CeO2, TiO2 and CeO2-TiO2 composite. Notably, it achieves the average H2 yield rate of 6295.2 μmol·g−1 h−1 over a period of 5 h. Combine the results of spectra analysis and photocatalytic activity H2 evolution, it can be concluded that the synergetic effects of heterojunction structure of CeO2/TiO2 composite and acid impregnation promoted the photocatalyst activity.

Self-nitrogen-doped carbon spheres assisted CeO2 composites as a bifunctional adsorbent/photocatalyst for CO2 photoreduction

It is rather essential to increase CO2 adsorption and improve separation efficiency of photoinduced carriers by solar-driven CO2 reduction. Herein, we proposed a facile approach to synthesize millimeter-sized polyacrylonitrile-based carbon spheres (PANACSs) as a bifunctional adsorbent and self-nitrogen-doped source under a mild condition, and then embeds the highly active CeO2 to construct a CeO2@PANACSs composite with strong adsorption capacity and high reduction activity. The involved XRD, XPS, SEM, N2 adsorption/desorption, CO2 adsorption, UV–vis DRS, EIS, PL and In situ FTIR spectra were characterized. Results suggested that the obtained PANACSs can act as a catalyst to drive the reduction of CO2 into CO under visible light irradiation. CeO2@PANACSs showed the highest performance of photocatalytic reduction of CO2 for 10 h (210.65 μmol·g−1), and the yield of CO evolution is approximately 1.83 times and 17.42 times higher than that of pristine CeO2 and PANACSs, respectively. We found that the existence of nitrogen-containing functional groups further promoted the adsorption and activation of CO2. Among them, pyridinic nitrogen and pyrrolic nitrogen can be used as adsorption and activation sites to accelerate the separation and transfer of e--h+. Furthermore, Ce4+ on the surface of CeO2 acts as an electron capture agent, which captures the electrons that are not transferred in time and reduces itself to Ce3+, and then the formed Ce3+ reduces the adsorbed CO2 to CO. Finally, the possible mechanism is proposed to depict the photocatalytic CO2 reduction over the CeO2@PANACSs. Our finding provides a noteworthy promising strategy to construct bifunctional composite photocatalysts for achieving the high-efficient CO2 adsorption and photoreduction to CO.

Study on the negative oxygen ion release behavior and mechanism of tourmaline composites

Negative air ions are becoming increasingly popular as they purify the air by adsorbing dust and hazardous substances, which are beneficial to people's health. The ternary composites of tourmaline and monazite with graphene, germanium, cerium oxide, lanthanum oxide, and titanium oxide were prepared by the ball milling process, and the release of negative oxygen ions was investigated. The enhanced mechanism of tourmaline is analyzed systematically by hysteresis loop with monazite and other substances. The results indicate that monazite relies on its thorium element to generate radioactive energy to excite negative ions. It was discovered that the T/10%M/15%CeO2 composites exhibited the optimum negative ion release performance of 6580 ions/cm3, which is approximately 5–6 times compared to tourmaline. The results of conductivity and hysteresis loop tests demonstrate that tourmaline stimulates negative oxygen ions due to its spontaneous polarization effect and the formation of a polarized electric field. The spontaneous polarization effect of tourmaline is positively correlated with the release amount of negative oxygen ions.

Thermodynamic analysis on CSP integrated cerium oxide (CeO2 − CeO1.72/1.83) water splitting cycle for hydrogen production

Solar thermochemical CeO2-based H2O splitting cycle was thermodynamically analyzed to ascertain the optimal thermal reduction (TH) and re-oxidation (TL) temperatures and evaluate the solar-to-fuel conversion efficiency (ηsolar−to−fuel) of the cycle. The equilibrium composition of CeO2, CeO1.72,CeO1.83 and O2 exhibited that the thermal reduction initiated at 1400 K thereby attaining 100 % TR at 2734 K. The observed variations in Gibbs free energy (ΔG) correspond to the feasibility of the re-oxidation step of CeO1.83 and CeO1.72 at 1050 K and 1200 K respectively. It was reported that the absorption efficiency of solar reactor (ηabs−solar−reactor−WS) decreases from 95.6 % to 37 %, as the TH increases from 1400 K to 2734 K. The results show that ηsolar−to−fuel reached the maximum value of 7.45 % for CeO1.72 and 7.69 % for CeO1.83 at 61.72 % TR of CeO2 without heat recuperation. Further, the ηsolar−to−fuel attained the maximum value of 14.92 % and 13.54 % for CeO1.83 and CeO1.72, respectively at the %TR of CeO2 of 80 % with 50 % heat recuperation. The solar-to-fuel conversion efficiency (ηsolar−to−fuel) further can be increased with the optimization of oxygen partial pressure (PO2) and molar flow rate of reduction regents (Ar or N2).

Enhanced anti-aging behaviors in cubic phase CeO2 induced BaSnO3 thermosensitive ceramics

The anti-aging ability is an important index to measure the temperature measurement application of thermosensitive materials. Herein, the BaSnO3 + xCeO2 (x = 0 %, 2 %, 4 %, 7 %) ceramics were synthesized via mixing BaSnO3 with CeO2. By combining with CeO2, some Ce4+ replaces Sn4+ to improve the phase structure stability, which improves the high-temperature stability of the thermosensitive ceramic, reducing the aging coefficient from 50 % to 2.5 %. Meanwhile, the resistivity decreases with the increase of CeO2 composition, which can be attributed to the increase of Ce3+ content, resulting in the increase of the number of small polaron. With the increase of x content, thematerial constant B500/850, activation energy Ea and resistivity ρ500 of the ceramic decrease. The B values and Ea values of the thermistors are in the range of 12341–17155 K and 1.06–1.48 eV, respectively. These results indicate that BaSnO3 + xCeO2 composites are potential candidates in high temperature NTC thermistor devices.

Effect of friction stir processing on mechanical, in vitro degradation, and biocompatibility behaviour of stir casted Mg-Zn-rare earth oxide composites for biodegradable implant applications

The current work takes the benefit of utilizing a composite approach by reinforcing Mg with Zn, Cerium oxide - a rare earth and bone-friendly ceramic, and bioactive hydroxyapatite to develop magnesium-based MMCs for high structural integrity and low degradation inside the human body via stir casting technique in a protective Ar-SF6 environment. The friction stir processing (FSP) technique was employed to tailor the properties of as-cast Mg composites, resulting in further grain refinement and better dispersion of reinforced materials. Phase and microstructure analysis were analyzed via XRD, FESEM, and optical microscopy. During tensile tests, as-cast Mg-5Zn-1HA-1.5CeO2 improved 68.6% in yield strength and 16.3% in ultimate tensile strength. After FSP, the same composite resulted in an overall improvement of 114.6% in yield strength and 31.9% in ultimate strength compared to as-cast pure Mg. Dispersion of inert bioceramics within the Mg matrix results in higher polarization resistance as per Electrochemical impedance spectroscopy (EIS). At the same time, a remarkable 81.6% reduction in H2 emission and an 84.4% decrement in corrosion rate were found during the immersion study for Mg-5Zn-1HA-1.5CeO2 composites. All Mg-based composites exhibited no cytotoxicity as cell viability evaluated via MTT assay was found to be greater than 80% for 50% and 25% extract concentrations. The composite’s hemolysis rate was below 5%, indicating acceptable hemocompatibility. This work provides insight into developing rare earth oxide-incorporated Mg composites with better mechanical capabilities and degradation resistance while avoiding the long-term cytotoxicity of rare-earth materials.

Effect of CeO2–Ni addition on the behavior of AZ91- A356 based composite fabricated by friction solid state technique

This study aims to investigate the behavior of AZ91- A356 alloy after the addition of CeO2 and Ni using the friction stir processing (FSP) technique. The Macrostructure of AZ91- A356/2 % Ni/5 % CeO2 showed a crack-free and defect-free composite. The microstructure image showed fair distribution for AZ91- A356/2 % Ni/5 % CeO2 composite. The interfacial layer analysis aimed to determine the formation and characteristics of the layer between the processed alloy and the reinforcement. A strong interfacial layer between A356-AZ91, CeO2, and Ni was found for AZ91- A356/2 % Ni/5 % CeO2 composite. The addition of 5 % CeO2 and 2% Ni showed a 44.78% improvement in tensile strength and a 38.84% improvement in hardness. The number of grains was found to be about 2521.38 per square inch at 500 magnifications for AZ91- A356/2 % Ni/5 % CeO2 processed composite with FSP. The formations of Al, Mg, NiAl3, CeO2, and Ni phases were observed in XRD. The wear rate of AZ91- A356 alloy decreased by about 68.85% after the addition of the 2% Ni- 5% CeO2 particles. The results of this study will contribute to a better understanding of the processing-structure-properties relationship in the A356-AZ91 alloy and guide the development of improved dissimilar materials and processing techniques.

Rare Earth Oxides-Containing Internal Reference Material of Purified Monazite from Bangka Island

Monazite mineral contains a sufficient composition of rare earth elements which are currently required widely in modern industries. Reference materials are needed to validate the measurement results, including the rare earth elements analysis. This study presents the processing of purified monazite from the PT Timah Metallurgical Unit in Muntok to become low-cost and rare earth oxides-containing internal reference material. Eight X-ray fluorescence measurements of four splits of the monazite were done for precision test and to establish its information values. The high CeO2 and LaO2 composition (>10%) implies the economic worth of the studied sample. Based on the acceptance criteria of RSDexperimental <10%, RSDexperimental ?66%xCVHorwitz, and Horrat <2, the concentration of fourteen analytes is acceptable to be set as information values. The studied monazite content resembles the other purified one of Myanmar. Its much lower phosphate composition signifies that the sample is more precious than refined monazites from Iran and Australia.

Functional nanosheet fillers with fast Li+ conduction for advanced all-solid-state lithium battery

Polymer electrolyte-based solid-state lithium metal batteries can accommodate high energy density and address safety issues, while polymer electrolytes suffer from low lithium ion migration and weak mechanical strength. Hence, as an exceptionally facile and practical strategy, it is of great significance to search for functional fillers to lift the performance of current polymer electrolytes and explore their role in ion transport. Nanosheet materials with a positive charge field, such as VO,NCECN (CeO2 and g-C3N4 composites containing oxygen and nitrogen defects), are outstanding candidates. Combining the calculated and experimental results, we reveal the unique nanosheets structure could achieve the maximum area of contact with PEO, so that the surface of the filler is exposed to more coordination sites to promote the transport of Li+, and improve the ion conductivity (1.08×10−5 S cm−1 at 25°C). As a result, a lithium battery consisting of composite solid electrolyte (CSE) still has a capacity of 135 mAh g−1 after 200 cycles at a current density of 0.3 C when matched with a commercial NCM811 electrode. These findings highlight that functional fillers improve the electrochemical properties of polymers and provide a feasible design solution for high-performance solid electrolytes.

Unveiling the Future of Insulator Coatings: Unmatched Corrosion Resistance and Self-Healing Properties of PFPE Lubricating Oil-Infused Hydrophobized CeO2 Surfaces

Corrosion accounts for 52% of the recorded breakdown of insulators utilized in transmission lines, which may interfere with the reliability of power utilities. The CeO2 conversion coating, CeO2-ethylene propylene diene monomer, EPDM composite coating, and Perfluoropolyether PFPE lubricating oil-infused hydrophobized CeO2 composite surfaces were developed on the insulator surface to address these challenges. The properties of these three kinds of structures are compared based on the persistence of coating over insulators installed in a highly contaminated environment. PFPE lubricating oil-infused hydrophobized CeO2 composite surfaces show excellent performance over other approaches. A lubricating oil-infused hydrophobized CeO2 composite of thickness 35.4 µm exhibits contact angles 60°, 85°, and 160°, and contact angle hysteresis of 12°, 10°, and 4°, respectively, after accelerated thermal aging. The proposed approach presents self-healing and corrosion resistance (corrosion rate 0.3 × 10−3 mm/Y, Icorr 1.2 × 10−7), post-accelerated thermal aging. The research outcome is expected to pave the way for incredibly robust insulator coatings.

Effect of High Current Pulsed Electron Beam (HCPEB) on the Organization and Wear Resistance of CeO2-Modified Al-20SiC Composites.

This paper investigates the joint effect of high current pulsed electron beam (HCPEB) and denaturant CeO2 on improving the microstructure and properties of Al-20SiC composites prepared by powder metallurgy. Grazing Incidence X-ray Diffraction (GIXRD) results indicate the selective orientation of aluminum grains, with Al(111) crystal faces showing selective orientation after HCPEB treatment. Casting defects of powder metallurgy were eliminated by the addition of CeO2. Scanning electron microscopy (SEM) results reveal a more uniform distribution of hard points on the surface of HCPEB-treated Al-20SiC-0.3CeO2 composites. Microhardness and wear resistance of the Al-20SiC-0.3CeO2 composites were better than those of the Al matrix without CeO2 addition at the same number of pulses. Sliding friction tests indicate that the improvement of wear resistance is attributed to the uniform dispersion of hard points and the improvement of microstructure on the surface of the matrix after HCPEB irradiation. Overall, this study demonstrates the potential of HCPEB and CeO2 to enhance the performance of Al-20SiC composites.

Spherical CeO2 synthesized by molten-salt with unique fast variable valence properties for lithium-ion battery anode

As an important rare earth oxide, fluorite CeO2 is widely used in lithium ion batteries because it can quickly and directly change the oxidation state of cerium from Ce3+ to Ce4+. In this work, the ball milling method and the molten salt approach were both used to successfully produce amorphous carbon-coated CeO2 composite. The CeO2@C composite has excellent rate characteristics, high reversibility, and cycling stability. In contrast to the pure CeO2 electrode, the reversible capacity of CeO2@C remains at 264.8 mAh/g after 100 cycles at 100 mA g−1, with a capacity retention rate of 79.3%. The CeO2@C specific capacity is returned to 257.2 mAh/g, accounting for 89% of the initial capacity, after large current fluctuations and returning to the initial current density.

Designing photoelectrode architecture modified with mesoporous MCM-41/CeO2 composites as specific scattering layers for dye-sensitized solar cells

Depositing light scattering film on top of the photoactive layer of dye-sensitized solar cells (DSSCs) is one method to boost the device efficiency. Therefore, mesoporous MCM-41 and CeO2 were prepared and coated on TiO2 photoactive layer in both their pure and composite (1–4 wt% CeO2:MCM-41) forms by doctor blade technique. XRD, FESEM, EDS, TEM, BET, FTIR, DRS, and PL analyses were employed to characterize all compounds. Additionally, the power conversion efficiency (PCE), dye adsorption capacity, and charge transfer parameters of various DSSCs were measured. The data taken from J-V plots indicated that the highest conversion efficiency belonged to 2 wt% CeO2:MCM-41 when was used as the scattering layer which could boost the efficiency up to 7.42% with fill factor (FF), open-circuit voltage (Voc) and short-circuit current density (Jsc), respectively, equal to 0.48, 0.752 V, 20.55 mA.cm−2, confirming 78.8% greater efficiency than the bare TiO2 containing DSSC (PCE = 4.15%, FF = 0.39, Voc = 0.736 V, Jsc = 14.45 mA.cm−2). In fact, once 2 wt% CeO2:MCM-41 with large particles was applied, according to Mie's theory, prolonged the light path through incident light scattering, which resulted in more light harvesting by photoanode material, further dye molecules excitation, and improvement in the current density. Also, because of the insulating nature of silica material in 2 wt% CeO2:MCM-41 layer, it reduced the charge recombination process and accelerated the transfer of electrons from the TiO2 photoanode to the Pt counter electrode via the external circuit. Besides, high porosity and huge surface area (757.34 m2/g) of 2 wt% CeO2:MCM-41 promoted dye molecules to be adsorbed additionally which generated extra photoelectrons.

Influence of Y Doping on Catalytic Activity of CeO2, MnOx, and CeMnOx Catalysts for Selective Catalytic Reduction of NO by NH3

Novel yttrium-doped CeO2, MnOx, and CeMnOx composites are investigated as catalysts for low-temperature NH3-SCR. The study involves the preparation of unmodified oxide supports using a citrate method followed by modification with Y (2 wt.%) using two approaches, including the one-pot citrate method and incipient wetness impregnation of undoped oxides. The NH3-SCR reaction is studied in a fixed-bed quartz reactor to test the ability of the prepared catalysts in NO reduction. The gas reaction mixture consists of 800 ppm NO, 800 ppm NH3, 10 vol.% O2, and He as a balance gas at a WHSV of 25,000 mL g−1 h−1. The results indicate that undoped CeMnOx mixed oxide exhibits significantly higher deNOx performance compared with undoped and Y-doped MnOx and CeO2 catalysts. Indeed, yttrium presence in CeMnOx promotes the competitive NH3-SCO reaction, reducing the amount of NH3 available for NO reduction and lowering the catalyst activity. Furthermore, the physical-chemical properties of the prepared catalysts are studied using nitrogen adsorption/desorption, XRD, Raman spectroscopy, temperature-programmed reduction with hydrogen, and temperature-programmed desorption of ammonia. This study presents a promising approach to enhancing the performance of NH3-SCR catalysts at low temperatures that can have significant implications for reducing NO emissions.