CeO2 Nanocomposites Research Articles

Reduced graphene oxide – CeO2 nanocomposites for photocatalytic dye degradation

Over the past few decades, the widespread use of dyes has led to considerable environmental pollution, posing serious threats to human health and ecosystems. In this context, here focus on a tailored nanocomposite comprising reduced graphene oxide (rGO) and cerium oxide (CeO2) to eradicate methylene blue (MB) dye. The fabrication process involves a facile synthesis wherein CeO2 nanoparticles are anchored onto rGO sheets through co-precipitation treatment by mixing a precursor salt of cerium with graphene oxide (GO) in presence of reducing agent. The resulting nanocomposites were characterized using X-ray diffraction (XRD) analysis which confirms the crystallite size of CeO2 and rGO-CeO2 determined to be 21.61 nm and 10.74 nm respectively. Further FE-SEM analysis vividly illustrates the relatively spherical form of CeO2, which is dispersed on the rGO surface and energy dispersive X-ray spectroscopy (EDX) results provide clear evidence of the presence of carbon, cerium and oxygen in the composite. Additionally, Fourier-transform infrared spectroscopy (FTIR) confirms the composition of the rGO-CeO2 nanocomposites demonstrating the existence of various oxygen-containing groups, including O–H, C=O and Ce–O bonds. Thermogravimetric analysis (TGA) highlights that the rGO-CeO2 nanocomposites exhibits higher thermal stability with only 21.88 % weight loss up to 400 °C. Moreover, the photocatalytic activity of rGO-CeO2 nanocomposite exhibits a remarkable 94.92 % degradation of MB dye within 80 min under optimal conditions of UV light irradiation (λ = 254 nm), with a catalyst dosage of 7 mg in a 20 ppm of MB dye solution at pH 9. In contrast, pristine rGO and CeO2 achieved only 32.27 % and 38.48 % in 100 and 90 min respectively. The kinetics of photocatalysis process were meticulously studied and revealed that they followed pseudo-second order kinetic model suggesting chemisorption of MB dye onto nanocomposites prior to degradation. The stability of the nanocomposite was assessed under optimal conditions, demonstrating robust MB degradation (78 %) even up to the 4th cycle. Overall, the successful outcomes of this study show significant potential for degrading MB dye in wastewater by using the rGO-CeO2 nanocomposite.

Biomass-derived activated carbon/cerium oxide nanocomposite as adsorptive photocatalyst for effective removal of carcinogenic dye

Semiconductor-based photocatalysts offer potential solutions for carcinogenic dye-related issues in water under light irradiation. However, their efficiency is affected by the recombination of photoelectrons and holes. The present study focuses on synthesizing biomass-derived activated carbon (AC), Cerium Oxide (CeO2), and AC/CeO2 (ACO) nanocomposites for toxic dye degradation. The physicochemical properties of samples were analyzed by XRD, SEM, EDX, TEM, UV–visible, Raman, XPS, and PL analysis. The photocatalytic performance of AC, CeO2, and ACO nanocomposites was evaluated under dark and light conditions for the removal of carcinogenic Rhodamine B (RhB). ACO nanocomposites exhibited adsorptive-photocatalytic performance, displaying unique adsorption and photocatalytic degradation rates due to their synergistic combination. Remarkably, the ACO-4 composite showed lower recombination of e−/h+ pairs, thereby exhibiting superior photocatalytic activity compared to other samples. The degradation rate constant under light was 0.1815 min⁻¹ with a half-life time of 3.81 min, whereas in dark, it was 0.0665 min⁻¹ with a half-life time of 10.42 min.

Efficient one-pot green synthesis of carboxymethyl cellulose/folic acid embedded ultrafine CeO2 nanocomposite and its superior multi-drug resistant antibacterial activity and anticancer activity.

Due to the prevalence of drug-resistant bacteria and the ongoing shortage of novel antibiotics as well as the challenge of treating breast cancer, the therapeutic and clinical sectors are consistently seeking effective nanomedicines. The incorporation of metal oxide nanoparticles with biological macromolecules and an organic compound emerges as a promising strategy to enhance breast cancer treatment and antibacterial activity against drug-resistant bacteria in various biomedical applications. This study aims to synthesize a unique nanocomposite consisting of CeO2 embedded with folic acid and carboxymethyl cellulose (CFC NC) via a green precipitation method using Moringa oleifera. Various spectroscopic and microscopic analyses are utilized to decipher the physicochemical characteristics of CFC NC and active phytocompounds of Moringa oleifera. Antibacterial study against MRSA (Methicillin-resistant Staphylococcus aureus) demonstrated a higher activity (95.6%) for CFC NC compared to its counterparts. The impact is attributed to reactive oxygen species (ROS), which induces a strong photo-oxidative stress, leading to the destruction of bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CFC NC are determined as 600µg/mL and 1000µg/mL, respectively. The anticancer activity against breast cancer cell resulted in the IC50 concentration of 10.8μg/mL and 8.2μg/mL for CeO2 and CFC NC respectively.The biocompatibility test was conducted against fibroblast cells and found 85% of the cells viable, with less toxicity. Therefore, the newly synthesized CFC NC has potential applications in healthcare and industry, enhancing human health conditions.

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.

Preparation and characterisation of NH3 gas sensor based on PANI/Fe-doped CeO2 nanocomposite

PANI/Fe-doped CeO2nanocomposite was synthesised by the in-situ process. The produced powders were characterised by XRD, XPS, FT-IR, Raman, HRTEM and SEM-EDS tests. The sensors' function was based on PANI/Fe-doped CeO2nanocomposite with thin film deposited on top of interdigitated electrodes (IDT). NH3 detection with PANI/Fe-doped CeO2 nanocomposite sensor could be successfully performed even at room temperature (RT) and relative humidity of 45 %. Results demonstrated that PANI/Fe-doped CeO2 might be promising sensing materials for detecting the low NH3 concentration (ppm). In addition, the sensor is selective to the interfering gases, including CO, CO2 and NO2. This sensor displays acceptable repeatability and stability over time.

Bergera koenigii stem-derived magnetic biochar nanocomposite for enhanced photocatalytic efficiency of Ce1-xZnxO2-δ NPs under UV light for the degradation of methyl orange

The production of mesoporous, nanocrystalline, Zn-doped CeO2 nanoparticles (NPs) at various concentrations of Zn, Magnetic biochar (MBC)-Zn-doped CeO2 nanocomposites (NC), their characterizations, and photocatalytic degradation analysis are presented in this study. The synthesis of MBC-Ce0.91Zn0.09O2-δ NC is based on the carbonization of an iron oxide precursor with powdered Bergera koenigii stem (curry leaf stem). XRD and TEM results confirm polycrystalline, spherical fluorite Ce1-xZnxO2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC formations. The crystallite size varies from 4–12 nm with an increase in the doping concentration of Zn and 8.55 nm for MBC-Ce0.91Zn0.09O2-δ NC. XPS analysis displays the valence states and surface chemical composition of the as-prepared MBC-Ce0.91Zn0.09O2-δ sample. BET analysis provides the surface area (17–32 m2/g for Ce1-xZnxO2-δ NPs and 142 m2/g for MBC-Ce0.91Zn0.09O2-δ NC) and pore size (25–45 Å for Ce1-xZnxO2-δ NPs and 17.35 Å for MBC-Ce0.91Zn0.09O2-δ NC) of all the samples. All the samples possess good UV absorption in the range of 200–400 nm, and the bandgap energy of the as-prepared samples decreased from 3.088 to 2.79 eV with increased dopant concentration and on-load magnetic biochar. The oxygen deficiencies and lattice deformations of the as-prepared samples are studied using Raman, FTIR, and photoluminescence (PL) spectra. The degradation efficiency of 5 ppm Methyl Orange (MO) is analyzed using 50 mg catalytic (Ce1-xZnxO2-δ NPs, MBC-Ce0.91Zn0.09O2-δ NC) dosage by maintaining the pH of the solution as 4. After 16 min of UV irradiation, the as-synthesized Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC exhibit 91 % and 97 % decolorization and 90 % and 94 % total organic carbon (TOC) removal efficiency. Regression analysis is performed to evaluate each model's applicability to photocatalytic degradation. The regeneration experiments on Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC prove the stability of these catalysts for activating MO.

Synergistic Enhancement of Water-Splitting Performance Using MOF-Derived Ceria-Modified g-C3N4 Nanocomposites: Synthesis, Performance Evaluation, and Stability Prediction with Machine Learning.

Diminishing the charge recombination rate by improving the photoelectrochemical (PEC) performance of graphitic carbon nitride (g-C3N4) is essential for better water oxidation. In this concern, this research explores the competent approach to enhance the PEC performance of g-C3N4 nanosheets (NSs), creating their nanocomposites (NCs) with metal-organic framework (MOF)-derived porous CeO2 nanobars (NBs) along with ZnO nanorods (NRs) and TiO2 nanoparticles (NPs). The synthesis involved preparing CeO2 NBs and g-C3N4 NSs through the calcination of respective precursors, while the sol-gel method is employed for ZnO NRs and TiO2 NPs. Following the subsequent analysis of the physicochemical properties of the materials, the binder-free brush-coating method is deployed to fabricate NC-based photoanodes, followed by an evaluation of the PEC performance through various electrochemical techniques. Remarkably, the binary g-C3N4/CeO2 NCs with 20 wt % CeO2 NBs (gC20 NCs) exhibited a significantly enhanced current density of 0.460 mA/cm2 at 1.23 V vs reversible hydrogen electrode, which is 2.3 times greater than that of bare g-C3N4 NSs (0.195 mA/cm2). Further improvements are observed with ternary gC20/TiO2 (gCT50) and gC20/ZnO (gCZ50) NCs, achieving current densities of 1.810 and 1.440 mA/cm2, respectively. These enhanced current densities are attributed to increased donor densities, reduced charge transfer resistances, and efficient charge transport within the NCs. In addition, higher surface areas with beneficial instinctive defects are perceived for gCT50 and gCZ50 NCs, as revealed by Brunauer-Emmett-Teller and electron spin resonance analysis. Finally, the stability of gCZ50 and gCT50 NC-based photoanodes is predicted and forecasted with the help of the recurrent neural network-based long short-term memory technique. Overall, this study demonstrates the efficacy of organic-inorganic hybrids for efficient photoanodes, facilitating advancements in water-splitting studies.

One-pot synthesis of g-C3N4/N-doped CeO2 nanocomposites and their potential visible light-driven photocatalytic degradation of methylene blue dye.

In the pursuit of efficient photocatalytic materials for environmental applications, a new series of g-C3N4/N-doped CeO2 nanocomposites (g-C3N4/N-CeO2 NCs) was synthesized using a straightforward dispersion method. These nanocomposites were systematically characterized to understand their structural, optical, and chemical properties. The photocatalytic performance of g-C3N4/N-CeO2 NCs was evaluated by investigating their ability to degrade methylene blue (MB) dye, a model organic pollutant. The results demonstrate that the integration of g-C3N4 with N-doped CeO2 NCs reduces the optical energy gap compared to pristine N-doped CeO2, leading to enhanced photocatalytic efficiency. It is benefited from the existence of g-C3N4/N-CeO2 NCs not only in promoting the charge separation and inhibits the fast charge recombination but also in improving photocatalytic oxidation performance. Hence, this study highlights the potential of g-C3N4/N-CeO2 NCs as promising candidates for various photocatalytic applications, contributing to the advancement of sustainable environmental remediation technologies.

Investigation of biological efficacy assessment of cobalt-doped cerium oxide nanocomposites against pathogenic bacteria, fungi, and lung cancer cells

This paper presents the fabrication of cobalt doped-cerium oxide nanocomposites (Co/CeO2 NCs) by solid combustion method. Synthesized cobalt doped CeO2 nanocomposites and pure CeO2 were confirmed by UV–Visible spectrophotometer, Fourier transform infrared spectrometer (FTIR), X-ray diffraction study (XRD), BET analysis and transmission electron microscope coupled with energy dispersive spectroscopy (TEM-EDS). The bandgap energies of CeO2, 0.25, 0.50 and 0.75%Co/CeO2 NCs were 3.02, 2.98, 2.81 and 2.80 eV, respectively. The 50 % inhibitory concentration (IC50) values of CeO2, 0.25, 0.50, and 0.75 % of Co-doped CeO2 were 57.02, 38.65, 35.33 and 39.87 μg/mL, respectively. The oxidation state of Cobalt and Cerium was confirmed by X-ray photoelectron spectrum. The Co/CeO2 NCs exhibited a zone of inhibition against bacteria and fungi. Thus, Co/CeO2 NCs can be used as a biomaterial for controlling pathogenic bacteria, fungi and lung cancer cell lines.

Facile synthesis of nickel doped ZnO and CeO2 nanocomposite for efficient photocatalytic dye degradation, catalytic reduction and antimicrobial studies

The current research work reports on binary Nickel oxide-Zinc oxide (NiO-ZnO) and Nickel oxide-Cerium oxide (NiO-CeO2) nanocomposites synthesis by facile single step in-situ thermal decomposition method and its applications. The structural and morphological studies were examined using various characterization techniques like IR, UV-DRS, XRD and SEM with EDAX studies. The IR bands at 545-533 cm−1 corresponds to M-O stretching vibration. The XRD studies confirms the structural pattern of NiO-ZnO and NiO-CeO2 nanocomposites. SEM with EDAX results reveal the structure, composition and purity of synthesized nanocomposites. The nanocomposites were employed as photocatalyst for degradation of methylene blue and methyl orange dyes and as a catalyst toward 4-nitrophenol reduction. Antibacterial studies against E. coli (Gram-negative) and S. aureus (Gram-positive) bacterial pathogens were carried out using the nanocomposites. The outcomes show 97% efficiency in forty minutes for catalysis and 120 min for dye degradation and a better zone of inhibition in antibacterial studies for NiO-ZnO nanocomposite. The comparative result for both the nanocomposites discloses that the photocatalytic degradation, catalytic and antimicrobial efficiency of NiO-ZnO nanocomposite is more efficient than NiO-CeO2 nanocomposite. The results reveal the outstanding catalytic and dye degradation and antibacterial activity of NiO-ZnO than NiO-CeO2.

Exploring the biomedical potential of chitosan‐ceria nanocomposites: synthesis and characterizations

The objective of this study was to synthesize and evaluate the biological effectiveness of cerium oxide (CeO2) against various bacterial and fungal strains. The chitosan‐CeO2nanocomposite was comprehensively characterized. The Fourier transform infrared (FTIR) spectra displayed a combination of bands that provided evidence for the existence of a composite complex between the chitosan (CS) structure and the Ce–O bands originating from CeO2nanoparticles. SEM measurements showed uniform dispersion across the whole CS surface, and the morphological changes were clearly observed as the CeO2nanoparticle content was increased. In contrast, CS‐CeO2demonstrates enhanced antibacterial efficacy against both Gram‐positive and Gram‐negative pathogens. The MTT method was utilized to assess the cytotoxicity of the examined CS‐CeO2, with the aim of evaluating the cell viability of various cancer cell lines under varying ultraviolet (UV) exposures. The enhanced penetration of CS and CeO2nanocomposites into cancer cells during their anticancer activity, even in the absence of UV light, led to an increased rate of cell death. The administration of greater dosages of CS and its CeO2nanocomposites led to an increased generation of reactive oxygen species (ROS), which was observed to be associated with an enhancement in the efficacy of anticancer activity. The impact was additionally amplified through exposure to UV radiation. The nanocomposite thin films demonstrated much higher antioxidant activity against the DPPH radical as compared to ordinary vitamin C. The aforementioned observation was derived from an evaluation of the antioxidant properties of the subject utilizing the DPPH free radical scavenging technique.

Effect of Copper Particle Size on the Surface Structure and Catalytic Activity of Cu–CeO2 Nanocomposites Prepared by Mechanochemical Synthesis in the Preferential CO Oxidation in a H2-Rich Stream (CO-PROX)

An effect of Cu powder dispersion and morphology on the surface structure and the physical–chemical and catalytic properties of Cu–CeO2 catalysts prepared by mechanochemical synthesis was studied in the preferential CO oxidation in a H2-rich stream (CO-PROX). Two catalysts, produced by 30 min ball-milling from CeO2 and 8 mass% of copper powders and with particle sizes of several tens (dendrite-like Cu) and 50–200 nm (spherical Cu obtained with levitation-jet method), respectively, were characterized by X-ray diffraction and electron microscopy methods, a temperature-programmed reduction with CO and H2, and with Fourier-transform infrared spectroscopy. The catalyst synthesized from the “large-scale” dendrite-like Cu powder, whose surface consisted of CuxO (Cu+) agglomerates located directly on the surface of facetted CeO2 crystals with a CeO2(111) and CeO2(100) crystal planes exposition, was approximately two times less active at 120–160 °C than the catalyst synthesized from the fine Cu powder, whose surface consisted of CuxO (Cu2+) clusters of 4–6 nm in size located on the steps of facetted CeO2 nanocrystals. Although a large part of CO2 reacted with a ceria surface to give carbonate-like species, no blockage of CO-activating centers was observed due to the surface architecture. The surface structure formed by the use of highly dispersed Cu powder is found to be a key factor responsible for the catalytic activity.

Antibacterial and sunlight-driven photocatalytic activity of graphene oxide conjugated CeO2 nanoparticles

This work focuses on the structural, morphological, optical, photocatalytic, antibacterial properties of pure CeO2 nanoparticles (NPs) and graphene oxide (GO) based CeO2 nanocomposites (GO-1/CeO2, GO-5/CeO2, GO-10/CeO2, GO-15/CeO2), synthesized using the sol–gel auto-combustion and subsequent sonication method, respectively. The single-phase cubic structure of CeO2 NPs was confirmed by Rietveld refined XRD, HRTEM, FTIR and Raman spectroscopy. The average crystallite size was calculated using Debye Scherrer formula and found to increase from 20 to 25 nm for CeO2 to GO-15/CeO2 samples, respectively. The related functional groups were observed from Fourier transform infrared (FTIR) spectroscopy, consistent with the outcomes of Raman spectroscopy. The optical band gap of each sample was calculated by using a Tauc plot, which was observed to decrease from 2.8 to 1.68 eV. The valence state of Ce (Ce3+ and Ce4+) was verified using X-ray photoelectron spectroscopy (XPS) for CeO2 and GO-10/CeO2. The poisonous methylene blue (MB) dye was used to evaluate the photocatalytic activity of each sample in direct sunlight. The GO-15/CeO2 nanocomposite showed the highest photocatalytic activity with rate constant (0.01633 min–1), and it degraded the MB dye molecules by 100% within 120 min. The high photocatalytic activity of this material for degrading MB dye establishes it as an outstanding candidate for wastewater treatment. Further, these nanocomposites also demonstrated excellent antimicrobial activity against Pseudomonas aeruginosa PAO1.

Scope of magnesium ceria nanocomposites for mandibular reconstruction: Degradation and biomechanical evaluation using a 3-dimensional finite element analysis approach

Magnesium/Ceria nanocomposites (Mg/xCeO2 NCs (x = 0.5 %, 1 % and 1.5 %)) prepared by using powder metallurgy and microwave sintering method are assessed for their corrosion rate for a period of 28 days. As per the immersion tests results, the addition of ceria nanoparticles to pure Mg, brought about a noteworthy improvement to corrosion resistance. A corrosion rate of approximately 0.84 mm/year for Mg/0.5CeO2 and 0.99 mm/year for Mg/1.0CeO2 nanocomposites were observed. Another aspect of the study involves employing the simulation method i.e. finite element analysis (FEA) to compare the stress distribution in magnesium-ceria nanocomposite based screws and circular bars especially for Mg/0.5CeO2 and Mg/1.0CeO2. Further, the simulation also gives a perception of the impact of masticatory forces, the biting force and shear stress exerted on the Mg/0.5CeO2 and Mg/1.0CeO2 based screws. The simulations results show that the screws showed an acceptable level of stresses for a biting force up to 300 N. The circular bar as well kept its stresses at acceptable levels for the same load of 300N. The shear stress results indicated that a biting force up to 602 N can be safely absorbed by Mg/0.5CeO2 screw. The comprehensive approach allows for a better understanding of the corrosion behavior, stress distribution, and mechanical properties of the Mg/CeO2 nanocomposites, enabling the development of effective temporary implants for craniofacial trauma fixation that can withstand normal physiological forces during mastication. The study reported in this paper aims to target Mg/xCeO2 NCs for temporary implants for craniofacial trauma fixation.

Comparison of Shallow (−20 °C) and Deep Cryogenic Treatment (−196 °C) to Enhance the Properties of a Mg/2wt.%CeO2 Nanocomposite

Magnesium and its composites have been used in various applications owing to their high specific strength properties and low density. However, the application is limited to room-temperature conditions owing to the lack of research available on the ability of magnesium alloys to perform in sub-zero conditions. The present study attempted, for the first time, the effects of two cryogenic temperatures (−20 °C/253 K and −196 °C/77 K) on the physical, thermal, and mechanical properties of a Mg/2wt.%CeO2 nanocomposite. The materials were synthesized using the disintegrated melt deposition method followed by hot extrusion. The results revealed that the shallow cryogenically treated (refrigerated at −20 °C) samples display a reduction in porosity, lower ignition resistance, similar microhardness, compressive yield, and ultimate strength and failure strain when compared to deep cryogenically treated samples in liquid nitrogen at −196 °C. Although deep cryogenically treated samples showed an overall edge, the extent of the increase in properties may not be justified, as samples exposed at −20 °C display very similar mechanical properties, thus reducing the overall cost of the cryogenic process. The results were compared with the data available in the open literature, and the mechanisms behind the improvement of the properties were evaluated.

Synergistic design and fabrication of g-C3N4 decorated Ni-doped CeO2 nanocomposite: A highly efficient photo and electrocatalyst for enhanced energy storage and environmental remediation

Environmental pollution and energy storage are two of the most important problems in the modern world. There is an urgent need for the development of materials with multifunctional properties to successfully address these issues. In this study, we investigate the potential applications of the g-C3N4/Ni-doped CeO2 binary composite, specifically focusing on supercapacitor and photocatalytic performance. To synthesize the pristine CeO2, Ni-doped CeO2 and g-C3N4/CeO2 hybrid samples, we employed an ultrasonic-assisted hydrothermal method and employed various characterization techniques to gain insights into their morphological, structural, optical and compositional characteristics. The synthesized materials are studied for their electrochemical behavior as supercapacitor electrodes using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Additionally, their photocatalytic performance is evaluated under sunlight with Methylene Blue (MB) dye. The hybrid composite electrode demonstrated a peak specific capacitance (Cs) of 269 F/g at a current density of 1 A/g. Moreover, the device maintained an 85.22 % retention rate even after undergoing 5000 consecutive charge/discharge cycles. Moreover, following 60 min of exposure to natural light irradiation, the photocatalytic degradation rates for MB were observed to be 52.5 %, 69.3 %, and 82.3 % for pristine CeO2, Ni-CeO2, and g-C3N4/Ni-CeO2, respectively. The hybrid composite material, g-C3N4/Ni-CeO2, outperforms both CeO2 and Ni-doped CeO2 nanoparticles in terms of enhanced photocatalytic efficiency and improved electrochemical performance, making it highly promising for applications in wastewater treatment and supercapacitors.

Toxicity of Titanium Dioxide-Cerium Oxide Nanocomposites to Zebrafish Embryos: A Preliminary Evaluation.

The widespread use of metal nanoparticles in different fields has raised many doubts regarding their possible toxicity to living organisms and the accumulation and discharge of metals in fish species. Among these nanoparticles, titanium dioxide (TiO2) and cerium oxide (CeO2) nanoparticles have mainly been employed in photocatalysis and water depuration. The aim of this research was to evaluate the potential toxic effects, after a co-exposure of TiO2-3%CeO2 nanoparticles, on zebrafish development, using an acute toxicity test. Increasing concentrations of TiO2-3%CeO2 nanoparticles were used (0.1-1-10-20 mg/L). The heartbeat rate was assessed using DanioscopeTM software (version 1.2) (Noldus, Leesburg, VA, USA), and the responses to two biomarkers of exposure (Heat shock proteins-70 and Metallothioneins) were evaluated through immunofluorescence. Our results showed that the co-exposure to TiO2-3%CeO2 nanoparticles did not affect the embryos' development compared to the control group; a significant difference (p < 0.05) at 48 hpf heartbeat for the 1, 10, and 20 mg/L groups was found compared to the unexposed group. A statistically significant response (p < 0.05) to Heat shock proteins-70 (Hsp70) was shown for the 0.1 and 1 mg/L groups, while no positivity was observed in all the exposed groups for Metallothioneins (MTs). These results suggest that TiO2-3%CeO2 nanocomposites do not induce developmental toxicity; instead, when considered separately, TiO2 and CeO2 NPs are harmful to zebrafish embryos, as previously shown.

Impedance spectroscopy analysis on reduced graphene oxide and CeO2 nanocomposites coated on screen-printed alumina substrate for highly selective H2S gas detection at room temperature

Impedance spectroscopic-based gas sensing analysis is a highly sensitive technique. Impedance and its fitted RC circuits provide us with fundamental information about grain boundary, grain bulk, and the interface between sensing film and electrode contact. In this work, an n-CeO2/rGO composite-based gas sensing film with high selectivity, sensitivity, stability and moisture resistance potency for the detection of H2S was developed on screen-printed alumina substrate using a drop casting process, and the H2S gas sensing performance was evaluated using electrochemical impedance spectroscopy (EIS) at various temperatures. The n-CeO2/rGO-3 composite produced stable and rapid responses towards H2S with a response of 97.41 % for 50 ppm of H2S gas at the optimum temperature of room temperature (27 °C). The LOD and LOQ were calculated and found to be ∼0.9 and ∼2.9 ppm for n-CeO2 and n-CeO2/rGO-3 composites, respectively. The superior selectivity with interfering gases such as NH3, H2, SO2 and CO, response and recovery time (∼9s and ∼12s), long-time stability and gas sensing mechanism were investigated. This impedance-based gas sensor development opens up the path for the fabrication of n-CeO2/rGO composite-based H2S gas sensors for future applications.

“Adsorptive removal of Congo Red dye from its aqueous solution by Ag–Cu–CeO2 nanocomposites: Adsorption kinetics, isotherms, and thermodynamics”

Eliminating synthetic dyes and organic contaminants from water is crucial for safeguarding human health and preserving the environment. In this study, we explored the effectiveness of Ag–Cu–CeO2 nanocomposites as adsorbents to remove Congo Red dye from water. Three compositions of Ag–Cu–CeO2 nanocomposites (10:20:70, 15:15:70, and 20:10:70) have been synthesized by the aqueous coprecipitation method. A comprehensive analysis was performed by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, BET surface area determination, Thermogravimetric analysis, Scanning electron microscopy, and TEM. The synthesized nanocomposites have a dimension of 5 ± 1 nm and a high surface area (51.832–78.361 m2g-1).Among these, the nanocomposite with composition 15:15:70 showed the highest adsorption capacity of 4.71 mg/g adsorption (96.83 % removal) from the 0.8 × 10−4 M (55.6 mg/l) Congo Red solution at pH values of 2 at 20 °C with contact time of 3h. The adsorption data is best fitted in the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The negative values of enthalpy variation (−27.57, −26.43, and −16.73 kJ/mol) demonstrated that the adsorption was spontaneous and exothermic. The cycling run showed a mere 12 % deactivation after five cycles of use thus indicating that Ag–Cu–CeO2 nanocomposites hold great potential as effective and eco-friendly adsorbents to remove Congo Red from water.

CeO2 nanorods decorated In2O3 nanoparticles for enhanced low temperature detection of hydrogen

Hydrogen (H2) detection sensors based on pure CeO2 nanorods (NRs) and In2O3-loaded CeO2 NRs with different In2O3 contents (5 wt%, 10 wt%, and 15 wt%) were investigated. The crystal phase evolution, morphology features, and response characteristics of the In2O3-loaded CeO2 NRs were analyzed in detail using characteristic techniques. Gas sensing results showed that the In2O3-loaded CeO2 gas sensors exhibited superior H2 sensing performances compared with pure CeO2 NRs under low operating temperature (100 °C). Notably, the gas sensors based on the 10 wt% In2O3-loaded CeO2 nanocomposite showed the most refined performance, with response values of 2.79 and 2.43 times higher than those of the pure CeO2 NRs sensors for 1000 ppm and 4000 ppm H2, respectively. The response values exhibited a linear relationship with the detection concentration. Moreover, the In2O3-loaded CeO2 gas sensor demonstrated enhanced H2 selectivity, good recyclability, and long-term stability. Finally, the improved gas sensing mechanism of the In2O3-loaded CeO2 gas sensor for H2 was also proposed.