Oxygen Vacancy Concentration Research Articles

Homogeneously Co/Ce co-doped amorphous MnOx microspheres with abundant oxygen vacancy for catalytic combustion of propane

Developing simple and effective strategies to construct rich oxygen vacancies is of great importance for enhancing the catalytic efficiency of heterogeneous catalysts. This study prepared Ce and Co-doped manganese oxide catalysts with microsphere morphology by a simple and facile solvent-thermal reaction strategy, which were further applied for the catalytic combustion of chemically stable light alkane such as propane. The results of systematic characterizations verified that the incorporation of Ce and Co into MnOx generates more structural defects with abundant oxygen vacancies. The Mn3(Co2Ce1)1 catalyst, which was obtained by Co, Ce co-doping, possessed the highest content of oxygen vacancies as well as strengthened physic-chemical features such as larger specific surface, more surface-active species, better redox capacity, enhanced oxygen mobility and acidity. As a result, this sample displayed superior low-temperature catalytic activity, achieving 90 % conversion of propane at 263 °C under high space velocity (120,000 mL·gcat-1·h−1), which was 87 °C lower than that of pure manganese oxide. Moreover, in-situ DRIFTS was also employed to reveal the possible pathways of propane degradation over the Mn3(Co2Ce1)1 catalyst. Meanwhile, clear improvements reflected in thermal stability and resistance to water were also realized by modifying Co and Ce, showing great potential for practical industrial applications.

Tin oxide nanoparticles anchored on ordered mesoporous carbon for efficient acetone sensing

Rationally designed combinations of semiconductor metal oxides (SMO) and carbon materials can lead to the development of sensing materials with excellent gas performance. Herein, SnO2 nanoparticles (NPs) decorated on ordered mesoporous carbon (CMK-3) nanorods were synthetized by solvothermal and high-temperature calcination methods. Various characterization and gas sensing tests indicated that the resulting one-dimensional (1D) self-assembled SnO2@CMK-3 composite had a large specific surface area (88.02 m2/g) and excellent gas sensing performance. Specifically, at optimal working temperature, the as-prepared SnO2@CMK-3 sensor had a high response (122.1), low limit of detection, good linear fitting (R2 = 0.9892), rapid response/recovery time (5/27 s) towards 50 ppm acetone. Meanwhile, by detecting six gases, including acetone, ammonia, formaldehyde, xylene, triethylamine, and ethanol, it was found that the SnO2@CMK-3 sensor showed good selectivity to acetone. The unique nanostructure, large specific surface area, high oxygen vacancy content, and the formation of heterojunctions accounted for the good performance to acetone. These results highlighted the potential application of the SnO2@CMK-3 composite for the detection of acetone gas and presented a promising approach to prepare SMO@carbon composites for VOCs detection.

Confined growth of Cu2O quantum dots on oxygen vacancies mediated Bi24O31Br10 nanosheets for efficient tetracycline hydrochloride photodegradation driving by S-scheme mechanism

The rational design of the photocatalytic system with high charge separation efficiency is essential to the photocatalytic process. In this work, the oxygen vacancies mediated Cu2O quantum dots/Bi24O31Br10 nanosheets heterojunctions were constructed, where the concentration of oxygen vacancies was increased with the increasing amount of Cu2O. The optimized Cu2O/Bi24O31Br10 nanocomposites exhibited significantly enhanced apparent kinetic constant values toward tetracycline hydrochloride (TCH) photodegradation, showing an increase of 5.3 times compared to bare Cu2O and 2.2 times compared to pure Bi24O31Br10. By taking advantage of the inherent electronic field generated at the interface, there is a significant enhancement in charge separation efficiency, leading to an improvement in photocatalytic performance. Furthermore, a comprehensive investigation was conducted to determine the various factors that impact the efficiency of TCH removal. These factors encompassed the catalyst dosage, TCH concentration, pH level, and presence of anions. Based on the in-situ X-ray photoelectron spectroscopy (XPS), reactive oxygen species detection, as well as density functional theory calculation (DFT), the S-scheme charge transfer pathway was verified. This work contributes to the design of p-n S-scheme heterojunctions for environmental remediation.

Enhancing solid oxide electrolysis cell cathode performance through defect and bond engineering: A study on K-doped PrBaMn2O5+δ perovskites

Collaborative design of defects and bonds is a novel strategy to enhance the activity of cathode materials for solid oxide electrolysis cells (SOECs). In this study, we report the synthesis and characterization of layered PrBaMn2O5+δ (PBM) and Pr0.9K0.1BaMn2O5+δ (PKBM) materials, aimed at developing cathodes for high-temperature H2O electrolysis. The effects of K doping on the structural, physicochemical, and electrochemical properties of these materials are thoroughly investigated. The results reveal that K doping induces lattice expansion and reduces the total cation valence state in PKBM. These changes significantly increase oxygen vacancy concentration, enhancing the chemical adsorption capacity of H2O on the electrode surface and improving the H2O reduction reaction activity. Theoretical calculations support these findings, showing that K doping lowers the oxygen vacancy formation energy and strengthens H2O adsorption. Impedance analyses further demonstrate that K doping reduces the polarization resistance, thereby enhancing surface adsorption and diffusion processes. Consequently, the PKBM cathode exhibits superior electrolysis performance, achieving a current density of 739 mA/cm2 at 1.3 V and 800 °C. This strategy provides valuable insights for designing advanced cathodes for high-temperature H2O electrolysis and other electrochemical catalysis applications.

The Study of the Etching Resistance of YOF Coating Deposited by Atmospheric Plasma Spraying in HBr/O2 Plasma

Yttrium oxyfluoride (YOF) coatings with different oxygen content were prepared using atmospheric plasma spraying (APS) technology. The etching resistance of the coatings in HBr/O2 plasma was investigated. Shifts in diffraction peaks of the X-ray diffraction, along with XPS analysis conducted before and after etching, demonstrated that Br ions could replace O and F ions and fill the oxygen vacancies after exposure to HBr/O2 plasma, which is supported by the first-principles calculations. Br ions formed a protective layer on the surface of the YOF coating, slowing down further etching by Br ions. By adjusting the oxygen mass fraction in YOF powder, the oxygen vacancy concentration and Br ion filling were regulated to enhance etching resistance. YOF coatings with 6% oxygen content exhibited improved etching resistance compared to YOF coatings with 3% and 9% oxygen content. This improvement was primarily due to the increased Br ion concentration. These findings provide a new approach for developing coatings with enhanced etching resistance.

Tuning oxygen vacancy for efficient CO2 electroreduction over CeO2 supported SnO2

CO2 electroreduction is favorable in neutral or alkaline aqueous solutions, where H2O serves as the proton source, suffering from sluggish dynamics. Herein, we synthesize a series of SnO2-CeO2 with different oxygen vacancy (Ov) concentration, regulating the H2O dissociation, to synchronize with the CO2 reduction. The optimal SnO2-CeO2 catalyst, with a moderate Ov concentration, exhibits a formate Faradic efficiency of nearly 93% and maintains for more than 46 h at a current density of 100 mA/cm2. The catalyst with lower Ov concentration results in weak H2O dissociation, thus enhancing the energy barrier of *OCHO generation, while higher Ov concentration leads to excessive proton, exacerbating the hydrogen evolution reaction (HER), as supported by DFT calculation and in situ attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR). This study underscores the significance of Ov concentration in determining the ability of water dissociation over supported electrocatalysts, providing valuable insights for the development of more efficient electrocatalyst.

Impact of an annealing atmosphere on band-alignment of a plasma-enhanced atomic layer deposition-grown Ga2O3/SiC heterojunction

Gallium oxide (Ga2O3) has attracted much attention because of its notable advantages, including its low cost and a high critical breakdown field. In this study, atomic layer deposition was used to deposit high-quality Ga2O3 onto a SiC substrate with high thermal conductivity. The band arrangement of the Ga2O3/SiC heterojunction was investigated by modulating oxygen vacancies using different post-annealing atmospheres. The results demonstrated that recrystallization of Ga2O3 resulted in a good crystalline state because of the rearrangement of Ga and O atoms following high-temperature annealing. Simultaneously, the roughness of all annealed samples increased. X-ray photoelectron spectroscopy analysis revealed a significant reduction of oxygen vacancy content in samples that were annealed in an oxygen atmosphere; this is attributed to the replacement of oxygen vacancies by oxygen atoms. Conversely, oxygen vacancies increased in an oxygen-free environment. The band offsets (valence band, conduction band) were respectively determined to be (−1.03 eV, 0.5 eV), (−0.63 eV, 0.9 eV), (−1.39 eV, 0.16 eV), and (−1.32 eV, 0.22 eV) for the as-deposited sample and annealed samples with O2, N2, and Ar atmospheres. Finally, the impact that various ratios of oxygen vacancies have on the energy band structure of Ga2O3 was studied using first-principles calculations. Calculations on heterojunctions confirmed that the introduction of oxygen vacancies reduced the potential barrier at the interface and promoted the movement of electrons. Thus, this study provides valuable insights for the design and application of Ga2O3/SiC heterojunction devices.

Thermal stability and coalescence dynamics of exsolved metal nanoparticles at charged perovskite surfaces

Exsolution reactions enable the synthesis of oxide-supported metal nanoparticles, which are desirable as catalysts in green energy conversion technologies. It is crucial to precisely tailor the nanoparticle characteristics to optimize the catalysts’ functionality, and to maintain the catalytic performance under operation conditions. We use chemical (co)-doping to modify the defect chemistry of exsolution-active perovskite oxides and examine its influence on the mass transfer kinetics of Ni dopants towards the oxide surface and on the subsequent coalescence behavior of the exsolved nanoparticles during a continuous thermal reduction treatment. Nanoparticles that exsolve at the surface of the acceptor-type fast-oxygen-ion-conductor SrTi0.95Ni0.05O3−δ (STNi) show a high surface mobility leading to a very low thermal stability compared to nanoparticles that exsolve at the surface of donor-type SrTi0.9Nb0.05Ni0.05O3−δ (STNNi). Our analysis indicates that the low thermal stability of exsolved nanoparticles at the acceptor-doped perovskite surface is linked to a high oxygen vacancy concentration at the nanoparticle-oxide interface. For catalysts that require fast oxygen exchange kinetics, exsolution synthesis routes in dry hydrogen conditions may hence lead to accelerated degradation, while humid reaction conditions may mitigate this failure mechanism.

Preparation and Properties of Fe-Based Double Perovskite Oxide as Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cell.

Double perovskite oxides with mixed ionic and electronic conductors (MIECs) have been widely investigated as cathode materials for solid oxide fuel cells (SOFCs). Classical Fe-based double perovskites, due to their inherent low electronic and oxygen ionic conductivity, usually exhibit poor electrocatalytic activity. The existence of various valence states of B-site ions modifies the material's catalytic activity, indicating the possibility of the partial substitution of Fe by higher-valence ions. LaBaFe2-xMoxO5+δ (x = 0, 0.03, 0.05, 0.07, 0.1, LBFMx) is used as intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode materials. At a doping concentration above 0.1, the Mo substitution enhanced the cell volume, and the lattice expansion caused the formation of the impurity phase, BaMoO4. Compared with the parent material, Mo doping can regulate the oxygen vacancy concentration and accelerate the oxygen reduction reaction process to improve the electrochemical performance, as well as having a suitable coefficient of thermal expansion and excellent electrode stability. LaBaFe1.9Mo0.1O5+δ is a promising cathode material for IT-SOFC, which shows an excellent electrochemical performance, with this being demonstrated by having the lowest polarization resistance value of 0.017 Ω·cm2 at 800 °C, and the peak power density (PPD) of anode-supported single-cell LBFM0.1|CGO|NiO+CGO reaching 599 mW·cm-2.

Electronic Structure Modulating of W18O49 Nanospheres by Niobium Doping for Efficient Hydrogen Evolution Reaction.

Hydrogen, known for its high energy density and environmental benefits, serves as a prime substitute for fossil fuels. Nonetheless, the hydrogen evolution reaction (HER), essential in electrolysis, encounters challenges with slow kinetics and significant overpotential, which elevate costs and reduce efficiency. Thus, developing efficient electrocatalysts to reduce HER overpotential is vital to enhance hydrogen production efficiency and minimize energy consumption. Adjusting the electronic structure of transition metal oxides via elemental doping is a potent strategy to improve the effectiveness of electrocatalysts for hydrogen evolution. In this work, we synthesized a set of niobium-doped tungsten oxides (Nbx-W18O49) under anoxic conditions using a straightforward "one-pot" solvothermal approach. After doping Nb, the oxygen vacancy content inside W18O49 was increased, which induced a synergistic effect with the active sites of tungsten. In acidic environments, the hydrogen evolution activity of the Nb0.6-W18O49 electrocatalyst is second only by 20 wt % Pt/C. It attains a current density of -10 mA cm-2 at an overpotential of 102 mV. By comparison with W18O49, Nb0.4-W18O49 and Nb0.5-W18O49, Nb0.6-W18O49 demonstrates a reduced charge transfer resistance, which significantly enhances its conductivity and the speed of electron movement across interfaces. Coupled with this feature are notably faster HER kinetics. Additionally, it exhibits excellent stability, meaning it maintains its performance and structural integrity over prolonged periods and under various operational conditions. This article provides a new perspective for discovering inexpensive and efficient hydrogen evolution electrocatalyst materials.

Enhanced H2S removal efficiency using CuO/Al2O3 catalyst impregnated with Ca(NO3)2: Influence of calcination temperature and mechanistic insights

A series of Ca(NO3)2-CuxO/Al2O3 catalysts with different calcination temperatures were designed to remove H2S effectively. Experimental and characterization results indicate that the calcination temperature can influence the catalyst's specific surface area, basic sites, and oxygen vacancies (VOs) concentration, thereby promoting its desulfurization performance. The Ca(NO3)2-CuxO/Al2O3 catalyst, calcined at 230 °C, exhibits an optimal surface structure. It demonstrates optimal H2S desulfurization performance at a temperature of 60 °C and relative humidity of 60 %, achieving a removal capacity of 486.67 mg/g. The VOs in CuxO (CuO and Cu2O) induce a unique catalytic of H2O, which generates hydroxy radicals (·OH) to oxidize the H2S anion to S. The introduction of Ca2+ provides basic sites to buffer pH, and NO3- with H+ removes H2S through cyclic oxidation, significantly enhancing the desulfurization performance of the Cu-based catalyst. The CaO-CuxO/Al2O3 catalyst, calcined at 700 °C, suffers from a deteriorated catalyst structure, leading to the rapid formation of desulfurization by-products due to the presence of CaO covering the catalyst surface. This diminishes the effectiveness of Cu, significantly impairing the catalyst's desulfurization performance (150.47 mg/g). Consequently, desulfurization mechanisms of Ca(NO3)2-CuxO/Al2O3 and CaO-CuxO/Al2O3 are proposed, offering effective strategies for the design and optimization of subsequent high-efficiency catalysts.

An electrochemiluminescence sensor for ultrasensitive determination of tyrosine based on ceria nanomaterial as a novel luminophor

BackgroudRecently, optical nanomaterials have attracted much attention in the field of electrochemiluminescence (ECL). Nanostructured ceria possessed unique optical properties, and it's always used for constructing ECL sensor as catalyst for improving sensing performance, while the ECL property of ceria is rarely studied. In fact, it could be the potential candidate for applying in ECL sensors based on size and shape dependency optical property caused by the quantum scale effects. Therefore, new simple and efficient ceria nanomaterial used as luminophor for constructing the ECL sensor have aroused more research interest and motivation. (91 words). ResultsIn the work, three kinds of nanostructured ceria, ceria nano-cube (CeO2-NC), ceria nano-rods (CeO2-NR) and ceria nano-particle (CeO2-NP), have been prepared by hydrothermal method, and CeO2-NC with the less oxygen vacancy has the highest ECL signal. Moreover, how the shape affects the ECL property was investigated in detail, especially the oxygen vacancy on the surface of the ceria. The less of oxygen vacancy content of CeO2 nanomaterials is more favorable the ECL reaction. Furthermore, a novel ECL sensor was constructed based on reduced graphene oxide (rGO), Au nano-particle (AuNPs) and CeO2-NC for Tyrosine (Tyr) determination owing to the electron transform between the luminous of ceria and Tyr resulting in the cathodic ECL intensity quenched correspondingly, and it has possessed excellent sensing performance with a linear range of 0.005–20 nmol/L and the limit of detection (LOD) value of 1.7 fmol/L (141 words) Significance and noveltyThe proposed method demonstrated excellent selectivity and ultra-sensitivity toward Tyr, which had been used for the determination of Tyr in human serum successfully, possessing outstanding analytical performance. Therefore, nanostructured ceria is a new category of efficient and promising luminophore, which would open new avenues for the potential application in the field of ECL sensing for clinical diagnosis. (57 words).

Tailoring the catalytic activity of PrBaFe2O5+δ cathode material with non-transition metal In-doping for solid oxide fuel cells

Double perovskite PrBaFe2O5+δ (PBF) is a promising cathode material for solid oxide fuel cell (SOFCs) due to the favorable catalytic activity and superior electrochemical stability. Herein, to further tailor the oxygen-ion transport kinetics and electrochemical performance, unlike the typical approach through using higher valence, non-transition metal In3+ ion doping is initially investigated to partially replace Fe3+/Fe4+ site, forming the compositions of PrBaFe2−xInxO5+δ (PBFInx, x = 0, 0.05, 0.1, and 0.15). Xray diffraction (XRD) analysis indicates that PBFInx exhibit satisfactory chemical and thermal compatibility with the gadolinia-doped ceria (GDC) electrolyte. Expectedly, the polarization resistance (Rp) of PBFIn0.1 cathode is decreased by approximately 40 % and an anode-supported single cell with PBFIn0.1 cathode yields a 36 % higher peak power density (PPD) at 800 °C compared to that of PBF. Moreover, the single cell using PBFIn0.1 as the cathode can be operated stably at 0.4 A cm−2 for more than 50 h without obvious performance degradation. In addition, the X-ray photoelectron spectroscopy (XPS) results confirm that the low-valence state In3+ introduced into PBF have a positive impact on the oxygen vacancy concentration and boost the oxygen reduction reaction (ORR) activity, thus significantly enhancing the electrochemical performance of the PBF cathode. The results show that the non-transition metal In3+ ion doping is an effective method to improve the performance of the PBF cathode for SOFCs.

Anomalous resistive switching effect in La0.8Ca0.2MnO3/Nb:SrTiO3 structure

A barrier-type resistive switching (RS) unit, composed of a metal and Nb:SrTiO3 (NSTO), holds significant potential for data storage applications due to its high storage density, low operating voltage, and excellent stability. While extensive research has been conducted on conductive oxides (COs), there has been relatively less focus on the RS properties of heterogeneous structures combing CO electrodes and NSTO. Epitaxial growth of CO on NSTO is expected to yield devices with enhanced stability and repeatability. This study explores the RS characteristics of La0.8Ca0.2MnO3 (LCMO)/NSTO heterostructures through epitaxy of both conventional and anoxic LCMO films on (00 l)-oriented NSTO single crystal substrates. The results reveal that the conventional LCMO/NSTO structure exhibits a conventional counterclockwise bipolar RS (BRS) effect, while the anoxic LCMO/NSTO heterostructure demonstrates a unique clockwise (CW) BRS effect (exhibiting different RS characteristics under different applied voltages). The study concludes that the CW-BRS effect mechanism is attributed to a high concentration of oxygen vacancies (Vo) in LCMO. Under different external electric fields, Vo in LCMO and NSTO migrate to the LCMO/NSTO interface, respectively, leading to multiple changes in the interface barrier. These findings offer valuable experimental insights for utilizing CO in the field of RS applications.

Synthesis of Nd2Sn2O7 pyrochlore with different lattice disorder degrees and oxygen vacancy contents

In this study, a series of Nd2Sn2O7 pyrochlores with different lattice disorder degrees and oxygen vacancy contents were prepared via simple methods, including the sol–gel (SG) technique, glycine–nitrate combustion (GNC), coprecipitation (CP), and the hydrothermal (HT) method. Raman spectroscopy proved the most effective in identifying the lattice disorder degree and lattice defects of the pyrochlore-type composite oxides, followed by XRD, with FTIR spectroscopy as the least sensitive technique. For pure phase Nd2Sn2O7, the content of oxygen vacancies and adsorbed oxygen species follow the sequence CP > GNC > SG, which is well consistent with the lattice disorder degrees. This is because that the higher the lattice disorder of Nd2Sn2O7 pyrochlore, the weaker the Sn-O bond, making it easier to break and form oxygen vacancies. Although the HT sample exhibits the lowest disorder degree, its synergistic effect with residual SnO2 on the surface is beneficial for further enriching oxygen vacancies.

A highly-efficient peroxymonosulfate activator using a sewage sludge derived biochar supported cobalt oxide: Mechanism and characteristics

The application of biochar derived from sewage sludge (BS) in Fenton-like reactions for contaminant removal has attracted considerable attention. Herein, a BS-supported Co3O4 (BS-Co3O4) catalyst was synthesized using a simple two-step hydrothermal-calcination process to achieve highly efficient activation of peroxymonosulfate (PMS). The introduction of biochar effectively inhibited the aggregation of Co3O4 and reduced cobalt leaching. Compared to Co3O4, the mesoporous BS-Co3O4 exhibited an 8-fold increase in specific surface area (SSA) to 111.92 m2∙g−1, and a 46 %-66.4 % reduction in crystal plane size. The interaction between biochar and cobalt oxide resulted in several notable enhancements in the BS-Co3O4 composite. Specifically, there was an increase in sp2 carbon content, a 42.69 % rise in capacitance, and a 79.99 % reduction in charge transfer resistance. These improvements contributed to enhanced PMS activation performance. The BS-Co3O4 also contained a higher content of Co(II), sp2 carbon, and oxygen vacancies (OV). Co(II) played a crucial role in the redox reaction, accelerating the formation of SO4•− and 1O2 during the PMS activation process. Additionally, OV acted as electron capture centers, further promoting the generation of 1O2. Evidence from reactive species investigations and electron paramagnetic resonance (EPR) tests indicated that SO4•− and 1O2 were the main reactive radicals for eliminating tetracycline (TC). Based on the identification of TC intermediates, two potential degradation pathways were proposed, and a reduction in intermediate toxicity was observed. Experiments involving interference and repetition demonstrated that the BS-Co3O4 catalyst was stable and reusable. This work provides a solution with low metal leaching, high recycling performance, and safety for antibiotic wastewater treatment.

Construction of NiCo2O4/NiCoO2 co-embedded porous bio-carbon with rich heterogeneous interfaces for excellent bacteriostatic microwave radiation protection

To attain the stable protection against electromagnetic radiation pollution in complex bacterial environment, herein the NiCo2O4 and NiCoO2 co-embedded porous bio-carbon (PBC) with outstanding microwave absorption and anti-bacterial ability was successfully obtained via facile carbonization and immersion-annealing route. The component and microstructure of composites are both tightly affected by the synthetic temperature, which also influences the oxygen vacancy content and defect density within them. The strong interface polarizations from plentiful heterogeneous interfaces and dipole polarizations generated by defects and vacancies contribute greatly to the dielectric absorption, while the eddy-current loss and magnetic resonances have a certain effect as well. Under the matched impedance from magnetic-dielectric balance, the optimized absorption strength of prepared composite achieves −38.2 dB at 2.0 mm thickness with broad absorbing bandwidth of 7.01 GHz for only 2.31 mm. Moreover, the plentiful oxygen vacancies induced reactive oxygen species (ROS) together with heavy metal ions from nickel-cobalt ferrites can suppress the reproduction of Gram negative Escherichia coli (E. coli) and Gram positive Staphylococcus aureus (S. aureus) with anti-bacterial rates of 92.4 % and 93.2 %, respectively. The paper offers a novel insight to design dual-functional microwave absorber with excellent bacteriostatic performance for long-term using in complex bacterial environment.

Effects of La/Mn-Ceria&TiO2 heterojunction on titanium implants: Improved regenerative repair of diabetic bone with enhanced antioxidant characteristics

Hyperglycemia-induced oxidative stress (OS) plays a crucial role in implant osseointegration and often results in implant failure in patients with diabetes. Implants modified with cerium nanoparticles (CeO2-NPs) have gained significant attention owing to their remarkable oxidase-mimetic activity and therapeutic potential. Increasing the Ce3+ content and oxygen vacancy concentration in CeO2-NPs enhances the catalytic activity of CeO2-NPs. In this study, we synthesized lanthanide (La)/manganese (Mn) -doped CeO2-NPs composite coatings (La-CNPs and Mn-CNPs) on alkali-etched Ti substrates using a one-step hydrothermal method. Our findings indicate that the integration of La/Mn doping, in conjunction with a titanium dioxide carrier, augmented both the Ce3+ content and the oxygen vacancy concentration in La-CNPs and Mn-CNPs. By analyzing their electronic energy band structures, we found that La-CNPs exhibited superior catalase activity, whereas Mn-CNPs outperformed them in terms of superoxide dismutase activity. Under OS conditions, La-CNPs and Mn-CNPs (especially Mn-CNPs) markedly reduced intracellular reactive oxygen species levels in MC3T3-E1 cells, promoting their proliferation and osteogenic differentiation. Complementing these in vitro observations, in vivo trials underscored the capability of Mn-CNPs to enhance osteointegration in surrounding implants in diabetic rat models. Consequently, Mn-CNPs coatings present a promising avenue for augmenting the efficacy of implant therapies, especially in patients with diabetes.

Improving thermoelectric properties of high-entropy (Ca0.27Sr0.27Ba0.27La0.19)TiO3-δ ceramics through defect engineering by controlling the oxygen vacancy content

The current dependence on a singular optimization approach has severely impeded the further enhancement of the performance characteristics of strontium titanate-based thermoelectric materials, thereby significantly hindering their development and practical applications. This study integrates entropy engineering with defect engineering to explore the influence of increased oxygen vacancy concentrations and their interactions with other defects on the microstructure, electrical, and thermal transport properties of high-entropy (Ca0.27Sr0.27Ba0.27La0.19)TiO3-δ ceramics. These ceramics were synthesized using spark plasma sintering (SPS) and subsequently subjected to varying degrees of annealing in a reducing atmosphere. The enhancement of oxygen vacancy concentration within the ceramic did not alter its intrinsic phase structure; however, it had a significant and observable effect on grain growth, porosity, and the formation of dislocation bands. Additionally, the reduction of Ti4+ to Ti3+ was facilitated. These modifications substantially improved the electrical conductivity of the ceramics and accelerated the reduction in thermal conductivity with temperature, thereby promoting the achievement of high ZT values at elevated temperatures. Ultimately, the thermoelectric ceramic demonstrated an impressive power factor of 492 μW/(m·K2) at 1073 K, coupled with a notably low thermal conductivity of 0.31 W/(m·K) and a ZT value of 0.2. This investigation also confirms the existence of an optimal oxygen vacancy concentration that maximizes the thermoelectric performance of the ceramic material. This research underscores the capacity of the combined application of entropy engineering and defect engineering to transcend the confines of conventional single-optimization methodologies, resulting in a marked improvement in the thermoelectric performance of the material across diverse parameters.

Preparation of Zn1-xCexO resistive switching film on SS304 and its corrosion resistance mechanism in NaCl solution

The corrosion-resistant behavior of the films was investigated in conjunction with the principle of resistive switching, and the films were subjected to continuous repair by modulating the oxygen vacancies. Zn1-xCexO resistive switching film was prepared on SS304 surface by one-step hydrothermal method combined with the following heat treatment. The surface morphology, crystal structure, composition, oxygen vacancy concentration and semiconductor type of Zn1-xCexO film were determined. The corrosion resistance and resistive switching properties of Zn1-xCexO films were measured by electrochemical tests, immersion experiment and resistive switching experiment. The oxygen vacancy formation energy, surface adsorption energy and diffusion energy barrier energy of Zn1-xCexO film were calculated by density functional theory (DFT). The experimental results show that with the increasing of Ce doping concentration, the nano-flowers on the surface of Zn1-xCexO film become sparse, and the lattice constants a and c increase, the oxygen vacancy concentration of the film gradually increases, while the corrosion resistance of Zn1-xCexO film decreases. The corrosion resistance of Zn0.98Ce0.02O film is the best (99.36%). During resistive switching process, the polarization treatment will promote the conversion of Ce3+ to Ce4+ in film, reduce the formation energy and diffusion barrier of oxygen vacancies, and thus promote the formation and migration of oxygen vacancies in film and then convert the film into a low resistance state. Zn1-xCexO films can stably switching between high and low resistance states, maintaining excellent corrosion resistance, which is of great significance for expanding the application of resistance switching principles in the field of corrosion protection.