Ultrasonic Spray Research Articles

A Coherent Workflow for Elevating Transition Metal Oxide Anode Materials in Alkaline Electrolysis to Connect Insights from Micro Powder Analysis with Electrochemical Performance

Increasing environmental concerns have redirected research efforts toward sustainable energy, prominently highlighting hydrogen as a promising solution [1]. Despite considerable advancements in water electrolysis, providing efficient energy conversion and storage, there exists a gap in our comprehensive understanding of the production chain. This includes insights from commercial powder materials to electrode fabrication and their electrocatalytic behavior, representing an underexplored domain that demands closer examination.This study systematically examines transition metal oxide electrocatalysts, aiming to parameterize the process chain within the context of a coherent workflow for advancing transition metal oxide anode materials in alkaline electrolysis. This approach seeks to reveal the interdependencies and comprehend the correlations between material properties, fabrication processes, electrode structure, and the final performance of the cell. Our methodology integrates a range of complementary techniques to ensure a consistent analysis of the physical and chemical properties of the materials. Following the initial characterization of commercial micropowder through transmission electron microscopy and energy-dispersive X-ray spectroscopy, we optimized ink formulations derived from the powder using analytical centrifugation and Hansen parameter calculations [2]. Subsequently, selected inks were transferred to electrodes by coating these inks on Ni plates via ultrasonic spray deposition. We further investigated the impact of post-treatments, including vacuum annealing and surface plasma treatment, on the stability of the electrodes, particularly in terms of delamination prevention.To quantify the underlying micro features of this wide range of electrode surfaces and analyze their characteristics, we developed a framework called multistage data quantification (MSDQ). MSDQ ulitizes microscopical charcterizations such as laser microscopy and atomic force microscopy [3]. The assessed electrodes were finally tested as anodes for alkaline water electrolysis, revealing correlations between electrode properties and electrochemical activity and stability. In line with the recognized structural characteristics, our initial findings indicate that electrodes treated with plasma demonstrate reduced overpotentials and enhanced stability when compared to pristine and plasma treated electrodes, due to increased adhesion and surface properties (e.g., roughness).Our study makes a substantial contribution to the comprehensive evaluation of the alkaline water electrolysis system across its development stages, incorporating valuable insights from earlier steps to continually enhance electrode performance. Our approach is particularly advantageous in enabling the transition from laboratory-scale research to scalable processing, effectively bridging the crucial gap for practical industrial applications [4]. Ehlers, J.C., et al., "Affordable Green Hydrogen from Alkaline Water Electrolysis: Key Research Needs from an Industrial Perspective. " ACS Energy Letters, 2023. 8(3): p. 1502-1509.Bapat, S., et al., "On the state and stability of fuel cell catalyst inks. " Advanced Powder Technology, 2021. 32(10): p. 3845-3859.Jain, A., et al., "Small-Area Observations to Insight: Surface-Feature-Extrapolation of Anodes via Multistage Data Quantification. " Under review, ChemCatChemSegets, D., et al., "Accelerating CO2 electrochemical conversion towards industrial implementation." Nature communications 14.1 (2023): 7950.

Comparative Study of Anion Exchange Membranes for Application in Advanced AEM Water Electrolysers

The chemical nature of hydrogen combined with its capability to be an energy carrier for energy conversion devices with zero- emission and its higher energy density than any other commercial fossil fuel-based energy source, make it unique [1]. The International Renewable Energy Agency has identified three of the most viable technologies for producing hydrogen in large volume, namely: alkaline water electrolyzers (AWEs), proton exchange membrane water electrolyzers (PEMWEs), and anion exchange membrane water electrolyzers (AEMWEs) [2]. Among the three types of electrochemical devices the AEMWEs are the newest and most promising, because they (i) have the same slim design of the PEMWEs, (ii) can operate at high current densities, and (iii) can use non-precious catalysts [3]. The durability and efficiency of the AEMWEs systems are significantly influenced by the anion exchange membranes (AEMs), which are currently under development. In addition, the used catalysts, as well as the methods for fabrication of the membrane electrode assemblies (MEAs) also impact substantially the electrolyzer’s performance. Catalyst-coated substrate (CCS) is one of the methods for fabrication of MEAs [4], while the other used method is known as catalyst coated membranes (CCMs). The Reactive Spray Deposition Technology (RSDT) is an innovative flame-assisted method that can be used for fabrication MEAs from both types [5].In this work, CCS are fabricated by the ultrasonic spray deposition method and 5 MEAs are assembled with various AEM membranes. This approach involves the application of Platinum Group Metal (PGM) catalysts, Pt/C and as cathode and anode catalyst layers, onto a Gas Diffusion Layer (C-GDL) and a porous transport layer (Ti-PTL). As fabricated CCSs are assembled with the three state-of-the-art commercially available AEMs, namely: FAA-3, Sustainion X-37, and TM1, and their performance is evaluated. In addition, CCSs with ultra-low PGM loadings in their catalyst layers are fabricated with the RSDT method and better performance in comparison to the baseline MEAs with high PGM loadings, is achieved. This comparative study provides valuable insights into the strengths and weaknesses of each membrane type for application in AEM water electrolysers. Reference: [1] M. G. Rasul, M. A. Hazrat, M. A. Sattar, M. I. Jahirul, and M. J. Shearer, “The future of hydrogen: Challenges on production, storage and applications,” Energy Conversion and Management, vol. 272, p. 116326, Nov. 2022, doi: 10.1016/j.enconman.2022.116326.[2] D. Yang et al., “Patent analysis on green hydrogen technology for future promising technologies,” International Journal of Hydrogen Energy, vol. 48, no. 83, pp. 32241–32260, Oct. 2023, doi: 10.1016/j.ijhydene.2023.04.317.[3] D. S. Falcão, “Green Hydrogen Production by Anion Exchange Membrane Water Electrolysis: Status and Future Perspectives,” Energies, vol. 16, no. 2, p. 943, Jan. 2023, doi: 10.3390/en16020943.[4] J. E. Park et al., “High-performance anion-exchange membrane water electrolysis,” Electrochimica Acta, vol. 295, pp. 99–106, Feb. 2019, doi: 10.1016/j.electacta.2018.10.143.[5] Z. Zeng, J. Xing, L. Bonville, D. R. Dekel, R. Maric, and S. Bliznakov, “Advanced nickel-based catalysts for the hydrogen oxidation reaction in alkaline media synthesized by reactive spray deposition technology: Study of the effect of particle size,” International Journal of Hydrogen Energy, p. S0360319923013721, Apr. 2023, doi: 10.1016/j.ijhydene.2023.03.249.

(Invited) Streamlined Production of Protonic Ceramic Electrochemical Cells Via Ultrasonic Spray Coating

Thin solid oxide films are crucial for developing high-performance solid oxide-based electrochemical devices aimed at decarbonizing the global energy system. This presentation introduces ultrasonic spray coating technique (USC) for producing <10 µm thin electrolyte films, as well as uniform 4×4 cm2 oxygen electrode films, with a systematic process optimization considering solid loading rates, spray passes, and annealing temperature etc. Notably, the integrated approach highlights the versatility of USC in addressing both oxygen electrode and electrolyte fabrication challenges. The resulting protonic ceramic electrochemical cells, fabricated with these optimized parameters, exhibit remarkable electrochemical performance, structural integrity, and stability in both fuel cell and electrolysis modes. This presentation provides a holistic perspective on scalable production techniques, showcasing the potential of ultrasonic spray coating for advancing large-sized solid oxide electrochemical cells.

Tbx-Zn1-x-BDC MOF films synthesized in-situ by the aero-sol-assisted chemical vapor deposition

Tbx-Zn1-x-BDC MOF films were deposited in situ on glass substrates using the aerosol-assisted chemical vapor deposition (AACVD) technique with an ultrasonic spray pyrolysis system, with x ranging from 0 to 1. Various precursors and solvents were used in the precursor solutions, which were precisely nebulized onto the substrate. The resulting films were characterized using techniques such as x-ray diffraction, Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and Photoluminescence Spectroscopy. The findings revealed the evolution of Zn-BDC and/or Tb-BDC crystalline structures within the films and changes in the physical properties of the Metal Organic Frameworks (MOFs), such as film thickness and roughness. Moreover, these insights offer vital information for the design and control of MOF films with specific properties, highlighting their potential applications in various fields.

Effects of Au Addition to Porous CuO2-Added SnO2 Gas Sensors on Their VOC-Sensing Properties

The effects of Au addition on the acetone response of Cu2O-added porous SnO2 (pr-Cu2O-SnO2) powders, which were synthesized by ultrasonic spray pyrolysis employing polymethyl methacrylate microspheres as a template, were investigated in this study. The 3.0 wt% Au-added pr-Cu2O-SnO2 sensor showed the largest acetone response among all sensors. In addition, the magnitude of the acetone response was much larger than those of the ethanol and toluene responses. The catalytic activities of these gases over Au-added pr-Cu2O-SnO2 powders were also examined to clarify the key factors affecting their acetone-sensing properties. The Au addition increased the complete oxidation activity of all gases, and the complete oxidation activity of acetone was much higher than those of ethanol and toluene. These results indicate that the oxidation behavior during the gas-diffusion process in the sensitive Au-added pr-Cu2O-SnO2 layer of the sensors is quite important in enhancing the acetone-sensing properties.

Aftermath of Ag embedding on structural, optical, and supercapacitor electrode attributes of USP-grown CuO thin films

Here, ultrasonic spray pyrolysis method (USP) was utilized to produce pure and silver doped copper oxide nanostructures on glass substrates. Thereafter, several characterization techniques were conducted on the grown samples to delve into their morphological, structural, electrochemical, and optical aspects. The mentioned analyses were carried out by performing x-ray photoelectron spectroscopy, scanning electron microscope, X-ray diffraction, electrochemical impedance spectroscopy, galvostatic charge-discharge, cyclic voltammetry, and UV–visible spectroscopy measurements. Thus, the impact of silver impurity doping on the relevant aspects of host material were recorded as well as the features of unspoiled copper oxide films. Accordingly, the samples, as indicated by X-ray diffraction results, possessed (002) preferential plane orientation of copper oxide material along with the crystallite sizes ranging from 52.52 nm to 75.02 nm due to the imperfections caused by the silver doping. The scanning electron microscope images exhibited that the silver doping did not form significant modifications in the host material morphology where nanowire-like structures observed. The presence of the suggested materials in the films was verified by the x-ray photoelectron spectroscopy. Also, the UV–visible spectroscopy measurements detected that optical absorbance edge and bandgap energy values red shifted as a result of the impurity doping. The electrochemical supercapacitors performances of the silver doped copper oxide nanostructured thin films were inspected by using the GCD, EIS, and CV. The silver doped copper oxide films demonstrated a specific capacitance value of 66 F/g at a current density of 1 A/g in 1 M KOH electrolyte. From Nyquist plot, Rs, Rcor, Rpo, Ccor and Cc were obtained as 2.327 × 103 Ω.cm2, 43.63 × 103 Ω.cm2, 4.580 × 103 Ω.cm2, 111.5 × 10-6 S*s^a. cm-2 and 101.1 × 10-6 S*s^a. cm-2, respectively. The results indicated that the electrochemically synthesized the silver doped copper oxide electrodes can be obtained and developed as an alternative electrode material for supercapacitors (SCs).

Enhancing π-SnS thin films and fabrication of p-SnS/n-Si heterostructures through flow rate control in ultrasonic spray pyrolysis for improved photovoltaic performance

This study presents findings related to the characterization of cubic SnS (π-SnS) thin films and p-SnS/n-Si heterojunction structures produced simultaneously using the ultrasonic spray pyrolysis technique. In this context, the impact of different spray solution flow rates on the morphological, structural, optical, and electrical characteristics of the films was examined. Morphological analyses revealed that higher flow rates resulted in films with denser and smoother surfaces, approximately 6 nm in roughness. Additionally, it was observed that both the thickness and the growth rate of the films could be adjusted through the modulation of the flow rate. Structural analyses determined that the crystallite size increased and micro-strain values decreased with increasing flow rates. Optical evaluations indicated a decline in the optical band gap of the thin films from about 1.8 eV to 1.7 eV as the flow rates increased. This trend was consistently observed in the data obtained using the Tauc method and the derivative of transmission with respect to wavelength versus photon energy graphs. Electrical analyses revealed that the resistivity values of the thin films increased from 5.24 × 105 Ωcm to 1.64 × 106 Ωcm with increasing flow rates. Furthermore, I-V analyses of the Au/p-SnS/n-Si/Ag heterojunction structures indicated significant variability in key electrical properties. The saturation currents displayed a broad range, suggesting varying efficiencies in charge carrier collection across different samples. Similarly, the change of ideality factors pointed to differences in charge transport mechanisms, while the shifts in barrier heights indicated changes in junction properties with different fabrication conditions. The results of this study offer valuable perspectives for future research.

High-Performance Flexible Hybrid Silica Membranes with an Ultrasonic Atomization-Assisted Spray-Coated Active Layer on Polymer for Isopropanol Dehydration.

Organic-inorganic hybrid silica materials, incorporating an organic group bridging two silicon atoms, have demonstrated great potential in creating membranes with excellent permselectivity. Yet, the large-scale production of polymer-supported flexible hybrid silica membranes has remained a significant challenge. In this study, we present an easy and scalable approach for fabricating these membranes. By employing a sol-gel ultrasonic spray process with a single-pass method, we deposited a thin and uniform hybrid active layer onto a porous polymer substrate. We first optimized the deposition conditions, including substrate temperature, the binary solvent ratio of the silica sol, and various ultrasonic spray parameters. The resulting flexible hybrid silica membranes exhibited exceptional dehydration performance for isopropanol (IPA)/water solutions (IPA: 90 wt%) in the pervaporation process, achieving a water flux of 0.6 kg/(m2 h) and a separation factor of around 1300. This work demonstrates that the single-pass ultrasonic spray method is an effective strategy for the large-scale production of polymer-supported flexible hybrid silica membranes.

Dichloro-tin (IV) hexadeca-fluoro-phthalocyanine (F16PcSnCl2) thin film on porous silicon layers by ultrasonic spray pyrolysis, for possible application in optoelectronics devices

Phthalocyanines represent a significant class of organic semiconductors that have garnered attention for their potential applications in conducting polymers and organic electronics. The unique structural characteristics of phthalocyanines, coupled with the intriguing chemical behavior and variations in bandgap associated with different substitution sites, offer exciting prospects for designing novel application devices. In this study, we have successfully fabricated a heterostructure incorporating dichloro tin (IV) hexa deca fluoro phthalocyanine (F16PcSnCl2) on both porous silicon (PS) and crystalline silicon (c-Si). The PS substrate was prepared using metal-assisted chemical etching. To explore the optoelectronic applications, we thoroughly characterized the optical, electrical, and morphological properties of the heterostructure. F16PcSnCl2 exhibits the lowest reflectance within the visible light spectrum, making it highly advantageous for photosensitive applications that necessitate efficient light absorption, diffusion, or scattering. The morphological analysis of the F16PcSnCl2 film reveals the presence of nanosphere-type structures uniformly distributed on both PS and c-Si substrates. The absorbance spectrum exhibits three distinct bands, which serve as typical indicators of the F16PcSnCl2 complex. Several hybrid heterostructures were fabricated for electrical characterization, displaying rectifying ohmic behavior and demonstrating a photocurrent effect in the I-V curves. Notably, when the heterostructures were polarized at 1 V, a pronounced response to pulses of white light was observed in the current–time curves. Overall, the integration of organic and inorganic materials in heterostructures holds great promise for innovative applications in optoelectronics.

Study of FZO thin films deposited by ultrasonic spray: influence of precursor milling

In this work, the results of the study of ZnO:F (FZO) films deposited on glass substrates using the ultrasonic chemical spray technique are reported. For the preparation of the films, starting solutions were used at a concentration of 0.2 M of zinc acetate dihydrate [Zn(CH3COO)2.2H2O]) dissolved in a mixture of deionized water:methanol:acetic acid. The precursor was previously ground in a planetary ball mill at 500 rpm at different times. For the addition of the dopant, a 1.6 M solution of ammonium fluoride in deionized water was prepared NH4F. The atomic ratio of [F]/[F + Zn] remained constant at 30 at%. Structural characterizations by X-ray diffraction, morphological by scanning electron microscopy, optical by UV–Vis spectroscopy, and electrical by Hall effect were performed on all deposited films. From the analysis of results, the hexagonal wurtzite phase was confirmed, and a variation of the morphology was observed depending on the deposit conditions. In general, the films presented high optical transmittance in the visible region and the n-type conductivity was confirmed.

Mesoporous, anti-corrosive RuO2 thin films prepared by ultrasonic spray pyrolysis for supercapacitor application

Mesoporous, anti-corrosive RuO2 thin films prepared by ultrasonic spray pyrolysis for supercapacitor application

Improving assay feasibility and biocompatibility of 3D cyclic olefin copolymer microwells by superhydrophilic modification via ultrasonic spray deposition of polyvinyl alcohol

Sample partitioning is a crucial step towards digitization of biological assays on polymer microfluidic platforms. However, effective liquid filling into microwells and long-term hydrophilicity remain a challenge in polymeric microfluidic devices, impeding the applicability in diagnostic and cell culture studies. To overcome this, a method to produce permanent superhydrophilic 3-dimensional microwells using cyclic olefin copolymer (COC) microfluidic chips is presented. The COC substrate is oxidized using UV treatment followed by ultrasonic spray coating of polyvinyl alcohol solution, offering uniform and long-term coating of high-aspect ratio microfeatures. The coated COC surfaces are UV-cured before bonding with a hydrophobic pressure-sensitive adhesive to drive selective filling into the wells. The surface hydrophilicity achieved using this method remains unchanged (water contact angle of 9°) for up to 6 months and the modified surface is characterized for physical (contact angle & surface energy, morphology, integrity of microfeatures and roughness), chemical composition (FTIR, Raman spectroscopy) and coating stability (pH, temperature, time). To establish the feasibility of the modified surface in biological applications, PVA-coated COC microfluidic chips are tested for DNA sensing (digital LAMP detection of CMV), and biocompatibility through protein adsorption and cell culture studies (cell adhesion, viability, and metabolic activity). Kidney and breast cells remained viable for the duration of testing (7 days) on this modified surface, and the coating did not affect the protein content, morphology or quality of the cultured cells. The ultrasonic spray coated system, coating with 0.25 % PVA for 15 cycles with 0.12 A current after UV oxidation, increased the surface energy of the COC (naturally hydrophobic) from 22.04 to 112.89 mJ/m2 and improved the filling efficiency from 40 % (native untreated COC) to 94 % in the microwells without interfering with the biocompatibility of the surface, proving to be an efficient, high-throughput and scalable method of microfluidic surface treatment for diagnostic and cell growth applications.

Synthesis of AgCoCuFeNi High Entropy Alloy Nanoparticles by Hydrogen Reduction-Assisted Ultrasonic Spray Pyrolysis

Because of their high mixing entropies, multi-component alloys can exhibit enhanced catalytic activity compared to traditional catalysts in various chemical reactions, including hydrogenation, oxidation, and reduction processes. In this work, new AgCoCuFeNi high entropy alloy nanoparticles were synthesized by the hydrogen reduction-assisted ultrasonic spray pyrolysis method. The aim was to investigate the effects of processing parameters (reaction temperature, precursor solution concentration, and residence time) on the microstructure, composition, and crystallinity of the high entropy alloy nanoparticles. The characterization was performed with scanning electron microscope, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The syntheses performed at 600, 700, 800, and 900 °C, resulted in smaller and smoother spherical particles with a near-equiatomic elemental composition as the temperature increased to 900 °C. With 0.25, 0.1, and 0.05 M precursor solutions, narrower size distribution and uniform AgCoCuFeNi nanoparticles were produced by reducing the solution concentration to 0.05 M. A near-equiatomic elemental composition was only obtained at 0.25 and 0.05 M. Increasing the residence time from 5.3 to 23.8 s resulted in an unclear particle microstructure. None of the five metal elements were formed in the large tubular reactor. X-ray diffraction revealed that various crystal phase structures were obtained in the synthesized AgCoCuFeNi particles.

Building a Layer-Structured Aluminum/Graphene Composite with Significant Improvement in Electrical Conductivity.

Aluminum (Al) and its alloys are widely used in various fields due to their excellent physical properties. Although many efforts have been made to fabricate an Al-based composite, they usually results in a significant decrease in electrical conductivity. Herein, a special layer-structured Al/graphene (Gr)/Al composite was successfully designed and fabricated through a facile method using the ultrasonic spraying of graphene powder with alumina removal and a subsequent vacuum hot-pressing process. The as-obtained Al/Gr/Al composite presents a significantly enhanced electrical conductivity of 66% IACS, which is much higher than that of other reported Al-based composites, while it still maintains similar mechanical properties. This work provides a new strategy for the development of highly conductive Al-based composites, which would be very useful and important for practical applications.

ZnMgO Thin Films by Ultrasonic Spray Pyrolysis: Modulation of Optical and Electrical Properties by Post‐annealing and Magnesium Composition

ZnMgO semiconductor is of major interest in sustainable thin‐film solar cells in order to replace buffer layers based on nonabundant or toxic elements. In addition, it has the potential 1) to allow optimal band alignment with absorbers such as CIGS, CZTS, and Cu2O; 2) to have high transparency; 3) to have adjustable properties for use as a window or buffer layer; and 4) to be deposited using low‐cost and energy‐efficient techniques such as ultrasonic spray pyrolysis. This study focuses on modulating ZnMgO properties with the optimization of the ultrasonic spray pyrolysis and post‐annealing parameters. Optical transmission, X‐ray diffraction, and van der Pauw/Hall effect measurements are used to study the material properties. Thin films with a strong &lt;002&gt; preferred orientation are obtained with large crystallite size (42–80 nm), high transparency (&gt;90%), a bandgap increase from 3.28 to 3.34 eV with magnesium composition and annealing, an optimal Urbach energy of 0.068 eV, and electrical properties modulated by magnesium composition and annealing with resistivity varying from 6.520 Ωcm down to 0.022 Ωcm and a carrier concentration from 4.8 × 1017 up to 1.4 × 1020 cm−3.

Ion migration and dark current suppression in quasi-2D perovskite-based X-ray detectors.

Cesium-based lead-free double perovskite materials (Cs2AgBiBr6) have garnered significant attention in the X-ray detection field due to their environment friendly characteristics. However, their substantial ion migration properties lead to large dark currents and detection limits in Cs2AgBiBr6-based X-ray detectors, restricting the detection performance of the device. In terms of process technology, ultrasonic spraying is more suitable than a spin-coating method for fabricating large-area, micron-scale perovskite thick films, with higher cost-effectiveness, which is crucial for X-ray detection. This work introduces a BA+ (BA+ = CH3CH2CH2CH2NH3 +, n-butyl) source into the precursor solution and employs ultrasonic spraying to fabricate quasi-two-dimensional structured polycrystalline (BA)2Cs9Ag5Bi5Br31 perovskite thick films, developing a low-cost, eco-friendly X-ray detector with low dark current density and low detection limit. Characterization results reveal that the ion migration activation energy of (BA)2Cs9Ag5Bi5Br31 reaches 419 meV, approximately 17% higher than that of traditional three-dimensional perovskites, effectively suppressing perovskite ion migration and subsequently reducing the dark current. The (BA)2Cs9Ag5Bi5Br31-based X-ray detectors exhibit high resistivity (about 1.75 × 1010 Ω cm), low dark current density (66 nA cm-2), minimal dark current drift (0.016 pA cm-1 s-1 V-1), and detection limit (138 nGyair s-1), holding considerable promise for applications in low-noise, low-dose X-ray detection.

Altering the physical properties of NiO thin films grown through the ultrasonic spray pyrolysis method by incorporating impurity lead dopants

The technology of p-type transparent semiconductors is utilized in various fields, and enhancing their performance holds industrial significance. Thus, improving the versatility and efficiency of the p-type transparent conducting oxides (TCO) has become critical for the semiconductor industries and technologies. To be used as hole carrier layes in optoelectronic devices, this study aimed to modify the physical features of nickel oxide (NiO) through a doping approach which may broaden and strengthen the usage of NiO. A cost-effective ultrasonic pyrolysis spray technique was employed for pure and lead (Pb) doped nickel oxide thin film production. The influence of the lead concentration on optical, structural, and morphological traits of the NiO nanostructures was examined via various analyses, including energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), Photoluminescence, UV–visible spectroscopy, X-Ray Diffraction, and Raman spectroscopy, were utilized to investigate the optical and structural characteristics of these films. In correlation, the X-Ray Diffraction results indicated that the Pb doping induced strain and altered lattice parameters of the grown nanostructures while the cubic phase of NiO maintained. The crystallite size of NiO samples ranged from 31.49 nm to 18.75 nm based on Pb doping concentration which was notably influenced by species and doping content. The UV–vis measurements demonstrated that optical parameters, such as optical band gap, were sensitive to Pb doping ratios. The Raman spectrum analysis confirmed the successful incorporation of Pb ions into NiO. Additionally, the intensity of the PL spectra decreased with increasing Pb content, offering potential applications as window layers in solar cells, smart windows, and other optoelectronic devices.

The Characterization of Zn1-XCoxO Thin Films Synthesized by Ultrasonic Spray Deposition with Controlled Visible Light Absorption

The Characterization of Zn_1-XCo_xO Thin Films Synthesized by Ultrasonic Spray Deposition with Controlled Visible Light Absorption

In situ XRD and operando XRD-XANES study of the regeneration of LaCo0.8Cu0.2O3 perovskite for preferential oxidation of CO

Combinations of perovskite-type oxides with transition and precious metals exhibit remarkable regenerating properties that can be exploited for catalytic applications. The objective of the present work was to study the structural changes experienced by LaCo0.8Cu0.2O3 under reducing/oxidizing atmosphere (redox) and Preferential Oxidation of CO (PrOx, with high H2 concentration) conditions and their reversibility. LaCo0.8Cu0.2O3 was prepared by ultrasonic spray combustion and was characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Structural changes were followed by operando XRD and XAS. Metallic Co and Cu were segregated under both sets of reducing conditions and re-dissolved into the perovskite upon oxidation at 500 °C. Simultaneously, the perovskite-type oxide disappeared under reducing conditions and formed again upon high-temperature oxidation. The effects of this reversible reduction/dissolution of B-site metals on catalyst structure and activity were studied concerning the catalytic process of PrOx. The active phases of cobalt and copper oxides suffer a reduction during the PrOx reaction due to the high H2 concentration; thus, the application of an intermediate oxidation treatment can regenerate the catalytic system and the perovskite can be used for several cycles of reaction and regeneration. In contrast, when this intermediate oxidation treatment is not applied, the catalytic performance decreases in successive activity cycles.

A biodegradable polymer stent with high radial performance: Potential for treatment of portal vein stenosis

AbstractBiodegradable polymer stents have a wide application prospect in the treatment of vascular stenosis diseases. However, weak radial performance of polymer stents hinders the treatment of the diseases with high demand for radial supporting, such as portal vein stenosis. According to previous research, the constraint mode between monofilaments is a key factor that affects the radial performance of polymer braided stent. In this work, a series of Poly(l‐lactic acid) (PLLA) stents with the elastomer coating were prepared by ultrasonic spraying process to realize the constraints of monofilament cross points. The results are showed that the radial stiffness and peak force of the coated stent are significantly increased, up to 28 and 35 times higher than that of the bare stent. It is found that the cross points are constrained by the coating, which improves the constraining force between the monofilaments resulting in the increase of the radial force during the deformation process. More importantly, the mechanism of action between the radial force of the coated stent and the mechanical performance of elastic coating has been proposed, revealing a significant positive correlation between them. The radial force of the coated stent could be quantitatively regulated by the six‐arm poly(l‐lactide‐co‐ε‐caprolactone) (6SPLCL) coating cross‐linked by Hexamethylene diisocyanate (HDI) in different proportions. Finally, we build a mechanical model of stents and find that there is a consistency between the theoretical curve and the actual curve trend. This provides further research and expands the application scope for improving the radial supporting performance of the biodegradable polymer stent.