Substrate Morphology Research Articles

Nanoarchitectonics for Ultrathin Gold Films Deposited on Collagen Fabric by High-Power Impulse Magnetron Sputtering.

Gold nanoparticles conjugated with collagen molecules and fibers have been proven to improve structure strength, water and enzyme degradation resistance, cell attachment, cell proliferation, and skin wound healing. In this study, high-power impulse magnetron sputtering (HiPIMS) was used to deposit ultrathin gold films (UTGF) and discontinuous island structures on type I collagen substrates. A long turn-off time of duty cycle and low chamber temperature of HiPIMS maintained substrate morphology. Increasing the deposition time from 6 s to 30 s elevated the substrate surface coverage by UTGF up to 91.79%, as observed by a field emission scanning electron microscope. X-ray diffractometry analysis revealed signature low and wide peaks for Au (111). The important surface functional groups and signature peaks of collagen substrate remained unchanged according to Fourier transform infrared spectroscopy results. Multi-peak curve fitting of the Amide I spectrum revealed the non-changed protein secondary structure of type I collagen, which mainly consists of α-helix. Atomic force microscopy observation showed that the roughness average value shifted from 1.74 to 4.17 nm by increasing the deposition time from 13 s to 77 s. The uneven surface of collagen substrate made quantification of thin film thickness by AFM difficult. Instead, UTGF thickness was measured using simultaneously deposited glass specimens placed in an HiPIMS chamber with collagen substrates. Film thickness was 3.99 and 10.37 nm at deposition times of 13 and 77 s, respectively. X-ray photoelectron spectroscopy showed preserved substrate elements on the surface. Surface water contact angle measurement revealed the same temporary hydrophobic behavior before water absorption via exposed collagen substrates, regardless of deposition time. In conclusion, HiPIMS is an effective method to deposit UTGF on biomedical materials such as collagen without damaging valuable substrates. The composition of two materials could be further used for biomedical purposes with preserved functions of UTGF and collagen.

A review of the application of green walls in the acoustic field

Green wall technology, including green façades and living walls, presents a promising solution to encounter the negative impacts of noise pollution. Research and development of green walls are steadily progressing in multiple fields, including but not limited to the environmental, social, and economic areas. Compared to other themes, the number of acoustic studies of green walls is relatively low and lacks relevant review papers. The purpose of this paper is to give a systematic review of the application of green walls in the acoustic field and clarify the key factors that influence the acoustic performance of green walls and the main obstacles that obstruct the broader application of green walls. A total number of 34 papers published in the past 10 years are reviewed. This study identifies that the acoustic applications of green walls are mainly in four aspects, namely laboratory applications, outdoor applications, indoor applications, and audio-visual applications. Vegetation morphology and properties of substrates are the two crucial factors determining green facades and living walls’ acoustic properties, respectively. High installation, operation, and maintenance costs and plant-induced problems are recognized as the main obstructions. A few possible topics are recommended for future study as well.

Preparation and Application of Sol-Gel Polishing Pad for Polishing CVD Single Crystal Diamond at High Speed

A new polishing pad based on the sol-gel (SG) technique is fabricated and can polish the single crystal diamond (SCD) substrate at high speed. In this work, the base material, fillers, and coating height of the polishing pad are selected. Pressed polymer fiber is used as the base material, talcum powder is chosen as filler, and the coating height of the gel formulation system on the surface of the base material is between 20 and 40 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>. The surface morphology of SCD substrate was observed with a 3D optical surface profiler. The surface roughness decreased from 78.024 nm to 6.126 nm in 2 h and the material removal rate of the SCD (100) was about 135 nm/h. The Raman spectroscopy result shows that there was phase transformation on the surface of the SCD substrate after polishing. The material removal mechanism was proposed based on the result. During the scratch of the diamond abrasive, the diamond on the surface of the SCD substrate was transformed into amorphous carbon. Then the amorphous carbon was removed mechanically. The new gel polishing pad can polish the SCD substrate with high efficiency.

Thermal stability of cobalt oxide thin films and its enhancement by cerium oxide

Thermal stability of Co3O4 and CeOx-Co3O4 thin films prepared by various “dry” physical techniques is investigated. A model system is represented by well-ordered Co3O4(111)/Ir(100), more realistic and industrially relevant Co3O4 thin films were grown by magnetron sputtering and direct oxidation of cobalt. In all cases, combined systems with non-continuous cerium oxide overlayer were prepared and compared to pristine oxides. The thin films were subjected to thermal annealing under vacuum and monitored by X-ray photoelectron spectroscopy (XPS), microscopy (STM or SEM) was used to observe the surface morphology. Thermal reduction of Co3O4 spinel structures to CoO and, eventually, metallic Co depends substantially on layer morphology and type of substrate. Thermal stability of the well-ordered model system is significantly higher than for the high surface area oxides deposited by magnetron sputtering or grown by direct oxidation. In the reduction process, inevitable in many applications utilizing Co3O4, cerium adlayer can act as an efficient stabilizing component, protecting cobalt oxide against reduction and decomposition. There is a temperature dependent synergistic interplay between cerium and cobalt oxides via oxygen transfer involving Co2+/Co3+ and Ce4+/Ce3+ redox pairs. Thermal activation can lead to a formation of surface mixed spinel with higher thermal stability in reducing environments.

Engineering the Morphology and Microenvironment of a Graphene-Supported Co-N-C Single-Atom Electrocatalyst for Enhanced Hydrogen Evolution.

Graphene-supported single-atom catalysts (SACs) are promising alternatives to precious metals for catalyzing the technologically important hydrogen evolution reaction (HER), but their performances are limited by the low intrinsic activity and insufficient mass transport. Herein, a highly HER-active graphene-supported Co-N-C SAC is reported with unique design features in the morphology of the substrate and the microenvironment of the single metal sites: i) the crumpled and scrolled morphology of the graphene substrate circumvents the issues encountered by stacked nanoplatelets, resulting in improved exposure of the electrode/electrolyte interfaces (≈10 times enhancement); ii) the in-plane holes in graphene preferentially orientate the Co atoms at the edge sites with low-coordinated Co-N3 configuration that exhibits enhanced intrinsic activity (≈2.6 times enhancement compared to the conventional Co-N4 moiety), as evidenced by detailed experiments and density functional theory calculations. As a result, this catalyst exhibits significantly improved HER activity with an overpotential (η) of merely 82mV at 10mA cm-2 , a small Tafel slope of 59.0mV dec-1 and a turnover frequency of 0.81 s-1 at η= 100mV, ranking it among the best Co-N-C SACs.

Versatile CMPs as platforms to support Ag nanocatalysts for nitrophenol hydrogenation in continuous flow-through process

4-nitrophenol (4-NP) in industrial wastewater is harmful to both ecological environment and human health even in the very low concentration in the environment. Catalytic hydrogenation, which converts toxic pollutants from wastewater into high-value industrial feedstocks, is a coveted treatment option, but the design of suitable catalysts has been a challenge in the field. In this work, the functionalized conjugated microporous polymers (CMPs) anchored Ag nanocatalysts could effectively catalyze the hydrogenation of 4-NP in wastewater to 4-aminophenol (4-AP) with the rate constant k of 0.01544 s−1. We further optimized the morphology of the CMP substrate to stabilize Ag nanocatalysts and integrated the composite into a modular unit for continuous flow wastewater treatment with an outstanding permeation flux of 1603 L m−2h−1 (LMH). These findings provide an effective strategy to design noble metal catalysts for catalytic hydrogenation and could potentially be modularized for use in mountainous and isolated communities.

Influence of Silicon Substrate Surface Finish on the Screen‐Printed Silver Metallization of Polysilicon‐Based Passivating Contacts

Passivated contact based on a thin interfacial oxide and a highly doped polysilicon layer has emerged as the next evolutionary step to increase the efficiencies of industrial silicon solar cells. To take maximum advantage from this layer stack, it is vital to limit the losses at the metal polysilicon interface, which can be quantified as metal polysilicon recombination current density (J0met) and contact resistivity. In cell concepts, wherein a large variety of silicon substrate surface finish can be obtained, it is essential to know how the surface finish affects theJ0metand contact resistivity. Herein, commercially available fire through silver paste and the metal‐polysilicon recombination current densities and contact resistivity are used for three different silicon substrate surface finishes, namely: planar or saw damage etched (SDE), chemically polished in acidic solution and alkaline pyramidal textured. Contact resistivity values below 3 mΩ cm2withJ0metin order of the recombination current density of the doped region (J0pass) are obtained for samples with planar surface for both 150 and 200 nm n+polysilicon layer thicknesses. The results presented in this work show that the samples with flat substrate morphology outperform the samples with textured surfaces.

Tungsten carbide molds for precision glass molding process: Mechanism of high-temperature degradation

Tungsten carbide (WC) is a well-established material used in glass molding field due to its low thermal expansion and high compressive strength at elevated temperatures. During glass molding process, the WC mold has to withstand thousands of thermo-mechanical coupled interactions in the aerobic environment. Understanding the degradation mechanism of WC substrate during precision glass molding is very important for the design and preparation of protective coatings and the optimization of glass molding process. In this study, surface failure analysis of WC substrate was carried out using barrel compression test and ball-to-disk friction test. The microstructures, element compositions, surface morphology of the WC substrates were measured by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and white light interferometer (WLI). Damaging phenomena such oxidation, interdiffusion, spallation, glass sticking, and surface roughening on the WC substrate were observed. The experimental results showed that the WC substrate degraded very rapidly at above 600 °Cand air environment. The fundamental degradable reason of WC substrate is the oxidation, which directly leads to the decrease of the material strength, the aggravation of the wear, occurring of the glass sticking, and the increase of surface roughness. Furthermore, the WC mold microhole array without protective coatings can be used to fabricate the glass microlens array in a suitable glass molding environment. This work provides engineering guidance for the fabrication of glass optics during glass molding process.

Morphological variation in the distal phalanges of the springbok, Antidorcas marsupialis (Zimmermann, 1780) (Mammalia: Bovidae)

A comparative study of distal phalanges belonging to adult springbok individuals shows distinctive morphological differences between the subspecies Antidorcas marsupialis marsupialis and Antidorcas marsupialis hofmeyri, most notably reflected by significant lengthening of the sole of the latter. Results were derived from comparative osteomorphological techniques, using standard anatomical nomenclature for descriptions and parametric statistics for measurements and dimensions. The configuration in A. m. hofmeyri proved useful for distinguishing between the two subspecies. The findings suggest that the osteometrical differences observed in the distal phalanges relate to different habitats occupied by the species. Significance:Infraspecific morphological variation exhibited by distal phalanges in Antidorcas marsupialis is significant. The results lay the groundwork for further testing of relationships between functional morphology of foot bones and substrate in bovids.

Improving tribological properties and shear stability of base lubricant using Eichhornia crassipes carboxylmethyl cellulose polymer under different conditions

In response to the global environmental issues over inorganic additives in lubrication process in solving friction and wear challenges. There is growing interest in the development of polymer additives, particularly bio-polymer, to address the issues given by friction and wear of contact surfaces exposed to boundary and mixed lubrication regimes. The investigation employed a unidirectional ball on disc tribo-tester machine. Using rapeseed lubricant as a base oil sample, this study examined the effect of bio-based Eichhornia crassipes carboxylmethyl cellulose (EC-CMC) polymer to inorganic polyphosphate as well as mixing the two to determine their synergetic and antagonistic effect on reducing friction and wear. The additives were tested for tribological enhancement in terms of friction and wear reduction, and load-carrying effect. Scanning Electron Microscope (SEM) and energy dispersive x-ray (EDX) spectroscopy were used to examine the substrate morphology and elemental distribution of worn surfaces. Introducing 1 wt% EC-CMC, 1 wt% polyphosphate, and 1 wt% EC-CMC + 1 wt% polyphosphate into the base lubricant resulted in improved lubricant performance and reduced friction and wear. However, as compared to base rapeseed oil, the polyphosphate sample provided the best friction (44.8%), while EC-CMC gives better wear reduction (0.3073). The higher the operating capacity, the better the tribological properties of nanoparticles, according to the findings. The best tribofilm creation performance, notably with EC-CMC, is achieved when a load of 100 N is applied, resulted in outstanding tribological performance. When compared to polyphosphate, the strong and efficient nature of EC-CMC results in excellent shear stability.

Performance Enhancement and Comparison of Graphene Field Effect Transistor Devices Coated with HMDS Layer

Graphene-based devices show good transfer characteristics, which depend upon the surface morphology of the material and substrate. During fabrication of the device, the substrate morphology is disturbed inappropriately by the surface contamination. In the present study, monolayer Graphene Field Effect Transistor (GFET) has been driven with hydrophobic Hexamethyl Disilazane (HMDS) layer. The HMDS layer is dehydrated before and after the exfoliated monolayer graphene, and the electrical characteristics were measured. The transfer curve of the HMDS coated graphene device demonstrates excellent FET characteristics and prevents contamination from the atmosphere under ambient conditions. Fabrication of GFET device on the hydrophobic substrate enhances the effective ambipolar behavior. It is beginning with an excellent platform and user-friendly device for biosensing applications.

Investigation of the surface optimization of β-Ga2O3 films assisted deposition by pulsed MOCVD

β-Ga2O3 films were deposited on (-201) homo-substrates by MOCVD. All films were deposited at 800 °C, and TEGa and high-purity O2 were used as Ga and O sources, respectively. The Ga source flow rate significantly influenced the surface morphology. A relatively flat surface was obtained under the flow rates of TEGa and O2 were 40 and 2100 sccm, respectively, with a fine step structure covering the entire surface. The substrate morphology can be greatly improved after cleaning with HF/H2O2 and thermally annealing, promoting the surface flatness of the epilayer. On this basis, a buffer layer assisted by pulsed MOCVD was inserted between the substrate and the epilayer, and the RMS roughness of the epilayer was further reduced to below 1 nm. Continue to deposited the substrate-buffer layer-epilayer structure, reasonably optimized the growth pressure, O2 and TEGa flow rates, successfully realized a higher flatness surface.

Primary Mechanical Modification to Improve Performance of Miscanthus as Stand-Alone Growing Substrates

Selecting proper mechanical processing can improve performance of miscanthus substrates. We studied the effects of mechanical processing methods on substrate morphology, hydrological properties, pH, and nitrogen immobilization. Miscanthus × giganteus biomass was processed into field chips (FC, forage harvester), shreds (S5, mechanical fraying machine through a 5-mm screen) and chips (C15, C10, C5 and C3, hammermill with screen size of 15, 10, 5, or 3 mm). Processed miscanthus materials were also tested as propagation substrates for Chinese cabbage seedlings. Results showed that particle size distribution of miscanthus substrates formed four groups in ascending order of particle size: C3 &lt; C5 &lt; (C10, C15, S5) &lt; FC. The finer miscanthus substrates had higher water holding capacity following the same groupings in particle size. The hydrophobicity of processed miscanthus was low and reversible, with the increasing order of risk as C3 &lt; C5 &lt; C10, C15 &lt; S5, FC. All miscanthus substrates had similar and low pH buffering capacity. Nitrogen immobilization was similar among miscanthus substrates. The seedlings in miscanthus substrates had similar germination rates but a lower biomass compared to those grown in peat and coir. Primary mechanical modification of miscanthus offers opportunities for different sizes of substrate materials with few changes to the physical or chemical properties tested in this work.

An ultrapermeable thin film composite membrane supported by “green” nanofibrous polyimide substrate for polar aprotic organic solvent recovery

The preparation of polymeric-based thin film composite (TFC) membrane with high permeance and superior solvent resistance in organic solvent nanofiltration (OSN) applications always involves the consumption of toxic chemicals or high energy, which does not meet the requirements of green chemistry. In this work, intrinsic insoluble polyimide (PI) nanofiber substrates were obtained by a two-step method including electrospinning of poly (amic acid) synthesized by polycondensation reaction between various monomers and subsequent thermal imidization, and the optimized one with low thermal imidization temperature was employed as substrate for TFC membrane in strong polar aprotic solvents recovery, therefore achieving the green process. The effects of different dianhydride and diamine monomers and different thermal imidization temperatures on the solvent resistance and microscopic morphology of nanofiber substrates are also studied. The optimized monomers in this work contribute to a low-temperature imidization of PI nanofiber substrate. The solvent permeance of corresponding TFC OSN membrane with the insoluble PI nanofiber substrate reaches up to 11.2 L m −2 h −1 bar −1 with 99.7% rejection in rose bengal/DMF system, and good long-term stability. This work provides potential guidelines for developing next-generation OSN membranes under a green process. • Insoluble polyimide (PI) nanofibrous substrate was prepared facilely with low-temperature thermal imidization. • A green modification without toxic chemical solvent involved is applied. • PI nanofibrous substrate can withstand strong polar aprotic solvents for more than three months. • The high porosity and interconnected pores endow substrate superior solvent permeance. • TFC membrane exhibits outstanding OSN performance and long-term stability.

The Substrate Morphology Effect for Sulfur-Rich Amorphous Molybdenum Sulfide for Electrochemical Hydrogen Evolution Reaction

Amorphous molybdenum sulfide (MoSx) is a promising material for hydrogen evolution reaction (HER) due to its nearly zero hydrogen adsorption free energy at the sulfur (S) edge-sites. To prepare more efficient MoSx-based electrocatalysts, new attempts are required to increase the exposure of the MoSx lateral size and, therefore, increase the S atom’s contents. The majority of studies reported in the literature investigate MoSx over conductive substrates. However, MoSx can be electrodeposited over inexpensive and chemically stable platforms, such as semiconductors. This work presents the semiconductor substrate morphology effect for prepared sulfur-rich MoSx for electrochemical hydrogen evolution reaction. The electrodes are prepared by cyclic voltammetry with 25 cycles over TiO2 film and TiO2 nanotubes (TiO2NT) substrates. The MoSx deposit on TiO2NT presents an increase S atoms contents and exhibits excellent HER activity with a low overpotential of 93 ± 7.5 mV to reach −10 mA cm−2 and a higher exchange current density equal to 91 μA cm−2, and a smaller Tafel slope of 43 mV dec−1.

Electronic Metal–Support Interaction Modulation of Single‐Atom Electrocatalysts for Rechargeable Zinc–Air Batteries

High-performance oxygen electrocatalysts play a key role in the widespread application of rechargeable Zn-air batteries (ZABs). Single-atom catalysts (SACs) with maximum atom efficiency and well-defined active sites have been recognized as promising alternatives of the present noble-metal-based catalysts for oxygen reduction reaction and oxygen evolution reaction. To improve their oxygen electrocatalysis activities and reveal the structure-activity relationship, many advanced synthesis and characterization methods have been developed to study the effects of 1)coordination and electronic structure of the metal centers and 2) morphology and stability of the conductive substrates. Herein, a detailed review of the recent advances of SACs with strong electronic metal-support interaction (EMSI) for rechargeable ZABs is provided. Great emphasis was placed on the EMSI forms and design strategies. Moreover, the importance and the impact of the atomic coordinating structure and the substrates on the oxygen electrocatalytic activity and stability are highlighted. Finally, future directions and perspectives on the development of SACs are also presented.

Nanoscale engineering of ring-mounted nanostructure around AAO nanopores for highly sensitive and reliable SERS substrates

Surface-enhanced Raman scattering (SERS) is recognized as one of the most favored techniques for enhancing Raman signals. The morphology of the SERS substrate profoundly affects molecular Raman spectra. This study aimed to construct a ring-mounted nanostructured substrate via liquid–liquid two-phase self-assembly incorporated with anodic aluminum oxide (AAO) membrane transfer techniques. High-density nanoparticles (NPs) assembled on AAO membranes were ascribed to reduce the diameters of the nanopores, with Au–Ag alloy NPs to regulate the dielectric constant so as to reveal the local surface plasmon resonance tunability. SERS engineered in this way allowed for the fabrication of a ring-mounted nanostructured substrate where the distribution density of NPs and dielectric constant could be independently fine-tuned. High SERS activity of the substrate was revealed by detecting the enhanced factor of crystal violet and rhodamine 6G molecules, which was up to 1.56 × 106. Moreover, SERS of thiram target molecules confirmed the supersensitivity and repeatability of the substrate as a practical application. The results of this study manifested a low-cost but high-efficiency ring-mounted nanostructured SERS substrate that might be suitable in many fields, including biosensing, medical research, environmental monitoring, and optoelectronics.

The Influences of Carbon Substrate's Morphology on the C/G-C3n4 Composite's Photocatalytic Activities Under Different Wavelengths Illumination and its Purification Capacity in the Weak Uv Underwater Enviorment

The Influences of Carbon Substrate's Morphology on the C/G-C3n4 Composite's Photocatalytic Activities Under Different Wavelengths Illumination and its Purification Capacity in the Weak Uv Underwater Enviorment

Design and fabrication of bimetallic plasmonic colloids through cold nanowelding.

The integration of Au and Ag into nanoalloys has emerged as an intriguing strategy to further tailor and boost the plasmonic properties of optical substrates. Conventional approaches for fabricating these materials via chemical reductions of metal salts in solution suffer from some limitations, such as the possibility of retaining the original morphology of the monometallic substrate. Spontaneous nanowelding at room temperature has emerged as an alternative route to tailor Au/Ag nanomaterials. Herein, we perform a thorough study on the cold-welding process of silver nanoparticles onto gold substrates to gain a better understanding of the role of different variables in enabling the formation of well-defined bimetallic structures that retain the original gold substrate morphology. To this end, we systematically varied the size of silver nanoparticles, dimensions and geometries of gold substrates, solvent polarity and structural nature of the polymeric coating. A wide range of optical and microscopy techniques have been used to provide a complementary and detailed description of the nanowelding process. We believe this extensive study will provide valuable insights into the optimal design and engineering of bimetallic plasmonic Ag/Au structures for application in nanodevices.

Characterization of microporous PP/PE nonwoven mats surface modified by deposition of electrospun nanofibers

This study investigates the effect of surface modification by deposition of electrospun fibers on properties and performance of three different microporous polypropylene/polyethylene (PP/PE) commercial nonwoven membrane supports (Novatexx 2430, 2465 and 2473). Polyamide (nylon 6) nanofiber webs with a small number of defects and fibers of about 100 nanometer diameter were successfully deposited onto a surface of the selected membrane supports. FESEM was used to examine microstructure and morphology of the unmodified substrates and the prepared composite two-layer membranes. DSC was applied to investigate thermal stability and FT-IR analysis to confirm the chemical composition of the studied membranes. Saline water permeability tests of the prepared two-layer composite membranes were carried out. The largest pressure difference was measured for PA nanofiber/Novatexx 2430 sample, which was ascribed to a denser net structure of the membrane support and possibly to the newly formed layer of dissolved salts on the membrane surface.