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Low-cost, noble metal-free and environmentally friendly potassium glasses constitute a new class of promising catalysts for soot combustion. The effect of doping of potassium silicate glasses with aliovalent metals of prominent redox properties (Mn, Fe, Co, Ni, Cu, Ce) on their catalytic performance in soot combustion was investigated. A series of glasses were synthesized by the melt-quenching method and characterized in terms of composition, structure, and morphology by a plethora of techniques. The structural verification by XRD, FTIR, and RS confirmed the amorphous structure of all investigated samples. High hydroxylation and carboxylation of the surface of glassy materials were observed by DRIFT. The chemical state of metal additives in the doped samples was determined by XPS and UV/vis-DR as Mn2+/3+, Fe3+, Co2+/3+, Ni2+, Cu+/2+, and Ce3+/4+. The typical morphology of glasses obtained by the high-temperature method was observed in SEM images. Thermal stability tests by SR-TAD permitted us to order the dopants as follows: Cu > undoped > Co Mn > Ni > Fe Ce, corresponding to a decreasing stability of potassium in the investigated glasses. Catalytic activity was investigated under both tightand loose contactconditions, in an atmosphere of NO or without this additive. The investigated materials exhibited high activity in soot combustion (T50= 359–386 °C for tight contactand 442–500 °C for loose contact). The most promising dopants were Cu and Co, based on their activity and potassium stability. The low surface concentration of redox metals suggested that they influenced activity towards the modification of the glass structure rather than playing a role of active centers in the soot oxidation. Those dopants also influenced the formation and stability of potassium carbonates on the surface of the investigated glasses. A correlation between the observed thermal stability of surface potassium species and catalytic activity was established.

Emerging manufacturing technologies make it possible to design the morphology of electrocatalysts on the nanoscale in order to improve their efficiency in electrolysis processes. The current work investigates the effects of electrode-attached hydrogen bubbles on the performance of electrodes depending on their surface morphology and wettability. Ni-based electrocatalysts with hydrophilic and hydrophobic nanostructures are manufactured by electrodeposition, and their surface properties are characterized. Despite a considerably larger electrochemically active surface area, electrochemical analysis reveals that the samples with more pronounced hydrophobic properties perform worse at industrially relevant current densities. High-speed imaging shows significantly larger bubble detachment radii with higher hydrophobicity, meaning that the electrode surface area that is blocked by gas is larger than the area gained by nanostructuring. Furthermore, a slight tendency toward bubble size reduction of 7.5% with an increase in the current density is observed in 1 M KOH.

The development of topography plays an important role when low-energy projectiles are used to modify the surface or analyze the properties of various materials. It can be a feature that allows one to create complex structures on the sputtered surface. It can also be a factor that limits depth resolution in ion-based depth profiling methods. In this work, we have studied the evolution of microdendrites on poly(methyl methacrylate) sputtered with a Cs 1 keV ion beam. Detailed analysis of the topography of the sputtered surface shows a sea of pillars with islands of densely packed pillars, which eventually evolve to fully formed dendrites. The development of the dendrites depends on the Cs fluence and temperature. Analysis of the sputtered surface by physicochemical methods shows that the mechanism responsible for the formation of the observed microstructures is reactive ion sputtering. It originates from the chemical reaction between the target material and primary projectile and is combined with mass transport induced by ion sputtering. The importance of chemical reaction for the formation of the described structures is shown directly by comparing the change in the surface morphology under the same dose of a nonreactive 1 keV xenon ion beam.

Benefits emerging from applying high-entropy ceramics in Li-ion technology are already well-documented in a growing number of papers. However, an intriguing question may be formulated: how can the multicomponent solid solution-type material ensure stable electrochemical performance? Utilizing an example of nonequimolar Sn-based Sn0.8(Co0.2Mg0.2Mn0.2Ni0.2Zn0.2)2.2O4high-entropy spinel oxide, we provide a comprehensive model explaining the observed very good cyclability. The material exhibits a high specific capacity above 600 mAh g–1under a specific current of 50 mA g–1and excellent capacity retention near 100% after 500 cycles under 200 mA g–1. The stability originates from the conversion-alloying reversible reactivity of the amorphous matrix, which forms during the first lithiation from the initial high-entropy structure, and preserves the high level of cation disorder at the atomic scale. In the altered Li-storage mechanism in relation to the simple oxides, the unwanted aggregated metallic grains are not exsolved from the anode and therefore do not form highly lithiated phases characterized by large volumetric changes. Also, the electrochemical activity of Mg from the oxide matrix can be clearly observed. Because the studied compound was prepared by a conventional solid-state route, implementation of the presented approach is facile and appears usable for any oxide anode material containing a high-entropy mixture of elements.

Thermal energy storage is a promising, sustainable solution for challenging energy management issues. We deploy the fabrication of the reduced graphene oxide (rGO)–polycarbonate (PC) as shell and polyethylene glycol (PEG) as core to obtain hydrophobic phase change electrospun core–shell fiber system for low-temperature thermal management application. The encapsulation ratio of PEG is controlled by controlling the core flow rate, and ~ 93% heat energy storage efficacy is apparent for 1.5 mlh−1of core flow rate. Moreover, the prepared fiber possesses maximum latent melting and freezing enthalpy of 30.1 ± 3.7 and 25.6 ± 4.0 Jg−1, respectively. The transient dynamic temperature vs. time curve of the rGO-loaded phase change fiber demonstrates the delay of fiber surface temperature change compared to pristine fiber. We indeed show that the tunable heat transfer and thermal energy storage efficacy of phase change fiber is achieved via controlled liquid PEG delivery and the addition of rGO in shell architecture. Notably, the effectiveness of unique phase change material (PCM)–based core–shell fibers is concluded from advanced scanning thermal microscopy (SThM) and self-thermoregulation tests.

The phenomenon of superior biological behavior observed in titanium processed by an unconventional severe plastic deformation method, that is, hydrostatic extrusion, has been described within the present study. In doing so, specimens varying significantly in the crystallographic orientation of grains, yet exhibiting comparable grain refinement, were meticulously investigated. The aim was to find the clear origin of enhanced biocompatibility of titanium-based materials, having microstructures scaled down to the submicron range. Texture, microstructure, and surface characteristics, that is, wettability, roughness, and chemical composition, were examined as well as protein adsorption tests and cell response studies were carried out. It has been concluded that, irrespective of surface properties and mean grain size, the (101̅0) crystallographic plane favors endothelial cell attachment on the surface of the severely deformed titanium. Interestingly, an enhanced albumin, fibronectin, and serum adsorption as well as clearly directional growth of the cells with preferentially oriented cell nuclei have been observed on the surfaces having (0001) planes exposed predominantly. Overall, the biological response of titanium fabricated by severe plastic deformation techniques is derived from the synergistic effect of surface irregularities, being the effect of refined microstructures, surface chemistry, and crystallographic orientation of grains rather than grain refinement itself.

Water is the basis of life in the world. Unfortunately, resources are shrinking at an alarming rate. The lack of access to water is still the biggest problem in the modern world. The key to solving it is to find new unconventional ways to obtain water from alternative sources. Fog collectors are becoming an increasingly important way of water harvesting as there are places in the world where fog is the only source of water. Our aim is to apply electrospun fiber technology, due to its high surface area, to increase fog collection efficiency. Therefore, composites consisting of hydrophobic and hydrophilic fibers were successfully fabricated using a two-nozzle electrospinning setup. This design enables the realization of optimal meshes for harvesting water from fog. In our studies we focused on combining hydrophobic polystyrene (PS) and hydrophilic polyamide 6 (PA6), surface properties in the produced meshes, without any chemical modifications, on the basis of new hierarchical composites for collecting water. This combination of hydrophobic and hydrophilic materials causes water to condense on the hydrophobic microfibers and to run down on the hydrophilic nanofibers. By adjusting the fraction of PA6 nanofibers, we were able to tune the mechanical properties of PS meshes and importantly increase the efficiency in collecting water. We combined a few characterization methods together with novel image processing protocols for the analysis of fiber fractions in the constructed meshes. The obtained results show a new single-step method to produce meshes with enhanced mechanical properties and water collecting abilities that can be applied in existing fog water collectors. This is a new promising design for fog collectors with nano- and macrofibers which are able to efficiently harvest water, showing great application in comparison to commercially available standard meshes.

Piezoelectric polymers are promising energy materials for wearable and implantable applications for replacing bulky batteries in small and flexible electronics. Therefore, many research studies are focused on understanding the behavior of polymers at a molecular level and designing new polymer-based generators using polyvinylidene fluoride (PVDF). In this work, we investigated the influence of voltage polarity and ambient relative humidity in electrospinning of PVDF for energy-harvesting applications. A multitechnique approach combining microscopy and spectroscopy was used to study the content of the β-phase and piezoelectric properties of PVDF fibers. We shed new light on β-phase crystallization in electrospun PVDF and showed the enhanced piezoelectric response of the PVDF fiber-based generator produced with the negative voltage polarity at a relative humidity of 60%. Above all, we proved that not only crystallinity but also surface chemistry is crucial for improving piezoelectric performance in PVDF fibers. Controlling relative humidity and voltage polarity increased the d33piezoelectric coefficient for PVDF fibers by more than three times and allowed us to generate a power density of 0.6 μW·cm–2from PVDF membranes. This study showed that the electrospinning technique can be used as a single-step process for obtaining a vast spectrum of PVDF fibers exhibiting different physicochemical properties with β-phase crystallinity reaching up to 74%. The humidity and voltage polarity are critical factors in respect of chemistry of the material on piezoelectricity of PVDF fibers, which establishes a novel route to engineer materials for energy-harvesting and sensing applications.

Ni–Cu alloys are a suitable candidate as a catalyst in Hydrogen Evolution Reaction due to their catalytic performance and good stability. To enhance this activity more, the active surface area of the material should be enhanced. It is commonly achieved by the synthesis of metals and alloys in the form of nanostructures. In this work, Ni cones fabricated by the one-step method were applied as a substrate for the deposition of thin Cu layers. Then, these materials were annealed in an ambient atmosphere to obtain Ni–Cu structures. The investigation of changes in morphology and chemical composition, as well as roughness and wettability before and after the annealing process was performed. Moreover, the measurements of catalytic properties were carried out in 1 M NaOH. The values of the Tafel slope and the electrochemical active surface area were studied. The proposed method can be successfully applied to fabricate structures of other alloys for the desired properties.

Triboelectric generators rely on contact-generated surface charge transfer between materials with different electron affinities to convert mechanical energy into useful electricity. The ability to modify the surface chemistry of polymeric materials can therefore lead to significant enhancement of the triboelectric performance. Poly(methyl methacrylate) (PMMA) is a biocompatible polymer commonly used in medical applications, but its central position on the triboelectric series, which empirically ranks materials according to their electron-donating or electron accepting tendencies, renders it unsuitable for application in triboelectric generators. Here, we show that the surface potential of PMMA fibers produced by electrospinning can be tailored through the polarity of the voltage used during the fabrication process, thereby improving its triboelectric performance, as compared to typically spin-coated PMMA films. The change in surface chemistry of the electrospun PMMA fibers is verified using X-ray photoelectron spectroscopy, and this is directly correlated to the changes in surface potential observed by Kelvin probe force microscopy. We demonstrate the enhancement of triboelectric energy harvesting capability of the electrospun PMMA fibers, suggesting that this surface potential modification approach can be more widely applied to other materials as well, for improved triboelectric performance.

This study represents the unique analysis of the electrospun scaffolds with the controlled and stable surface potential without any additional biochemical modifications for bone tissue regeneration. We controlled surface potential of polyvinylidene fluoride (PVDF) fibers with applied positive and negative voltage polarities during electrospinning, to obtain two types of scaffolds PVDF(+) and, PVDF(−). The cells’ attachments to PVDF scaffolds were imaged in great details with advanced scanning electron microscopy (SEM) and 3D tomography based on focus ion beam (FIB-SEM). We presented the distinct variations in cells shapes and in filopodia and lamellipodia formation according to the surface potential of PVDF fibers that was verified with Kelvin probe force microscopy (KPFM). Notable, cells usually reach their maximum spread area through increased proliferation, suggesting the stronger adhesion, which was indeed double for PVDF(−) scaffolds having surface potential of −95 mV. Moreover, by tuning the surface potential of PVDF fibers, we were able to enhance collagen mineralization for possible use in bone regeneration. The scaffolds built of PVDF(−) fibers demonstrated the greater potential for bone regeneration than PVDF(+), showing after 7 days in osteoblasts culture produce well-mineralized osteoid required for bone nodules. The collagen mineralization was confirmed with energy dispersive X-ray spectroscopy (EDX) and Sirius Red staining, additionally the cells proliferation with fluorescence microscopy and Alamar Blue assays. The scaffolds made of PVDF fibers with the similar surface potential to the cell membranes promoting bone growth for next-generation tissue scaffolds, which are on a high demand in bone regenerative medicine.

Here, we present a one-step synthesis method of nickel–ruthenium materials, based on electrodeposition from an ethylene glycol-choline chloride (ethaline)-based bath containing inorganic additives. The electrochemical codeposition of Ni and Ru was carried out onto carbon fiber paper (CFP) under constant potentials. The morphology and composition of the obtained materials have been examined by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It has been revealed that depending on deposition conditions, either branch-like or porous, mostly amorphous structures are formed on the CFP support. Selected Ni–Ru materials were subjected to thermal selenization, and their electrocatalytic properties toward the hydrogen evolution reaction were evaluated in both 0.5 M H2SO4and 1.0 M KOH solutions. The experimental results demonstrated a notable enhancement in activity compared to that of Ni–Se materials. Moreover, the NiRuSe materials exhibited good stability over 100 h of continuous electrocatalysis, indicating their large potential as durable electrocatalysts for hydrogen production.

The nucleation of bubbles on solid surfaces is an important phenomenon in nature and technological processes like electrolysis. During proton-exchange membrane electrolysis, the nucleation and separation of the electrically nonconductive oxygen in the anodic cycle plays a crucial role to minimize the overpotential it causes in the system. This increases the efficiency of the process, making renewable energy sources and the “power-to-gas” strategy more viable. A promising approach is to optimize gas separation by surface functionalization in order to apply a more advantageous interface to industrial materials. In this work, the connection between the wettability and bubble nucleation of oxygen is investigated. For tailoring the wettability of Ti64 substrates, the direct laser interference patterning method is applied. A laser source with a wavelength of 1064 nm and a pulse duration of 12 ps is used to generate periodic pillar-like structures with different depths up to ∼5 μm. The resulting surface properties are characterized by water contact angle measurement, scanning electron microscopy, confocal microscopy, and X-ray photon spectroscopy. It was possible to generate structures with a water contact angle ranging from 20° up to nearly superhydrophobic conditions. The different wettabilities are validated based on X-ray photon spectroscopy and the different elemental composition of the samples. The results indicate that the surface character of the substrate adapts depending on the surrounding media and needs more time to reach a steady state for deeper structures. A custom setup is used to expose the functionalized surfaces to oxygen-oversaturated solutions. It is shown that a higher hydrophobicity of the structured surface yields a stronger interaction with the dissolved gas. This significantly enhances the oxygen nucleation up to nearly 350% by generating approximately 20 times more nucleation spots, but also smaller bubble sizes and a reduced detachment rate.

The novel polymeric coatings of oligoperoxide-graft-poly(4-vinylpyridine-co-oligo(ethylene glycol)ethyl ether methacrylate246) [oligoperoxide-graft-P(4VP-co-OEGMA246)] attached to glass were successfully fabricated. The composition, thickness, morphology, and wettability of resulting coatings were analyzed using X-ray photoelectron spectroscopy, ellipsometry, atomic force microscopy, and contact angle measurements, respectively. In addition, adsorption of the bovine serum albumin was examined with fluorescence microscopy. The thermal response of wettability and morphology of the coatings followed by that of protein adsorption revealed two distinct transitions at 10 and 23 °C. For the first time, three stage switching was observed not only for surface wetting but also for morphology and protein adsorption. Moreover, the influence of the pH on thermo-sensitivity of modified surfaces was shown.

Drinking water treatment produces groundwater treatment residuals (GWTRs), which can be used as mineral sorbents. GWTRs, sometimes referred to as water treatment sludge or waterworks sludge, are by-products produced by drinking water treatment plants. Their disposal is problematic and costly due to environmental constraints and has provided the impetus for research into their reuse as mineral sorbents. The main constituents of the sludge are iron and manganese oxyhydroxides, with calcium carbonate and detrital quartz (Q) in minor amounts. In this study, we investigated the sorption capacity of GWTRs toward Cd(II), Cu(II), Pb(II), Zn(II), and Cr(III), determining the effects of contact time, temperature, initial metal concentration, and pH on metal sorption efficiency. GTWRs are very effective metal sorbents, sorbing from tens to up to 230g of metal/kg of sorbent, depending on the metal. Optimal conditions for sorption are pH 5-8, a reaction time of 4-5hours, and temperature 298K. Investigations of the material after sorption by X-ray diffraction (XRD), infrared spectroscopy (FTIR), photoelectron spectroscopy (XPS), scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) have provided insight into the nature of the interaction of metals with GWTRs and described the reaction mechanism. Metals are removed from the solution through the processes of inner-sphere adsorption on the surface of the precipitate, coprecipitation with iron compounds and incorporation into the ferrihydrite (Fh) structure or precipitation in the form of their mineral phases, such as carbonates, metal oxides or hydroxides. The results obtained from the experiments show that GWTRs effectively remove metal cations from aqueous solutions and can be used as sorbents for pollutants from wastewater or liquid industrial waste. The next step should be to test the ability against anionic forms of metals and organic compounds.

Zeolite X derived from fly ash was modified with Cu(NO3)2∙3 H2O solutions of various initial concentrations (0.01, 0.05, 0.10, 0.15, and 0.20 M). The obtained materials were investigated by means of XRD, XRF, N2adsorption-desorption, and pHpzc. The concentration of Cu(NO3)2∙3 H2O significantly affected both the textural and chemical surface properties of the obtained zeolites. The materials were subjected to a series of adsorption experiments to remove phosphate ions from aqueous solutions. The highest adsorption capacity was obtained for zeolite X modified with 0.05 M Cu(NO3)2∙3 H2O solution, and the obtained adsorption capacity was 87.7 mg (PO43-) g−1. The adsorption mechanism was investigated by means of XPS analysis and correlated with the assumptions of kinetic adsorption models. The interaction between phosphate ions and Cu species on the zeolite surface was found to be the guiding mechanism of adsorption. Additional mechanisms, including precipitation as calcium phosphate and electrostatic attraction, should also be taken into account. A single-point adsorption of phosphate ions was also studied to evaluate the effects of adsorbent dose (1, 2, and 3 g L−1) and adsorption temperature (18, 25 and 40 °C). Increased adsorbent dose resulted in a significantly greater removal of phosphate ions for zeolite Cu0.05X (up to 65.4%). The temperature of 25 °C was found to be the most suitable for conducting adsorption of phosphate ions. Leaching test was performed in water to investigate the risk of applying the investigated zeolites in aqueous solutions as potential adsorbents.

In this work, the conical Co–Fe alloy structures were synthesized by two different methods: a two- and a one-step. The synthesis of nanoconical structures with regular, well-defined geometrical features, called the two-step method, requires using porous Anodic Alumina Oxide (AAO) templates. Contrary, any advanced pre-preparation of the substrate is not necessary for the one-step method. The fabrication of cones is carried out from the electrolyte containing an addition of a crystal modifier. Co and Fe are applied as electrodes in an alkaline environment. Their catalytic performance can be enhanced by modification of the shape and size of their structures, and in consequence, developing their active surface area. Many methods were used to analyze the coatings, such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDS), Energy-Dispersive X-ray Spectrometry (EDAX), X-ray Photoelectron Spectroscopy (XPS), and X-ray diffraction analysis (XRD). The catalytic properties of the coatings were recorded during the hydrogen evolution reaction and the reduction of the hydrogen peroxide and compared with the catalytic activity of bulk alloy. Nanocones produced in AAO templates were characterized by significantly higher catalytic activity and sensitivity in both reactions. However, they were unstable in the time of the experiment duration. Cones synthesized by the one-step method can be successfully applied as a catalyst and H2O2detector.

The addition of crystal modifier to electrolyte used during electrodeposition of metals and alloys allows obtaining conical structures without using any template. This method is fast and ensures covering large areas during one single electrodeposition process. In this work, Co–Fe cones were obtained by one-step method with ammonium chloride as a crystal modifier. The influence of electrodeposition parameters and electrolyte compositions were investigated. Electrodeposition conditions (duration, electrolyte temperature, and addition of NH4Cl), which allow obtaining the most uniform conical structures, were applied during sample fabrication in the magnetic field. The influence of its value and direction on the quality and compositions of obtained alloys was investigated using Scanning Electron Microscope (SEM) photos. To check if there is any change in the sample crystal system, the X-Ray Diffraction (XRD) analysis was performed. To confirm the synthesis of Co–Fe cones, they were analyzed using the X-ray photoelectron Spectroscopy (XPS) method.

Access to clean water is a global challenge, and fog collectors are a promising solution. Polycarbonate (PC) fibers have been used in fog collectors but with limited efficiency. In this study, we show that controlling voltage polarity and humidity during the electrospinning of PC fibers improves their surface properties for water collection capability. We experimentally measured the effect of both the surface morphology and the chemistry of PC fiber on their surface potential and mechanical properties in relation to the water collection efficiency from fog. PC fibers produced at high humidity and with negative voltage polarity show a superior water collection rate combined with the highest tensile strength. We proved that electric potential on surface and morphology are crucial, as often designed by nature, for enhancing the water collection capabilities viathe single-step production of fibers without any postprocessing needs.