High Surface Potential Research Articles

Boosting spontaneous orientation polarization of polar molecules based on fluoroalkyl and phthalimide units

Polar organic molecules form spontaneous polarization in vacuum-deposited films by permanent dipole orientations in the films, originating from the molecule’s potential ability to align itself on the film surface during deposition. This study focuses on developing polar molecules that exhibit spontaneous orientation polarization (SOP) and possess a high surface potential. In the proposed molecular design, a hexafluoropropane (6F) unit facilitates spontaneous molecular orientation to align the permanent dipoles, and a phthalimide unit induces strong molecular polarization. Furthermore, the introduction of phthalimides into the molecular backbone raises the glass transition temperature of the molecules, leading to the suppression of molecular mobility on the film surface during film deposition and an improvement in the dipole orientation. The resulting surface potential slope is approximately 280 mV nm−1 without substrate temperature control. Furthermore, this work proposes a method using position isomers as a design strategy to tune the SOP polarity. The substitution position of the strong polar units influences the direction of the total molecular dipoles and affects the SOP polarity of the 6F-based molecules. The proposed molecular designs in this study provide wide tunability of the SOP intensity and polarity, which contributes to highly efficient organic optoelectronic and energy-harvesting devices.

(Not) in my city: An explorative study on social acceptance of photovoltaic installations on buildings

Existing buildings provide high surface potential for photovoltaic (PV) installations. When deciding whether a building is suitable for solar energy harvesting, social acceptance needs to be considered. While PV is accepted in general, research regarding the acceptance of PV for specific types of buildings is sparse. In two explorative studies, we investigated the building-specific acceptance of PV installations, taking new PV module designs into account.The aim of the first study (N = 76, passersby in the Botanical Garden, Freiburg i. Br. Germany who volunteered to participate) was to investigate which PV module designs are accepted for different buildings. Six different PV crystalline silicon module prototypes varying in color and surface structure were presented on an exhibition table. Using a paper-pencil-survey, participants rated the modules and combined them with presented buildings. Results show that depending on the building, different modules were favored whereby PV modules were chosen mostly due to color integration.In a second study (N = 109, recruited from the participant pool of the institute of psychology, University of Freiburg, Germany, mostly students, and in social media), participants indicated their acceptance of a PV installation for 24 different buildings in an online survey. Results revealed that social acceptance for PV installations on buildings was generally high and was even higher if the PV module was aesthetically integrated or invisibly. PV modules on historical buildings (including a church) were less accepted than on modern buildings. Yet for invisible PV modules, there were no acceptance differences between buildings. Building variables were found to be more important to predict building-specific acceptance than person-related variables such as environmental concerns, values or political attitude.Taken together, the study gives a first insight into the subject of the social acceptance of urban PV installations. Results underline the importance of aesthetic integration and (in)visibility for PV installation on buildings.

Enhancing electricity generation from water evaporation through cellulose-based multiscale fibers network

Harvesting energy from the water − solid interface through natural water evaporation provides a promising approach for generating sustainable electricity to power self-powered electronics. Advancing the bio-based hydrovoltaic materials enhances sustainability, with wood as a viable candidate due to the inherent hydrophilic and charged properties. However, current wood-based water evaporation-induced electricity generators (WEIGs) mainly depend on the “top-down” construction strategies. Wherein, the improvement of power density is constrained by the limited structural regulation, nondiverse building blocks, and monolithic enhancement mechanisms. Here, the high-performance wood-based WEIGs based on multiscale fibers network (MFN) are reported by embedding the Ti4O7 nanofibers (T4NF) inside the assemblies of TEMPO-oxidized cellulose nanofibrils (TOCNF) through a “bottom-up” route. Benefiting from the large specific surface area, high surface potential, and photothermal effect of conductive T4NF, the WEIG achieves a high short-circuit current of ∼13.7 μA while delivering ∼0.94 V open-circuit voltage. This work presents an efficient method to boost performance while understanding the impact of functional MFN on water evaporation.

Influence of inorganic solid particles on the stability of water-in-crude oil emulsions: Evaluating the role of surface charge

This study examines the effect of inorganic solid particles on the stability of water-in-oil (W/O) emulsions formed during the transportation, refining, and storage of crude oil. The surface properties of inorganic particles, such as kaolinite and calcite, can influence the interface between crude oil and water, affecting the stability of the emulsion. The study evaluates the quantitative effect of these particles on emulsion stability and investigates how surface properties affect the emulsions. Emulsions were prepared using crude oil and synthetic brine, with calcite and kaolinite added as inorganic solid particles. Adding inorganic solids increased the volume of released water and altered the emulsion stability, with high concentrations decreasing the formation of stable emulsions. The dissolution of inorganic solids increased the pH of the solution and promoted demulsification due to the high surface potential of crude oil. The solid particles enhanced the formation of oil-in-water-in-oil (O/W/O) emulsions, generating unstable emulsions. The study also found that increasing temperature and adding inorganic solids decreased the emulsion height over time, which was predicted by the emulsion layer growth model. The coagulation rate constant was a tuning parameter, with a higher value implying higher internal repulsion and stronger coagulation between water droplets, facilitating emulsion instability. It has been observed that elevating the storage temperature and introducing kaolinite accelerates the coagulation rate constant, whereas the addition of calcite decreases this value, ultimately contributing to the stabilisation of the emulsions.

A super-hydrophilic graphite directly from lignin enabled by a room-temperature cascade catalytic carbonization

A cost-effective, and low-energy room-temperature cascade catalytic carbonization strategy is demonstrated for converting lignin into graphite with a high yield of 87 %, a high surface potential of −37 eV and super-hydrophilicity. This super-hydrophilic feature endows the lignin-derived graphite to be dispersed in a variety of polar solvents, which is important for its future applications. Encapsulating of liquid metals with the graphite for electrical circuit patterning on flexible substrates is also advocated. These written patterns show superb conductivity of 4.9 × 106 S/m, offering good performance stability and reliability while being repeatedly stretched, folded, twisted, and bent. This will offer new designs for flexible electronic devices, sensors, and biomedical devices.

A Novel Mechano-Synthesized Zeolitic Tetrazolate Framework for a High-Performance Triboelectric Nanogenerator and Self-Powered Selective Neurochemical Detection.

Designing a high-performing triboelectric novel material with eco-friendly, rapid, and cost-effective synthesis is the future of material research in triboelectric nanogenerators (TENG). We report a mechanochemical ball mill synthesis of a zeolitic tetrazolate framework (ZTF-8) that is isostructural with the well-known zeolitic imidazolate framework ZIF-8. ZTF-8 is extremely stable in water, 0.1 M aqueous acid/base solutions for 75 days at 25 °C, and boiling water (100 °C) for 7 days. Kelvin probe force microscopy and molecular electrostatic surface potential computational analysis exhibited that ZTF-8 has a very high positive surface potential. Atomic force microscopy and three-dimensional digital microscopy studies reveal the high roughness profile in the ZTF-8 film. The unique structure, exceptional acid/base stability, good dielectric property, and high roughness profile combined with the extremely electropositive nature of ZTF-8 make it a suitable candidate as a polymer-free triboelectric positive material in TENG with outstanding performance (power density of 720 mW/m2). High triboelectric output was further validated using the COMSOL Multiphysics simulation tool. Simple mechanical hand tapping of the ZTF-based TENG (ZTF-TENG) device generates high electric output, which was practically used to power numerous low-powered devices like tally counter, clinical thermometer, and digital clock and also illuminates 125 light-emitting diodes. In addition, the efficiency of ZTF-TENG was utilized as a self-powered device for a selective dopamine (DA) sensor with good sensitivity (377.76 mV/μM/cm2), wide range linearity (5-120 μM), and excellent limit of detection (0.42 μM).

Possibility of inverse sheath in the lunar nightside due to secondary electron emission

This study assesses the plasma sheath formation on the night side of the Moon when exposed to highly energetic ambient plasma. The calculations indicate that the secondary electron emission (SEE) due to highly energetic plasma electrons leads to the formation of the inverse sheath around the positively charged lunar surface on the night side, where a traditional Debye sheath with a high negative surface potential is anticipated. Analytical formulation of Debye sheath and inverse sheath formation is given considering Maxwellian plasma and secondary electrons and cold ions. For a given SEE yield, a temperature regime is predicted where the inverse sheath is possible.

Effective removal of Cr (VI) from an aqueous solution using a carbon coated NiFe2O4 nano-adsorbent

Exploration of cubic ferrites for chromium removal is ongoing. Ferrites offer a promising avenue for chromium removal because of their unique properties, high surface area, magnetic recoverability, and potential for surface modifications to enhance adsorption capacities. Herein, the work highlights the synthesis of carbonaceous nickel ferrite (NiFe2O4/C) through an inert ambient pyrolysis process, where metal acetylacetonates are used as the sources of metal ions and carbon. The synthesized NiFe2O4/C was successfully characterized for its structure and morphology using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray analysis (EDX), Raman spectroscopy, Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. The study confirmed that, the size of nanostructure was of ∼29 nm, with a surface area of 56.925 m2/g, pore volume of 0.085 cc/g with type IV hysteresis loop. The regular spherical shape was observed through FESEM, and a carbon coating was evident and confirmed from TEM. Synthesized NiFe2O4/C was efficiently used for the Cr (VI) removal, it was found that at an equilibrium time of 60 min, nearly 85% of the chromium was removed using 0.01 g of adsorbent at native pH and efficiency was further improved by lowering the pH. The investigation further examined the isotherm and kinetics models. The material was regenerated for 5 cycles with a removal percentage of 57%.

Biomass-based renewable, eco-friendly nanofiber membrane: Large-scale fabrication and application in PM0.3 capture and oily wastewater purification

Biomass-based poly (trimethylene 2,5-furandicarboxylate) (PTF) was synthesized by the simple and low-cost direct esterification method. The high number-average molecular weight (Mn) of about 39.6 kDa was achieved for PTF with a polydispersity index (PDI) of 2.0, which was suitable for spinning. The electrospun PTF nanofiber membranes were fabricated firstly and displayed adjustable diameters, excellent mechanical properties (lifting 550 g weight, foldability) and large-scale preparation potential (area of 100 cm × 50 cm). More impressively, high initial surface potential (13.5 kV) was found for the electrospun in-suit electret membranes, which facilitated the capture of ultrafine PM particles. Subsequently, the PTF membrane showed exceptional particle capture capability with a filtration performance of 99.96 %, low pressure drops of 78 Pa, and a satisfactory quality factor of 0.1 Pa−1. PTF filters also demonstrated long-term service capability for purifying high PM2.5 concentration smoke (15 cycles, 55 min), and could be flexibly introduced into various practical scenarios. Additionally, based on the selective oil/water wettability of PTF membranes, which showed outstanding separation effects of oily wastewater(＞99.88 %, 15 cycles). Therefore, the development and application of the PTF nanofibers provided a sustainable alternative for separation/purification and various fields in the future.

MOFs and MOF-Based Composites as Next-Generation Materials for Wound Healing and Dressings.

In recent years, there has been growing interest in developing innovative materials and therapeutic strategies to enhance wound healing outcomes, especially for chronic wounds and antimicrobial resistance. Metal-organic frameworks (MOFs) represent a promising class of materials for next-generation wound healing and dressings. Their high surface area, pore structures, stimuli-responsiveness, antibacterial properties, biocompatibility, and potential for combination therapies make them suitable for complex wound care challenges. MOF-based composites promote cell proliferation, angiogenesis, and matrix synthesis, acting as carriers for bioactive molecules and promoting tissue regeneration. They also have stimuli-responsivity, enabling photothermal therapies for skin cancer and infections. Herein, a critical analysis of the current state of research on MOFs and MOF-based composites for wound healing and dressings is provided, offering valuable insights into the potential applications, challenges, and future directions in this field. This literature review has targeted the multifunctionality nature of MOFs in wound-disease therapy and healing from different aspects and discussed the most recent advancements made in the field. In this context, the potential reader will find how the MOFs contributed to this field to yield more effective, functional, and innovative dressings and how they lead to the next generation of biomaterials for skin therapy and regeneration.

Metal‐organic framework‐based nanofibrous film for two different modes of triboelectric nanogenerators

AbstractMetal‐organic frameworks (MOFs) are nanomaterials with engineered chemical structures, offering remarkable properties. However, their limited film‐formation capability hinders their integration into triboelectric nanogenerators (TENGs). This study proposes a simple yet effective solution to overcome this challenge by employing electrospinning techniques to integrate the zeolitic imidazolate framework (ZIF‐8) into an easy‐to‐use nanofibrous mat. ZIF‐8 has high surface potential, a unique cubical structure, and an easy fabrication process that makes it an ideal material for TENGs. By incorporating ZIF‐8 into the electrospinning solution, significant improvements are achieved in the electropositivity of the resulting nanofibers. It leads to notable changes in the shape, morphology, and roughness of electrospun fibers, consequently enhancing the overall performance of the TENG. The results indicate that utilizing the ZIF‐based electrospun mat as a tribo‐positive material can increase transferred charges between electrodes by more than 100%. Utilizing the MOF‐based nanofibrous mat, this study also introduces a novel rotary TENG that works based on a mode of TENG operation called rolling mode. The reliable charge generation by the proposed rolling system reveals that this mode of TENG operation could be a superb alternative for traditional TENG modes, like contact/separation or sliding, which cause high levels of mechanical stress due to harsh physical impact or friction.

Branched polymer grafted loose nanofiltration membrane with high surface potential for dye desalination

Herein, a thin and high-potential loose nanofiltration (LNF) membrane was fabricated by one-step cross-linking with branched polyethyleneimine (PEI) using the reactive sites on the styrene maleic anhydride/chlorinated polyvinyl chloride membrane surface to for alkylation and nucleophilic addition reactions, respectively. As the molecular weight of branched PEI increased, the thickness of LNF membranes decreased and their pore sizes and surface potential increased (i. e., potential value of LNF membrane above 59 mV at pH = 7). Density functional theory calculations were used to understand the separation mechanism of LNF membranes. The rejection mechanisms of these membranes for Brilliant Blue R250, Methyl blue, Congo red, and Acid fuchsin were based on size-sieving, with rejection for all >95 %. However, the rejection mechanisms of Bromocresol green and Bromothymol blue were affected by the size-electrostatic synergy. Pleasingly, the NaCl rejection was <10 %. Furthermore, the 22 k-PEI-modified LNF membrane could not only effectively separate dye/NaCl under high pressure and high salinity but also maintain long-term stable desalination performance. Notably, the assessment of dye rejection in LNF membranes revealed that it is not solely based on the molecular weight of dye but is also related to the geometric shape of the organic substance.

Adjustable Plane Curvature of Covalent Organic Framework Enabling Outstanding Dielectric, Electret, and High‐Temperature Processing Properties

AbstractWith the rapid development of integrated circuits towards miniaturization and complexity, there is an urgent need for materials with low dielectric constant/loss and high processing temperatures to effectively prevent signal delay and crosstalk. With high porosity, thermal stability, and easy structural modulation, covalent organic frameworks have great potential in the field of low dielectric materials. However, the optimization of dielectric properties by modulating the conjugated/plane curvature structure of covalent organic frameworks (COFs) has rarely been reported. Accordingly, we herein innovatively prepare COF films with adjustable planar curvature, hence possessing ultralow dielectric constant (1.9 at 1 kHz), ultralow dielectric loss at 1 kHz (0.0029 at room temperature, 0.0052 at 200 °C), high thermal decomposition temperature (5 % weight loss temperature, 473 °C) and good hydrophobicity (water contact angle, 105.3°). Also, to the best of our knowledge, we are the first to report that the resulting COF film enables high surface potential (≈320 V) for one week, attributing to its intrinsic high porosity, thus presenting great potential in electret applications. Accordingly, this innovative work provides a readily available and scalable idea to prepare materials with comprehensively excellent dielectric and electret properties as well as high processing temperatures simultaneously for advanced electronic device applications.

Structure and surface properties of ozone-conjugated octenyl succinic anhydride modified waxy rice starch: Towards high-stable Pickering emulsion

In the present work, a dual-modified waxy rice starch (OOWRS) fabricated with OSA and ozone was successfully used to stabilize the O/W Pickering emulsion. The molecular structure, surface properties, and underlying stabilizing mechanism were systematically investigated. The results showed that oxidation occurring on the surface of OSA-modified waxy rice starch (OSAWRS) resulted in the presence of indentations and cracks. The relative crystallinity of starch was generally decreased with increasing degree of oxidation. Due to the introduction of carbonyl and the variation in surface structure, the hydrophobicity and acidity of OSAWRS were significantly enhanced after the ozone treatment. Remarkably, OOWRS stabilized Pickering emulsion exhibited a feature of typical O/W emulsion, and the 0.5 h and 1 h OOWRS emulsion exhibited a more uniform droplet size as well as a higher surface potential. We also noted that a weak-gel network was formed within the OOWRS emulsion system as the hydrophilic starch chains played a bridging role. Two reasons for the improved stability of the emulsion were the special gel structure and the enhanced electrical repulsion among the droplets. This research provides that ozone-conjugated OSA modification is a promising strategy for improving the emulsion ability of starch-based Pickering emulsions.

Two-dimensional manganese di-telluride based triboelectric nanogenerator

Low-dimensional transition metal chalcogenides (TMDCs) have gained interest as potential energy harvesters. The structural change during dimensional reduction paves the way for better charge repositories compared to their bulk counterparts. Thin flakes of manganese di-telluride (MnTe2) were used to devise a triboelectric nanogenerator (TENG), and the device was capable of producing a maximum power density of 123 mW cm-2, with a sensitivity of ∼ 408 mV kPa-1. The device also has a high surface potential of 1.02 V and surface charge density (SCD) of 2.204 mC m-2, respectively. The effect of uniaxial and biaxial strains on the two-dimensional (2D) TENG was studied using in-situ Raman spectroscopy. The enhanced outputs in the 2D device were attributed to the Te - di vacancies created during exfoliation in the flakes (DFT calculations). The potential application of the fabricated device is to be used as an energy harvester from air-conditioning (AC) ducts.

Hydrovoltaic Effect Coupling with Capacitor Amplification: A Mode for Sensitive Self-Powered Electrochemical Sensing.

Self-powered electrochemical sensors, which can function without external electricity, are incredibly valuable in the realm of sensing. However, most of the present testing methods are normally confined to high environmental requirements, restricted lighting conditions, and temperature differences. Herein, an innovative self-powered electrochemical sensor was successfully developed based on hydrovoltaic effect coupling with capacitor amplification. Due to the combined merits from the two-dimensional transition metal carbides and nitrides (MXene)-polyaniline (PANI) with high surface potential and good hydrophilicity, and the capacitor amplification strategy, the device could harvest electric energy from water evaporation and displayed a high short circuit current value. Under optimal conditions, the proposed self-powered electrochemical sensor presented excellent sensitivity and high specificity for enrofloxacin (ENR) detection in the concentration range from 1 fM to 1 nM with a detection limit of 0.585 fM. Such a proposed sensor also has the advantages of environmental friendliness and ease of use, which is an ideal choice for accurately and precisely detecting ENR in real samples. The mode of such electrochemical detection outlined in this technical note implements a breakthrough in designing self-powered electrochemical sensors, providing a rational basis for development of a diversified sensing platform.

Regulation of TiO2 @PVDF piezoelectric nanofiber membranes on osteogenic differentiation of mesenchymal stem cells

Bioactive piezoelectric materials with similar properties as natural bone tissue with piezoelectricity have been explored for bone repair. Polyvinylidene fluoride (PVDF) is among the most studied piezoelectric polymers and has been manifested to promote osteogenic differentiation. Unfortunately, in the practical application of bone repair, bioactive materials as implants have faced poor electrical signal stability and poor modulation of bone regeneration, which have seriously hindered their further development. Here, we fabricated a composite piezoelectric fibrous membrane with titanium dioxide (TiO2) nanoparticles and PVDF (TiO2 @PVDF) for cellular osteogenic differentiation. The expression quantity of the gene osteocalcin (OCN) with the piezoelectric fibrous membrane was 49 times and 6 times higher than the expression quantity of OCN with the control group and with the pure polyvinylidene fluoride (PVDF), respectively. Moreover, the membrane with 0.3 wt% TiO2 (P-0.3TN) generated high surface potential and significantly promoted cell adhesion and proliferation through electromechanical stimulation early in osteogenic differentiation. Alkaline phosphatase (ALP) activity was increased up to 2-fold by stimulation of electrical and mechanical signals through piezoelectric fibers, effectively inducing osteogenic differentiation at the early stage. The proposed mechanism of regulating osteogenic differentiation behavior by the surface potential of TiO2 @PVDF piezoelectric fiber composite membrane provides guidance for designing electroactive materials to promote osteogenic differentiation and bone regeneration and remodeling.

Investigation of bovine β-lactoglobulin-procyanidin complexes interactions and its utilization in O/W emulsion

Procyanidins are bioactive polyphenols that have a strong affinity to proteins. Beta-lactoglobulin (BLG) is widely used as an emulsifier in the food and other industries. This study evaluated the interaction between BLG and A-type procyanidin dimer (PA2) using the spectroscopic, thermodynamic, and molecular simulation. PA2 decreased the transmissivity and quenched the intrinsic fluorescence of BLG, suggesting that the two molecules formed a complex. The binding of PA2 reduced the surface hydrophobicity and altered the conformation of BLG with increasing the random coil regions. Thermodynamic and isothermal titration calorimetry analyses suggested that the main driving force of PA2-BLG interaction was hydrophobic attraction. Molecular docking simulations were used to identify the main interaction sites and forces in the BLG-PA2 complexes, which again indicated that hydrophobic interactions dominated. In addition, the influence of PA2 on the ability of BLG to form and stabilize O/W emulsions was analyzed. Emulsions formulated using BLG-PA2 complexes contained relatively small droplets (D4,3 ≈ 0.7 μm) and high surface potentials (absolute value >50 mV). Compared to BLG alone, BLG-PA2 complexes improved the storage stability of the emulsions. This study provides valuable new insights into the formation, properties, and application of protein-polyphenol complexes as functional ingredients in foods.

Bioactivity Enhancement of Plasma-Sprayed Hydroxyapatite Coatings through Non-Contact Corona Electrical Charging.

Atmospheric plasma spray (APS) remains the only certified industrial process to produce hydroxyapatite (Hap) coatings on orthopaedic and dental implants intended for commercialization. Despite the established clinical success of Hap-coated implants, such as hip and knee arthroplasties, a concern is being raised regarding the failure and revision rates in younger patients, which are increasing rapidly worldwide. The lifetime risk of replacement for patients in the 50-60 age interval is about 35%, which is significantly higher than 5% for patients aged 70 or older. Improved implants targeted at younger patients are a necessity that experts have been alerted to. One approach is to enhance their bioactivity. For this purpose, the method with the most outstanding biological results is the electrical polarization of Hap, which remarkably accelerates implant osteointegration. There is, however, the technical challenge of charging the coatings. Although this is straightforward on bulk samples with planar faces, it is not easy on coatings, and there are several problems regarding the application of electrodes. To the best of our knowledge, this study demonstrates, for the first time, the electrical charging of APS Hap coatings using a non-contact, electrode-free method: corona charging. Bioactivity enhancement is observed, establishing the promising potential of corona charging in orthopedics and dental implantology. It is found that the coatings can store charge at the surface and bulk levels up to high surface potentials (>1000 V). The biological in vitro results show higher Ca2+ and P5+ intakes in charged coatings compared to non-charged coatings. Moreover, a higher osteoblastic cellular proliferation is promoted in the charged coatings, indicating the promising potential of corona-charged coatings when applied in orthopedics and dental implantology.

Electret elastomer-based stretchable triboelectric nanogenerators with autonomously managed power supplies for self-charging systems

Stretchable power sources capable of accommodating large deformations are urgently demanded for various stretchable and wearable electronics. In this work, we report a stretchable electret-based triboelectric nanogenerator (SEB-TENG) consisting of elastomeric electret as electrification materials and organo-hydrogels as electrodes. The electret elastomer, prepared by uniformly dispersing SiO2 nanoparticles in the elastomer matrix and thermally injecting static charges, obtains a high surface potential, high tensile strain (796%), and long stability. Then, the SEB-TENG device also achieves high stretchability (423%) and high charge density (0.2 mC m−2). Furthermore, a power management module (PMM) is designed to maximize the energy utilization of the SEB-TENG. The integrated self-charging system can be sufficiently used to constantly power a watch, or charge a Li-ion coin cell which subsequently provides sustainable power supplies to a digital thermometer. This work provides a viable approach to simultaneously achieve high output performances and high stretchability of integrated power sources.