Pristine Substrate Research Articles

High-performance thin-film composite forward osmosis membranes with hydrophilic PDA@TiO2 nanocomposite substrate for the treatment of oily wastewater under PRO mode

The applications of thin-film composite (TFC) forward osmosis (FO) membranes are limited by low flux and strong internal concentration polarization (ICP). In this study, a simple, facile, and eco-friendly approach to improve the wettability of the FO membrane substrate using hydroxyl- and amino-functionalized TiO2 nanocomposites by polydopamine (PDA) coating on TiO2 particles is demonstrated. In our research, a composite membrane substrate was fabricated by incorporating PDA@TiO2 into polyethersulfone (PES) through the non-solvent induced phase separation (NIPS) process. Then, a selective active polyamide layer was formed by interfacial polymerization on top of the PES-PDA@TiO2 membrane substrate to obtain the resulting TFC-FO membrane. The composite membrane substrate exhibited higher hydrophilicity (about 25% lower contact angle) and higher porosity than the pristine membrane substrate. The water flux (Jw) of 34.3 L/m2h and 60.1 L/m2h was achieved for the resulting TFC-PDA@TiO2 FO membrane under FO and pressure retarded osmosis (PRO) modes which was ~174% and ~183% higher than that of the pristine TFC-FO membrane under FO and PRO modes respectively. Furthermore, the TFC-PDA@TiO2 membrane exhibited enhanced selectivity, as expressed by the decrease in the specific salt flux (Js/JW) values (from 0.48 g/L and 0.53 g/L of pristine TFC to 0.27 g/L and 0.28 g/L for TFC-PDA@TiO2 under the FO and PRO modes respectively). More importantly, the TFC-PDA@TiO2 membrane exhibited better fouling behavior with the organic foulant solution. These results demonstrate that the fabricated TFC-FO membranes have significant potential for sustainable water reclamation from oily wastewater via FO under the PRO mode.

Bidirectional Modulation of Neuronal Cells Electrical and Mechanical Properties Through Pristine and Functionalized Graphene Substrates.

In recent years, the quest for surface modifications to promote neuronal cell interfacing and modulation has risen. This course is justified by the requirements of emerging technological and medical approaches attempting to effectively interact with central nervous system cells, as in the case of brain-machine interfaces or neuroprosthetic. In that regard, the remarkable cytocompatibility and ease of chemical functionalization characterizing surface-immobilized graphene-based nanomaterials (GBNs) make them increasingly appealing for these purposes. Here, we compared the (morpho)mechanical and functional adaptation of rat primary hippocampal neurons when interfaced with surfaces covered with pristine single-layer graphene (pSLG) and phenylacetic acid-functionalized single-layer graphene (fSLG). Our results confirmed the intrinsic ability of glass-supported single-layer graphene to boost neuronal activity highlighting, conversely, the downturn inducible by the surface insertion of phenylacetic acid moieties. fSLG-interfaced neurons showed a significant reduction in spontaneous postsynaptic currents (PSCs), coupled to reduced cell stiffness and altered focal adhesion organization compared to control samples. Overall, we have here demonstrated that graphene substrates, both pristine and functionalized, could be alternatively used to intrinsically promote or depress neuronal activity in primary hippocampal cultures.

Dye adsorptive thin-film composite membrane with magnetite decorated sulfonated graphene oxide for efficient dye/salt mixture separation

In this study, a thin-film composite (TFC) loose nanofiltration (NF) membrane comprising a poly(piperazine-amide) (PPA) active layer was successfully fabricated by the electrospray interfacial polymerization (EIP) method. Sulfonated graphene oxide (SGO) and magnetite-decorated SGO (MGO) were synthesized and individually embedded in the polymer matrix of the substrate via a phase inversion method. The hydrophilicity, surface roughness, porosity, and pure water permeance of the prepared substrates, in which the additive existed, were found to be improved in comparison with those of the pristine substrate. The MGO nanoparticle-incorporated TFC membrane (M-MGO) exhibited high permeation of salt (96.1% for NaCl) and water permeance (44.4 ± 4.0 LMH bar−1) owing to the loose structure of the active layer. The M-MGO also exhibited the highest dye rejection (Congo red, 99.0%) owing to the presence of MGO nanoparticles with an adsorption capacity. When permeating the dye and salt mixture, M-MGO achieved the highest dye/salt selectivity in comparison with those of the other membranes. Moreover, the M-MGO achieved better antifouling properties with a high flux recovery ratio (FRR) of 99.0%, whereas the pristine membrane exhibited a low FRR of 97.6% or less. This method presents a high potential for the fabrication of novel saline wastewater treatment membranes.

Embedded current collectors for efficient large area perovskite solar cells

Perovskite solar cells (PSCs) are an emerging solar cell technology that has shown the fastest growth in power conversion efficiency (PCE). The present power conversion efficiency record of 25.5% is already comparable to crystalline silicon technology, which is attracting the research and industrial community attention. The main challenges in scaling-up PSCs are the limited conductivity of the transparent electrode and the difficulty in depositing an uniform and defect-free perovskite layer over large areas. This work reports the use of engraved gold metal lines in the FTO glass substrate for increasing its electronic conductivity; the prepared 5 cm2 PSC displays a PCE enhancement of 26% over the cells prepared with pristine FTO substrates.

Constructing Mechanochemical Durable Superhydrophobic Composite Coating towards Superior Anticorrosion

AbstractCorrosion is an inevitable and thorny issue in various fields, resulting in materials degradation, environmental pollution, economic loss, and even emergency safety accidents. Owing to the special surface functions, superhydrophobic coatings are regarded as a promising strategy towards corrosion inhibition. However, the large‐scale and real‐world applications of superhydrophobic coatings are restricted by the mechanical and chemical weaknesses. Herein, a fluorine‐free dual‐layer microarc oxidation/superhydrophobic coating with mechanochemical stabilization is fabricated for corrosion protection. The dual‐layer coating maintains superhydrophobicity under ultraviolet irradiation (15 d), different pH values (1–14), different temperatures (0–100 °C) and abrasion test (180 cycles). Its impedance modulus at the lowest frequency is increased by more than six orders of magnitude than that of the pristine substrate, and the corrosion inhibition efficiency value is calculated as 99.999%. The enhancement of surface multifunctions is attributed to the synergistic effects of microarc oxidation layer and superhydrophobic layer. The as‐prepared robust dual‐layer coating with excellent properties is expected to have potential applications in material protection fields.

Single-atom catalysts with anionic metal centers: Promising electrocatalysts for the oxygen reduction reaction and beyond

Ongoing efforts to develop single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) typically focus on SACs with cationic metal centers, while SACs with anionic metal centers (anionic SACs) have been generally neglected. However, anionic SACs may offer excellent active sites for ORR, since anionic metal centers could facilitate the activation of O2 by back donating electrons to the antibonding orbitals of O2. In this work, we propose a simple guideline for designing anionic SACs: the metal centers should have larger electronegativity than the surrounding atoms in the substrate on which the metal atoms are supported. By means of density functional theory (DFT) simulations, we identified 13 anionic metal centers (Co, Ni, Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, Au, and Hg) dispersed on pristine or defective antimonene substrates as new anionic SACs, among which anionic Au and Co metal centers exhibit limiting potentials comparable to, or even better than, conventional Pt-based catalysts towards ORR. We also found that anionic Os and Re metal centers on the defective antimonene can electrochemically catalyze the nitrogen reduction reaction (NRR) with a limiting potential close to that of stepped Ru(0001). Overall, our work shows promise towards the rational design of anionic SACs and their utility for applications as electrocatalysts for ORR and other important electrochemical reactions.

Root bacteriome of a pioneer grass Miscanthus condensatus along restored vegetation on recent Miyake-jima volcanic deposits

Root-associated microorganisms play an important role in colonization and subsequent development of pioneer plants on newly exposed substrates such as volcanic deposits. However, there is still lack of an understanding how the root microbiome establishes during a short-term development without apparent soil formation when the pioneer plant colonizes on the pristine substrates. Miscanthus condensatus, the first grass to colonize recent volcanic deposits on the Island of Miyake (Miyake-jima), Japan, is a model plant suitable to address this issue. In this study, we carried out bacterial 16S rRNA gene-based real-time quantitative PCR, T-RFLP profiling and clone library analyses to assess the root bacteriome of M. condensatus from two phases of different plant-colonization, i.e., early colonizing phase (sites OY and IG7) and later dominating phase (sites IG8 and IG9). The results showed that the root-associated bacteriome had comparable 16S rRNA gene densities in the two developmental phases of colonization (4.8–11.7 × 109 and 0.1–0.6 × 109 copies g−1 sample for the rhizosphere and root-endosphere communities, respectively). The rhizosphere community changed significantly between the early and later phases, whereas this change was not as clear for the root-endosphere community. Betaproteobacteria and Gammaproteobacteria respectively occupied 11.7–29.9% and 7.1–14.2% of the rhizosphere community at the early phase and decreased to 4.8–19.1% and 3.5–5.5% of them at the later phase, while the rhizosphere compositions of Alphaproteobacteria and Actinobacteria changed from 14.8 to 16.5% and 8.9–9.0% to 16.8–22.5% and 10.4–18.1 %, respectively. According to the statistic and phylogenetic analyses, the major bacterial genera Paraburkholderia and Trinickia in the class Betaproteobacteria represented the potentially beneficial groups in the root-associated community at the early phase; however, these bacteria were subsequently displaced by the other beneficial bacteria Bradyrhizobium, Rhizobium, Agrobacterium in the class Alphaproteobacteria, and Arthrobacter and Paenarthrobacter in the class Actinobacteria with colonization by this pioneer plant. Our result suggests that bacterial succession occurs in the rhizosphere during the short-term development of pioneer plants on newly exposed volcanic deposits. Such succession partly illustrates how rhizosphere ecosystems become established during colonization and subsequent growth of pioneer plants on newly exposed substrates.

Contact transfer of engineered nanomaterials in the workplace.

This study investigates the potential spread of cadmium selenide quantum dots in laboratory environments through contact of gloves with simulated dry spills on laboratory countertops. Secondary transfer of quantum dots from the contaminated gloves to other substrates was initiated by contact of the gloves with different materials found in the laboratory. Transfer of quantum dots to these substrates was qualitatively evaluated by inspection under ultraviolet illumination. This secondary contact resulted in the delivery of quantum dots to all the evaluated substrates. The amount of quantum dots transferred was quantified by elemental analysis. The residue containing quantum dots picked up by the glove was transferred to at least seven additional sections of the pristine substrate through a series of sequential contacts. These results demonstrate the potential for contact transfer as a pathway for spreading nanomaterials throughout the workplace, and that 7-day-old dried spills are susceptible to the propagation of nanomaterials by contact transfer. As research and commercialization of engineered nanomaterials increase worldwide, it is necessary to establish safe practices to protect workers from the potential for chronic exposure to potentially hazardous materials. Similar experimental procedures to those described herein can be adopted by industries or regulatory agencies to guide the development of their nanomaterial safety programmes.

Investigating the potential of ammonium retention by graphene oxide ceramic nanofiltration membranes for the treatment of semiconductor wastewater

Ceramic membranes with high chemical and fouling resistance can play a critical role in treating industrial wastewater. In the present study, we demonstrate the fabrication of graphene oxide (GO) assembled ceramic nanofiltration (NF) membranes that provide effective ammonium retention and excellent fouling resistance for treating semiconductor wastewater. The GO-ceramic NF membranes were prepared via a layer-by-layer (LbL) assembly of GO and polyethyleneimine (PEI) on a ceramic ultrafiltration (UF) substrate. The successful fabrication of the GO-ceramic NF membranes was verified through surface characterization and pore size evaluation. We also investigated the performance of GO-ceramic NF membranes assembled with different numbers of bilayers for the rejection of ammonium ions. GO-ceramic NF membranes with three GO-PEI bilayers exhibited 8.4- and 3.2-times higher ammonium removal with simulated and real semiconductor wastewater, respectively, compared to the pristine ceramic UF substrate. We also assessed flux recovery after filtration using real semiconductor wastewater samples to validate the lower fouling potential of the GO-ceramic NF membranes. Results indicate that flux recovery increases from 39.1 % in the pristine UF substrate to 71.0 % and 90.8 % for the three- and ten-bilayers GO-ceramic NF membranes, respectively. The low-fouling GO-ceramic NF membranes developed in this study are effective and promising options for the removal of ammonium ions from semiconductor wastewater.

Manipulating Carrier Concentration by Self-Assembled Monolayers in Thermoelectric Polymer Thin Films.

Conjugated polymers have attracted considerable attention for thermoelectric applications in recent years due to their plentiful resources, diverse structures, mechanical flexibility, and low thermal conductivity. Herein, we demonstrate a new strategy of modulating charge carrier concentration of chemical-doped polymer films by modifying the substrate with self-assembled monolayers (SAMs). The SAM with a trifluoromethyl terminal group is found to accumulate holes in the polymer thin films, while the SAM with an amino terminal group tends to donate electrons to the polymer films. Thermoelectric thin films of conjugated donor-acceptor copolymer exhibit high power factors of 55.6-61.0 μW m-1 K-2 on SAMs with polar terminal groups. These power factors are 49% higher than that on the SAM with the nonpolar terminal group and 3 times higher than that on pristine substrate. The high power factor is ascribed to the modulated charge carrier concentration and improved charge carrier mobility as induced by SAMs.

Effects of 10 MeV Al4+ ions irradiation on fluorine-doped tin oxide substrates for photovoltaic device applications

The effects of 10 MeV Al4+ ions irradiation on structural, surface morphological, optical and electrical properties of fluorine-doped tin oxide (FTO) substrates are presented for solar cell applications. The ions irradiation changes the surface morphology, average roughness, interface width, roughness exponent, and several other fractal parameters of the FTO surfaces. The UV–visible transmittance measurement shows an enhancement of transmittance in the ions irradiated substrates up to 95%. The electrical properties such as mobility, work-function, sheet resistance, and resistivity are also modified due to ions irradiation. In order to have functional applications of these ions irradiated substrates, we fabricated organic solar cells on these ions irradiated and pristine FTO substrates. The device performances are significantly improved for the case of ions irradiated FTO substrate in comparison to the pristine one. Thus, better device performance due to effective changes in physical properties suggests that the ions irradiated FTO substrates can be used as better electrodes for organic and hybrid photovoltaic device applications.

Thermoablative behaviors of designable hafnium carbonitride integrated with lattice of tungsten upon 3273K

Novel designed architecture of tailored HfC-HfN solid solution combined with laminated tungsten networks, spark plasma sintered at 2273 K with full density was investigated by multiple-characterizations in as-sintered and ablated states. The pristine substrate is composed of HfC0.72N0.28 solid solution and tungsten lattice with evident element diffusions. During long-time ablation(300 s) upon 3273 K the composites performed excellent anti-ablative performances and evolved into complex oxide scales, comprising condensed eutectic structures of HfO2-WO3 in the center and spindly HfO2 phase in the outer region. The tungsten networks contribute to the largely improved thermal shock resistances and oxidation resistances with increased viscosity of HfO2 melt.

Evolution of Topological Surface States Following Sb Layer Adsorption on Bi2Se3.

Thin antimony layers adsorbed on bismuth selenide () present an exciting topological insulator system. Much recent effort has been made to understand the synthesis and electronic properties of the heterostructure, particularly the migration of the topological surface states under adsorption. However, the intertwinement of the topological surface states of the pristine substrate with the Sb adlayer remains unclear. In this theoretical work, we apply density functional theory (DFT) to model heterostructures of single and double atomic layers of Sb on a bismuth selenide substrate. We thereby discuss established and alternative structural models, as well as the hybridization of topological surface states with the Sb states. Concerning the geometry, we reveal the possibility of structures with inverted Sb layers which are energetically close to the established ones. The formation energy differences are below 10 meV/atom. Concerning the hybridization, we trace the band structure evolution as a function of the adlayer-substrate distance. By following changes in the connection between the Kramers pairs, we extract a series of topological phase transitions. This allows us to explain the origin of the complex band structure, and ultimately complete our knowledge about this peculiar system.

Poly(vinyl alcohol)/reduced graphene oxide multilayered coatings: The effect of filler content on gas barrier and surface resistivity properties

Polymer-filler multilayered coatings fabricated by layer-by-layer (LbL) methods exhibit enhanced gas barrier properties alongside with transparency and flexibility. However, the traditional LbL methods which consist of repeated cycles of dipping (or spinning), washing, and drying, are time-consuming and complex to industrialize. Here, it is proposed an easy-operating and time-saving rod-coating assisted LbL method for the fabrication of poly(vinyl alcohol)/reduced graphene oxide (PVA/rGO) multilayered coatings on poly(ethylene terephthalate) (PET) substrates. Scanning electron microscopies revealed that PVA/rGO multilayered coatings exhibited a brick-and-wall structure with PVA able to bind the rGO buildings blocks. The oxygen transmission rate of the films coated with five layers of PVA/rGO coatings (8.4 cm3 m-2 day-1 atm-1) is about 92% lower than that of the uncoated PET substrate, whereas the optical transparency is still 94%. The water permeability of films coated with the multi-layered PVA/rGO coatings is about 30% lower than that of pristine PET substrate. Furthermore, the resulting films exhibited a low surface resistivity, which contrasts the negative effects of static electricity accumulation, and high mechanical property, fulfilling the technological requirements for traditional application in electronic packaging.

Enhancement of Photoelectrochemical Properties through α-Fe2O3 Deposition on a Modified Fluorine-Doped Tin Oxide

Hydrogen is attractive energy resource for renewable energy. In order to produce H2, several approaches are suggested. In particular, water splitting is well-known as an eco-friendly production approach. Moreover, electrochemical water splitting has a challenge that noble metal based catalyst. For this reason, photoelectrochemical (PEC) water splitting has been studied for a long time but not yet to reach a goal of society demand.For PEC water splitting, there are several materials has been considered such as Fe2O3, WO3, TiO2, BiVO4 etc. Among them, Fe2O3 is the most attractive material due to cheap, abundant resources and smaller bandgap than other material. However, it has a demerits of short life time owing to short diffusion length.In this research, we investigated enhancement of PEC performance with electrodeposited Fe2O3 on surface modified fluorine-doped tin oxide (FTO). The roughness of FTO substrates were increased with various electrochemistry method in acidic electrolyte. The modified FTO substrate area which leads to increasing electric conductivity. Under optimum condition photocurrent could be enhance with 20% in compare with α–Fe2O3 on pristine FTO substrate. Moreover, over-potential was also reduced with 100 mV. Figure 1

The Electronic State of Pt Nanoparticles on an Ion-Beam-Irradiated Carbon Support

Pt nanoparticle electrocatalysts on an Ar+-irradiated glassy carbon (GC) substrate were recently found to show a higher oxygen reduction reaction (ORR) activity than those on the non-irradiated one [1]. This finding suggests that the Pt nanoparticles would be electronically modified by the lattice defects in irradiated GC. Our theoretical research previously revealed that vacancies in graphite would lower a d-band center of the supported Pt nanoparticles; this is probably the reason for the higher activity [2]. We investigated here the electronic states of the interface between the Pt nanoparticles and the irradiated carbon support by X-ray absorption fine structure (XAFS) measurements in order to get an insight into the mechanism of the activity enhancement.Highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC) substrates were irradiated with 380 keV Ar+. The HOPG substrate was employed so that the electronic structure could be resolved into orbital components (σ and π bonds). The Pt nanoparticles were then deposited by RF magnetron sputtering. The Pt deposition was also done on the non-irradiated HOPG and GC substrates for comparison. The XAFS spectra were measured at BL14B1 in SPring-8 and at BL-8 of the SR Center, Ritsumeikan University.Figure 1 shows the C-K XAFS spectra for the pristine HOPG, the irradiated HOPG, Pt/non-irradiated HOPG, and Pt/irradiated HOPG. This spectral measurement was made at the X-ray incident angle of 30° to obtain the X-ray absorption due to C-C π* and s* orbitals with almost the same cross-section. The pristine and irradiated HOPG substrates exhibited three peaks from a C-C π* orbital (285.3 eV), C-C σ*, σ1 orbital (291.5 and 292.5 eV), and surface carbon with adsorbates (287.5 eV). The shoulder structure around 284 eV was observed for Pt/non-irradiated HOPG, indicating the occurrence of Pt-C interaction at the interface. The intensity of this shoulder increases for Pt/irradiated HOPG as shown by the arrow. Therefore, the vacancies in the irradiated carbon support would induce the change of Pt-C interaction, leading to the different electronic structure at the interface.Our previous paper reported that the Pt nanoparticles on the irradiated carbon support were distorted [3]. According to the result of Fig. 1, the Pt-C interaction could be an origin of the observed distortion of the Pt nanoparticles, which lowered the d band center and then improved their ORR activity. In this presentation, we will additionally clarify the electronic structure of Pt nanoparticles based on the XAFS results of Pt L edge.

Accessible Surface Area in Porous Carbon Electrodes and Its Impact on Redox Flow Battery Performance

Carbon-fiber electrodes exhibit many desirable material properties including conductivity, porosity, and chemical stability, and, accordingly, are employed in a range of electrochemical technologies.1 Such electrodes are particularly important in redox flow battery (RFB) systems, as they serve multiple critical functions including providing surface area for electrochemical reactions, distributing liquid electrolytes, and conducting electrons and heat. While commercially available materials possess suitable permeability and conductivity, the performance of pristine substrates is limited, thus oxidative treatment prior to use is common practice.2,3 Partial oxidation of the electrode surface has been shown to add a range of oxygen functional groups, which improve hydrophilicity and, in some cases, catalyze redox reactions, as well as to increase available surface area for the electrochemical reactions.4,5 Both effects are posited to improve electrode performance but their relative importance and effectiveness remains unclear.6 Here, we critically assess the nature of the surface area generated by thermal pretreatment in air and its role on RFB electrode performance. Using binder-free Freundenberg H23 as a model substrate, we systematically vary pretreatment time and temperature to create different surface morphologies and develop structure-function relations. First, we use Brauner Emmanuel Teller gas adsorption (e.g., N2, Kr, Ar/CO2) and mercury porosimetry to estimate physical surface area and pore size distribution. In parallel, we use voltammetry and impedance spectroscopy to determine electrochemically active surface area with different electrolyte compositions. In general, we find that only a fraction of the physical surface area is accessible for electrochemical redox reactions due, in large part, to the nanoscopic dimensions of the added surface area. Second, we develop a simple mathematical model to assess the effectiveness of the available surface area of carbon fibers for Faradaic reactions. We find that, under typical RFB operating conditions, external mass transfer limitations govern performance, limiting the utilization of recessed areas generated during pretreatment. Ultimately, these results highlight the potential limits of performance improvement strategies based on increasing surface area of fibrous substrates and motivate new approaches for electrode development. Acknowledgements The authors acknowledge the financial support of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the United States Department of Energy. K.V.G acknowledges additional funding from the National Science Foundation Graduate Research Fellowship. The authors acknowledge the Center for Nanoscale Systems and the NSF’s National Nanotechnology Infrastructure Network (NNIN) for the use of Nanoscale Analysis facility for electrode property characterization. References M. H. Chakrabarti et al., Journal of Power Sources, 253, 150–166 (2014).T. J. Rabbow, M. Trampert, P. Pokorny, P. Binder, and A. H. Whitehead, Electrochimica Acta, 173, 17–23 (2015).N. Pour et al., The Journal of Physical Chemistry C, 119, 5311–5318 (2015).B. Sun and M. Skyllas-Kazacos, Electrochim. Acta, 37, 8 (1992).T. J. Rabbow and A. H. Whitehead, Carbon, 111, 782–788 (2017).K. V. Greco, A. Forner-Cuenca, A. Mularczyk, J. Eller, and F. R. Brushett, ACS Applied Materials & Interfaces, 10, 44430–44442 (2018).

Critical Role of Surface Defects in the Controllable Deposition of Li2S on Graphene: From Molecule to Crystallite.

Uncontrollable electrochemical deposition of Li2S has negative impacts on the electrochemical performance of lithium-sulfur batteries, but the relationship between the deposition and the surface defects is rarely reported. Herein, ab initio molecular dynamics (AIMD) and density functional theory (DFT) approaches are used to study the Li2S deposition behaviors on pristine and defected graphene substrates, including pyridinic N (PDN) doped and single vacancy (SV), as well as the interfacial characteristics, in that such defects could improve the polarity of the graphene material, which plays a vital role in the cathode. The result shows that due to the constraint of molecular vibration, Li2S molecules tend to form stable adsorption with PDN atoms and SV defects, followed by the nucleation of Li2S clusters on these sites. Moreover, the clusters are more likely to grow near these sites following a spherical pattern, while a lamellar pattern is favorable on pristine graphene substrates. It is also discovered that PDN atoms and SV defects provide atomic-level pathways for the electronic transfer within the Li2S-electrode interface, further improving the electrochemical performance of the Li-S battery. It is found for the first time that surface defects also have strong impacts on the deposition pattern of Li2S and provide electronic pathways simultaneously. Our work demonstrated the interior relationship between the surface defects in carbon substrates and the stability of Li2S precipitates, which is of high significance to understand the electrochemical kinetics and design Li-S battery with long cycle life.

Rapid in-situ covalent crosslinking to construct a novel azo-based interlayer for high-performance nanofiltration membrane

The strategy of introducing a hydrophilic interlayer (IL) on the substrate has been widely used in the preparation of nanofiltration (NF) membranes. In this paper, we perform a rapid in-situ coupling reaction of tannic acid (TA) and a dual diazonium salt (DDS) to construct a novel stable azo-based interlayer on the polysulfone (PSf) ultrafiltration membrane. Through exploring the concentration and the deposition time of TA, the protocol of fabricating the interlayer with the optimal hydrophilicity is determined. Relevant characterizations indicate that the thickness of the interlayer is quite thin, and the defects at the surface of the pristine substrates disappear after modification. Interestingly, the color of the substrate with interlayer changes dramatically after pouring piperazine (PIP) solution thereon, implying that there is considerable interaction between the phenolic hydroxyl groups at the interlayer and the PIP molecules in aqueous phase. By further reducing the PIP concentration, an active layer of which thickness is only about 35 nm was obtained. The separation performance evaluation suggests that the optimized novel NF membrane exhibits a 2.71-fold increase in water permeance (17.40 ± 1.09 L m−2h−1 bar−1) compared with the conventional one. Moreover, the discussion about the role of the interlayer on interfacial polymerization (IP) is also provided with advanced significance.

Complete Prevention of Contact Electrification by Molecular Engineering

Summary Electrostatic charges are easily generated on surfaces during contact electrification. Although these invisible charges have emerged as a new dimension in mediating the functions of surfaces, such as energy conversion, liquid transport, reactivity, and adsorbability, the accumulation of charges on surfaces can also pose many undesirable consequences. Despite notable progress, existing approaches in engineering antistatic surfaces suffer from limitations such as the need to modify bulk materials or for delicate control of patterning on surfaces that rely on the neutralization of generated charges. Herein, we report a general toolbox for designing antistatic coatings by leveraging on chemically heterogeneous components with electron-donating and electron-accepting functions, i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyl trimethoxysilane, to molecularly engineer the surface potential to achieve an electrostatic homogeneity and completely prevent charge generation. Our approach is general, which allows the facile fabrication of antistatic coatings on various materials, even flexible and curved, with good re-writability and transparency.