Broad pH Range Research Articles

Interfacial Hyperactivation of Candida rugosa Lipase onto Ca2Fe2O5 Nanoparticles: pH and Ionic Strength Fine-Tuning to Modulate Protein-Support Interactions.

The current study provides a comprehensive look of the adsorption process of Candida rugosa lipase (CRL) on Ca2Fe2O5 iron oxide nanoparticles (NPs). Protein-support interactions were identified across a broad range of pH and ionic strengths (mM) through a response surface methodology, surface charge determination, and spectroscopic and in silico analyses. The maximum quantity of immobilized protein was achieved at an ionic strength of 50 mM and pH 4. However, this condition did not allow for the greatest hydrolytic activity to be obtained. Indeed, it was recorded at acidic pH, but at 150 mM, where evaluation of the recovered activity revealed hyperactivation of the enzyme. These findings were supported by adsorption isotherms performed under different conditions. Based on zeta potential measurements, electrostatic interactions contributed differently to protein-support binding under the conditions tested, showing a strong correlation with experimentally determined immobilization parameters. Raman spectra revealed an increase in hydrophobicity around tryptophan residues, whereas the enzyme immobilization significantly reduced the phenylalanine signal in CRL. This suggests that this residue was involved in the interaction with Ca2Fe2O2 and molecular docking analysis confirmed these findings. Fluorescence spectroscopy showed distinct behaviors in the CRL emission patterns with the addition of Ca2Fe2O5 at pH 4 and 7. The calculated thermodynamic parameters indicated that the contact would be mediated by hydrophobic interactions at both pHs, as well as by ionic ones at pH 4. In this approach, this work adds to our understanding of the design of biocatalysts immobilized in iron oxide NPs.

Enhanced generation of reactive radicals and electrocatalytic oxidation of levofloxacin using a trimetallic CuFeV layered double hydroxide-containing electrode

In Electro-Fenton (EF) processes, the use of iron as a catalyst under acidic conditions results in increased costs and potential secondary pollution. To address these issues, we developed a CuFeV layered double hydroxide (LDH) coating on graphite felt (GF) (CuFeV LDH@GF) that offers an effective performance across a broad pH range without causing metal pollution. The CuFeV LDH@GF cathode exhibited a good oxygen reduction performance, high stability, and an efficient removal of levofloxacin (LEV) over a wide pH range (pH = 3–10). The simultaneous presence of Cu2+/Cu3+, Fe2+/Fe3+, and V4+/V5+ redox pairs played a crucial role in facilitating interfacial electron transfer, thereby enhancing the production and subsequent activation of H2O2 within the system. The apparent rate constant (kapp) of LEV removal under neutral conditions with the CuFeV LDH@GF electrode was more than twice that of the raw GF electrode. This improvement can be attributed to the CuFeV LDH coating, which increased the generation of hydroxyl radicals (•OH) from 0.64 to 1.27 mM. Importantly, the CuFeV LDH@GF electrode maintained its efficiency and stability even after 10 reuse cycles. Additionally, GC–MS analyses revealed the degradation of intermediate compounds, which included cyclic and aliphatic compounds. This study provides significant insights into the synergistic effects of trimetallic LDHs, contributing to the development of high-performance cathodes.

Effect of pH of Ganoderma lucidum aqueous extract on green synthesis of silver nanoparticles

Perspective applications of Ag nanoparticles (NPs) stimulate intense research on their affordable synthesis, including green routes. The use of fungi extracts has advantages over other organisms, because of their relatively easy isolation and higher efficiency in a reduction of metal ions and NP formation. Here we report mycosynthesis of AgNPs based on Ganoderma lucidum fruit body extract with different pH values as the bioreducing and stabilising agent. Stable NPs colloids with distinct plasmonic resonance peaking at 408–418 nm are obtained by using photoreduction in a broad pH range (5 to 11). Synthesis efficiency drops only at very acidic conditions, pH = 2.5. The NP size and morphology are studied by dynamic light scattering and scanning electron microscopy. An analysis of FTIR spectra of pure analyte and NP sample indicates that stabilisation of the AgNPs by the components of Ganoderma lucidum extract may take place via forming chemical bonds with the NP surface. These bio-friendly AgNPs are both optically and chemically active, as inferred from surface-enhanced Raman scattering of a standard dye analytes and charge transfer-induced quenching of the photoluminescence of both dye and inorganic NPs, and can be studied for various applications which require direct access to the AgNP surface.

A comparative study of methylene blue adsorption and removal mechanisms by calcium carbonate from different sources

Efficient removal of organic dye pollution from contaminated water is a concern in the absorbent applications. In this study, a green biogenic calcium carbonate (BCC) absorbent was fabricated using Bacillus licheniformis for the removal of methylene blue (MB) from water. This was found to have superior adsorption capacity compared with abiotic calcium carbonate (ACC) and operate within a broad pH range from 3 to 9. MB adsorption on BCC was physical and exothermic. The hydrophobic features, rough nanoporous microstructure, and organic–inorganic mesoporous structure of the BCC may all be responsible for its favorable adsorption mass transfer. The adsorption energy of BCC had a more negative value than that of ACC, indicating a stronger MB interaction with BCC with a lower energy barrier. Hydrogen bonding and electrostatic attraction were involved in the adsorption process. Overall, the findings established a theoretical foundation for the application of BCC in remediation of MB-contaminated water.

PdPt Alloy Nanoframes with Rugged Surfaces: Efficient Bifunctional Fuel Cell Catalysts in a Broad pH Range

PdPt Alloy Nanoframes with Rugged Surfaces: Efficient Bifunctional Fuel Cell Catalysts in a Broad pH Range

Polymorphic amyloid nanostructures of hormone peptides involved in glucose homeostasis display reversible amyloid formation

A large group of hormones are stored as amyloid fibrils in acidic secretion vesicles before they are released into the bloodstream and readopt their functional state. Here, we identify an evolutionarily conserved hexapeptide sequence as the major aggregation-prone region (APR) of gastrointestinal peptides of the glucagon family: xFxxWL. We determine nine polymorphic crystal structures of the APR segments of glucagon-like peptides 1 and 2, and exendin and its derivatives. We follow amyloid formation by CD, FTIR, ThT assays, and AFM. We propose that the pH-dependent changes of the protonation states of glutamate/aspartate residues of APRs initiate switching between the amyloid and the folded, monomeric forms of the hormones. We find that pH sensitivity diminishes in the absence of acidic gatekeepers and amyloid formation progresses over a broad pH range. Our results highlight the dual role of short aggregation core motifs in reversible amyloid formation and receptor binding.

Heterogenous electro-Fenton degradation of sulfamethoxazole on a polyethylene glycol-coated magnetite nanoparticles catalyst

We report the preparation and application of poly (ethylene) glycol (PEG) coated magnetite nanoparticles (MNPs) catalyst for the heterogeneous electro-Fenton (HEF) degradation of sulfamethoxazole in real wastewater PEG-coated MNPs of four MNP:PEG ratios were synthesised using the co-precipitation method. The synthesised MNP were characterised using FTIR, XRD, EDX, TEM, and CHN elemental analysis. It was observed that the coating of MNP with PEG influences the nanoparticle size, agglomeration tendencies and catalytic efficiency of MNPs properties in the HEF degradation process. A 1:1 optimal MNP:PEG catalyst yielded 91% sulfamethoxazole degradation and 48% total organic carbon removal in 60 min, which is an improvement of 11% over degradation with the uncoated MNP. The PEG-coated MNP showed higher stability in 10 consecutive reaction cycles, reduced leaching, and improved performance at a lower dosage and broader pH range than the uncoated MNPs. These results show that coating MNP with PEG enhances HEF catalytic performance in the degradation of sulfamethoxazole in wastewater.

One-step synthesis of thiol-functionalized metal coordination polymers: effective and superfast removal of Hg (II) in the different matrices to ppb level

The mercury in water bodies has posed a great threat to the environment and humans, and removing mercury and purifying wastewater has become a global environmental issue. Adopting Zn(II) coordination polymers (Zn-CPs) emerged as a new approach, however, the kind of Zn-CPs, which solely consisted of amino groups, exhibited unsatisfactory performance in capturing Hg(II) at a low level and causing the subsequent leaching of Zn(II) after adsorption. In this study, we fabricated the thiol-modified Zn-based coordination polymers (Zn-CPs-SH) through a one-step solvothermal reaction to efficiently capture Hg(II) from wastewater. Its preeminent adsorption performance could be maintained across a broad range of pH (2–7), ion strength (Cl−, SO42−, and NO3− at 0–10,000 mg/L), and dissolved organic matter (0–100 mg/L). The impressive properties, including fast kinetics (k2∼1.01 × 10−4 L/min), outstanding adsorption capacity (1278.72 mg/g, 298 K), superior selectivity (Kd∼2.3 × 104 mL/g), and excellent regeneration capability (Re = 93.54% after 5 cycles), were attributed to the ultra-abundance of adsorption sites donating from thiol groups, which was revealed by XPS analysis, DFT calculations, and molecular orbital theory. Noteworthy, the high practical application potential of Zn-CPs-SH was demonstrated by its outstanding Hg(II) removal efficiency (Re ≥ 99.10%) in various Hg(II)-spiked water matrices, e.g., tap water, river water, and industrial wastewater. Importantly, the residual Hg(II) in the treated water declined to the ppb level without any Zn(II) leaching. Overall, it is highly anticipated that the incorporation of Zn-CPs-SH would facilitate the practical implementation of highly efficient Hg(II) removal in wastewater treatment owing to its exhibiting high selective affinity, superior adsorption capacity, and enhanced efficiency.

The effects of saline water on the recovery of lead and zinc sulfide during froth flotation

In this study, we investigated the effects of water salinity on the flotation performance of pure lead and zinc sulfide mineral samples as well as a Pb/Zn complex sulfide ore by means of micro-flotation and batch flotation experiments. Our results showed higher PbS and ZnS recoveries in more concentrated NaCl salt solutions. The results for the experiments using seawater demonstrated that in the presence of additional ions, such as Ca2+ and Mg2+, the recovery of PbS and ZnS was significantly reduced.As part of this investigation, we developed and implemented a surface complexation model for ZnS based on the presence of two differently charged surface sites. Zeta potential measurements of ZnS particles were used to optimise the parameters of our model. It was found that the surface potentials calculated using this model were in good agreement with the experimental zeta potentials, validating the model for predicting the zeta potential behaviour of ZnS particles over a broad range of pH and NaCl concentrations.Additionally, total interaction free energies were determined as a function of separation distance, representing particle–particle and particle-bubble interactions of our study in different NaCl concentrations. The theoretical analyses showed that asymmetric Pb/Zn particle–particle interactions were repulsive at lower NaCl concentrations, before becoming purely attractive at higher NaCl concentrations. For the case of the symmetric particle–particle interactions, attraction controlled all interactions, regardless of NaCl concentration. The calculated PbS-bubble interactions were repulsive in lower NaCl concentrations but became increasingly attractive in higher NaCl concentrations. Strong repulsions controlled all ZnS-bubble interactions, and these interactions remained repulsive with increasing NaCl concentration. The theoretical projections presented in this study were in good agreement with the measured saline water flotation phenomena.

PH-Dependent Solution Micellar Structure of Amphoteric Polypeptoid Block Copolymers with Positionally Controlled Ionizable Sites.

While solution micellization of ionic block copolymers (BCP) with randomly distributed ionization sites along the hydrophilic segments has been extensively studied, the roles of positionally controlled ionization sites along the BCP chains in their micellization and resulting micellar structure remain comparatively less understood. Herein, three amphoteric polypeptoid block copolymers carrying two oppositely charged ionizable sites, with one fixed at the hydrophobic terminus and the other varyingly positioned along the hydrophilic segment, have been synthesized by sequential ring-opening polymerization method. The presence of the ionizable site at the hydrophobic segment terminus is expected to promote polymer association toward equilibrium micellar structures in an aqueous solution. The concurrent presence of oppositely charged ionizable sites on the polymer chains allows the polymer association to be electrostatically modulated in a broad pH range (ca. 2-12). Micellization of the amphoteric polypeptoid BCP in dilute aqueous solution and the resulting micellar structure at different solution pHs was investigated by a combination of scattering and microscopic methods. Negative-stain transmission-electron microscopy (TEM), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) analyses revealed the dominant presence of core-shell-type spherical micelles and occasional rod-like micelles with liquid crystalline (LC) domains in the micellar core. The micellar structures (e.g., aggregation number, radius of gyration, chain packing in the micelle) were found to be dependent on the solution pH and the position of the ionizable site along the chain. This study has highlighted the potential of controlling the position of ionizable sites along the BCP polymer to modulate the electrostatic and LC interactions, thus tailoring the micellar structure at different solution pH values in water.

Isolation and characterization of a cold-active, detergent-stable protease from Serratia sp. TGS1.

Psychrophiles are cold-adapted microorganisms living in cold regions and are known to generate cold-active enzymes such as proteases, lipases, and peptidases. These types of enzymes are a major part of the market of the food and textile sector. This study aimed to isolate and characterize the cold-active and detergent-stable, extracellular protease from psychotrophic bacteria Serratia sp. TGS1 (OQ654005). Protease was purified by gel permeation chromatography using Sephadex G-75. The specific activity of the purified protease was 250 U/mg at 15°C, with a purification fold of 5.68 and a percentage yield of 60%. The cold active protease was stable within a temperature range of 5-30°C and a pH range of 6-10. Ca+2 and Mg+2 enhanced its activity while chelators like ethylenediaminetetraacetic acid inhibited cold active protease, showing it as metalloprotease in nature. The enzyme was sensitive to Cu+2 , Zn+2 , and Hg+2 , and the proteolytic activity decreased upon treatment with heavy metals. The molecular weight of the protease was estimated to be 47 kDa using sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Proteins within a specific range of molecular weight possess desirable properties for industrial enzyme use. By working on a specific range, the researchers intended to examine an enzyme to examine its specific characteristics. The purified protease showed high stability to detergents like SDS, Tween 20, Tween 60, and Triton X. The maximum velocity Vmax and Km values were 59.90 mg/min/mL and 1.53 mg/mL, respectively. The obtained protease exhibited an interesting activity at a broad range of pH (6-10) and stability at low temperatures (5-30°C) and detergents. Such enzymatic features of versatile and potent cold-active enzymes enhance their industrial applications to meet food, dairy, and laundry requirements.

High-efficiency refractory organic pollutants removal boosted by combining heterogeneous electro-Fenton with electrochemical anodic oxidation over a broad pH range

Electrochemical anodic oxidation (AO) is a green and efficient treatment process for refractory pollutants degradation. The cathode in AO process generally serves as the counter electrode, and does not contribute significantly for pollutants removal. The heterogeneous electro-Fenton (EF) process uses the bifunctional catalytic material as cathode to produce H2O2 via 2e- oxygen reduction reaction and activate H2O2 decomposition to generate •OH for degrading pollutants. Herein, we investigated an integrated electrocatalytic process between heterogeneous EF and AO (EF+AO) to enhance refractory pollutants removal over a broad pH range without the production of iron-containing sludge. Total organic carbon removal of phenol by EF+AO was 98.2 % in 180 min under pH ∼5.9 and the applied current density of 1.0 mA cm−2, obviously higher than that of only EF (48.8 %) or AO (56.9 %). Significantly, EF+AO process can efficiently treat the actual coking wastewater that the chemical oxygen demand (COD) value gradually decreased from 312.3 mg L−1 to 47.8 mg L−1 with the low specific energy consumption of 14.0 – 25.7 kWh·(kg COD)−1. This process delivered excellent long-term durability in flow mode, retaining efficient degradation performance for phenol during 100 h of consecutive runs. Our results provide new insights into developing an energy-efficient electrocatalytic process for pollutants removal.

Distinct Cleavage Properties of Cathepsin B Compared to Cysteine Cathepsins Enable the Design and Validation of a Specific Substrate for Cathepsin B over a Broad pH Range.

The biological and pathological functions of cathepsin B occur in acidic lysosomes and at the neutral pH of cytosol, nuclei, and extracellular locations. Importantly, cathepsin B displays different substrate cleavage properties at acidic pH compared to neutral pH conditions. It is, therefore, desirable to develop specific substrates for cathepsin B that measure its activity over broad pH ranges. Current substrates used to monitor cathepsin B activity consist of Z-Phe-Arg-AMC and Z-Arg-Arg-AMC, but they lack specificity since they are cleaved by other cysteine cathepsins. Furthermore, Z-Arg-Arg-AMC monitors cathepsin B activity at neutral pH and displays minimal activity at acidic pH. Therefore, the purpose of this study was to design and validate specific fluorogenic peptide substrates that can monitor cathepsin B activity over a broad pH range from acidic to neutral pH conditions. In-depth cleavage properties of cathepsin B were compared to those of the cysteine cathepsins K, L, S, V, and X via multiplex substrate profiling by mass spectrometry at pH 4.6 and pH 7.2. Analysis of the cleavage preferences predicted the tripeptide Z-Nle-Lys-Arg-AMC as a preferred substrate for cathepsin B. Significantly, Z-Nle-Lys-Arg-AMC displayed the advantageous properties of measuring high cathepsin B specific activity over acidic to neutral pHs and was specifically cleaved by cathepsin B over the other cysteine cathepsins. Z-Nle-Lys-Arg-AMC specifically monitored cathepsin B activity in neuronal and glial cells which were consistent with relative abundances of cathepsin B protein. These findings validate Z-Nle-Lys-Arg-AMC as a novel substrate that specifically monitors cathepsin B activity over a broad pH range.

Structure, Biology, and Applications of Filamentous Bacteriophages.

The closely related Escherichia coli Ff filamentous phages (f1, fd, and M13) have taken a fantastic journey over the past 60 years, from the urban sewerage from which they were first isolated, to their use in high-end technologies in multiple fields. Their relatively small genome size, high titers, and the virions that tolerate fusion proteins make the Ffs an ideal system for phage display. Folding of the fusions in the oxidizing environment of the E. coli periplasm makes the Ff phages a platform that allows display of eukaryotic surface and secreted proteins, including antibodies. Resistance of the Ffs to a broad range of pH and detergents facilitates affinity screening in phage display, whereas the stability of the virions at ambient temperature makes them suitable for applications in material science and nanotechnology. Among filamentous phages, only the Ffs have been used in phage display technology, because of the most advanced state of knowledge about their biology and the various tools developed for E. coli as a cloning host for them. Filamentous phages have been thought to be a rather small group, infecting mostly Gram-negative bacteria. A recent discovery of more than 10 thousand diverse filamentous phages in bacteria and archaea, however, opens a fascinating prospect for novel applications. The main aim of this review is to give detailed biological and structural information to researchers embarking on phage display projects. The secondary aim is to discuss the yet-unresolved puzzles, as well as recent developments in filamentous phage biology, from a viewpoint of their impact on current and future applications.

Selective and high capacity recovery of aqueous Ag(I) by thiol functionalized mesoporous silica sorbent

A simplified sol–gel method was developed for the preparation of thiol functionalized porous silica particles using (3-mercaptopropyl)-trimethoxy-silane (MPTMS) for co-gelation in the presence of micellar templates. The resulting short range ordered porous silica microparticles are exceptionally effective sorbents of aqueous Ag(I). The binding of aqueous Ag(I) is almost stoichiometric in the broad pH range between 4.0 and 9.0 even at low Ag(I) concentrations until reaching the limiting 238 mg g−1 sorption capacity. The sorbent displays high selectivity towards Ag(I), which was tested in the simultaneous presence of several different metal compounds. The practically complete recovery of Ag(I) and the regeneration of the sorbent was achieved by washing with a 10 mM Na2S2O3 solution. X-ray photoelectron spectroscopy (XPS) revealed that silver is not reduced on the surface of the sorbent. The reason for the strong and selective binding of Ag(I) is the formation of layered thiolate coordination compounds on the functionalized silica surface that display characteristically high stability even in the presence of other competing metal ions.

Glycogen availability and pH variation in a medium simulating vaginal fluid influence the growth of vaginal Lactobacillus species and Gardnerella vaginalis

BackgroundGlycogen metabolism by Lactobacillus spp. that dominate the healthy vaginal microbiome contributes to a low vaginal pH (3.5–4.5). During bacterial vaginosis (BV), strict and facultative anaerobes including Gardnerella vaginalis become predominant, leading to an increase in the vaginal pH (> 4.5). BV enhances the risk of obstetrical complications, acquisition of sexually transmitted infections, and cervical cancer. Factors critical for the maintenance of the healthy vaginal microbiome or the transition to the BV microbiome are not well defined. Vaginal pH may affect glycogen metabolism by the vaginal microflora, thus influencing the shift in the vaginal microbiome.ResultsThe medium simulating vaginal fluid (MSVF) supported growth of L. jensenii 62G, L. gasseri 63 AM, and L. crispatus JV-V01, and G. vaginalis JCP8151A at specific initial pH conditions for 30 d. L. jensenii at all three starting pH levels (pH 4.0, 4.5, and 5.0), G. vaginalis at pH 4.5 and 5.0, and L. gasseri at pH 5.0 exhibited the long-term stationary phase when grown in MSVF. L. gasseri at pH 4.5 and L. crispatus at pH 5.0 displayed an extended lag phase over 30 d suggesting inefficient glycogen metabolism. Glycogen was essential for the growth of L. jensenii, L. crispatus, and G. vaginalis; only L. gasseri was able to survive in MSVF without glycogen, and only at pH 5.0, where it used glucose. All four species were able to survive for 15 d in MSVF with half the glycogen content but only at specific starting pH levels – pH 4.5 and 5.0 for L. jensenii, L. gasseri, and G. vaginalis and pH 5.0 for L. crispatus.ConclusionsThese results suggest that variations in the vaginal pH critically influence the colonization of the vaginal tract by lactobacilli and G. vaginalis JCP8151A by affecting their ability to metabolize glycogen. Further, we found that L. jensenii 62G is capable of glycogen metabolism over a broader pH range (4.0–5.0) while L. crispatus JV-V01 glycogen utilization is pH sensitive (only functional at pH 5.0). Finally, our results showed that G. vaginalis JCP8151A can colonize the vaginal tract for an extended period as long as the pH remains at 4.5 or above.

Structural and Functional Characterization of Drosophila melanogaster α-Amylase.

Insects rely on carbohydrates such as starch and glycogen as an energy supply for growth of larvae and for longevity. In this sense α-amylases have essential roles under extreme conditions, e.g., during nutritional or temperature stress, thereby contributing to survival of the insect. This makes them interesting targets for combating insect pests. Drosophila melanogaster α-amylase, DMA, which belongs to the glycoside hydrolase family 13, sub family 15, has been studied from an evolutionary, biochemical, and structural point of view. Our studies revealed that the DMA enzyme is active over a broad temperature and pH range, which is in agreement with the fluctuating environmental changes with which the insect is confronted. Crystal structures disclosed a new nearly fully solvated metal ion, only coordinated to the protein via Gln263. This residue is only conserved in the subgroup of D. melanogaster and may thus contribute to the enzyme adaptive response to large temperature variations. Studies of the effect of plant inhibitors and the pseudo-tetrasaccharide inhibitor acarbose on DMA activity, allowed us to underline the important role of the so-called flexible loop on activity/inhibition, but also to suggest that the inhibition modes of the wheat inhibitors WI-1 and WI-3 on DMA, are likely different.

Notably Stable Bifunctional Europium-Centered Metal-Organic Framework for Instant Sensing of Uric Acid and 1-Hydroxypyrene in Human Urine.

A new Eu-centered metal-organic framework, [(CH3)2NH2][Eu(cdip)(H2O)] (compound 1), was fabricated by the reaction of Eu(NO3)3·6H2O and a high-symmetry ligand, 5,5'-carbonyldiisophthalic acid (H4cdip). Interestingly, compound 1 exhibits extraordinary stability, including air, thermal, and chemical stabilities, in an aqueous solution with a broad pH range of 1-14, which is rarely seen in the field of metal-organic framework materials. Notably, compound 1 is proved to be an exceptional prospective luminescent sensor for recognizing 1-hydroxypyrene and uric acid both in DMF/H2O solution and human urine with a fast response (1-HP: 10 s; UA: 80 s), high quenching efficiency Ksv (7.01 × 104 M-1 for 1-HP and 5.46 × 104 M-1 for UA in DMF/H2O solution; 2.10 × 104 M-1 for 1-HP and 3.43 × 104 M-1 for UA in human urine), low limit of detection (1.61 μM for 1-HP and 0.54 μM for UA in DMF/H2O solution; 0.71 μM for 1-HP and 0.58 μM for UA in human urine), and remarkable anti-interference ability based on luminescence-quenching effects observable by the naked eye. This work provides a new strategy for the exploration of potential luminescent sensors based on Ln-MOFs for 1-HP, UA, or other biomarkers in biomedical and biological fields.

Facile fabrication of robust superhydrophobic polyurethane sponge modified with polydopamine- silica nanoparticle for effective oil/water separation

Porous superhydrophobic materials with high mechanical stability have a significant amount of potential for oil-water separation in practice. In this study, a superhydrophobic material with strong hydrophobic coating adhesion was developed using a polyurethane sponge. The interior and exterior surfaces of the porous polyurethane material were coated using a two-step technique. The sponge was treated with poly (dopamine) to modify its skeleton, allowing the second layer to adhere readily. The second layer of silica applied to the surface of the sponge functions as a superhydrophobic layer. The modified sponge's water contact angle was approximately 156.2° ± 5°, compared to 78° ±2° for the original sponge, demonstrating its superhydrophobic nature. The fabricated sponge is capable of separating and absorbing 43.3–51 times of its initial mass from an oil-water mixture, depending on the type of oil used in the test. Fifteen cycles of oil-water separation were followed by chemical cleaning of the hydrophobic sponge. After undergoing these cycles, the hydrophobic nature and absorption capacity of the produced sponge were preserved. Over a broad pH range, the hydrophobicity of the superhydrophobic sponge was studied, and the results indicated that hydrophobicity was substantially maintained even under harsh pH operating conditions. The water contact angle of the sponge was measured to be 145° ± 1° and 140° ± 1°, respectively, after 12 h of immersion in strong acids and bases.

Modulating the electronic structure of Mo2C/MoP heterostructure to boost hydrogen evolution reaction in a wide pH range

Interface engineering is an effective strategy for the design of electrochemical catalysts with attractive performance for hydrogen evolution reaction. Herein, the Molybdenum carbide/molybdenum phosphide (Mo2C/MoP) heterostructure deposited on nitrogen (N), phosphorous (P) co-doped carbon substrate (Mo2C/MoP-NPC) is fabricated by one-step carbonization. The electronic structure of Mo2C/MoP-NPC is changed by optimizing the ratio of phytic acid and aniline. The calculation and experimental results also show that there is an electron interaction on the Mo2C/MoP interface, which optimizes the adsorption free energy of hydrogen (H) and improves the performance of hydrogen evolution reaction. Mo2C/MoP-NPC exhibits significant low overpotentials at 10 mA·cm−2 current density, 90 mV in 1 M KOH and 110 mV in 0.5 M H2SO4, respectively. In addition, it shows superior stability over a broad pH range. This research provides an effective method for the construction of novel heterogeneous electrocatalysts and is conducive to the development of green energy.