There is still a debate about the effectiveness of globular proteins of several nanometers in stabilizing oil-in-water high internal phase emulsions (HIPEs). In this work, we report that a strong ...internal structural integrity and high refolding ability is one requirement for globular proteins to perform as soft particles to stabilize HIPEs. Using bovine serum albumin (BSA) as the model protein, it is demonstrated that BSA glycated with galactose (Gal), possessing a much stronger structural integrity and higher refolding ability, exhibited much improved HIPE emulsification performance and subsequent Pickering stabilization than native BSA. The underlying mechanism for the improvement is largely associated with the formation of a core-shell nanostructure with a hydrophilic Gal shell surrounding the protein core in glycated BSA. The ultra-stable HIPEs (gels) were stabilized by glycated BSA at a protein concentration in the aqueous phase as low as 0.1 wt%, much lower than that reported in the literature. These HIPEs exhibited a self-supporting gel network, an extraordinary stability upon long-term storage or against drastic heating as well as good freeze-thaw reversibility. The findings are of importance for the facile fabrication of biocompatible Pickering HIPE formulations with promising applications in the food, cosmetics and pharmaceutical fields.
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•Glycation of bovine serum albumin (BSA) with galactose led to formation of a very compact internal structure.•Glycated BSA was demonstrated to perform as an outstanding Pickering nanostabilizer for HIPEs.•The HIPEs stabilized by glycated BSA exhibited excellent stability against heating and long-term storage.•HIPE gels could be facily formed at low protein concentrations.•Glycated BSA stabilized the HIPEs through acting as soft nanoparticles.
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With the extensive consumption of non-renewable energy sources, storing solar energy as chemical energy has aroused people's wide concern. In this study, we successfully developed a novel Cu3P@NiCoP ...composite photocatalyst to produce hydrogen by splitting water under visible light irradiation. Both the building of a p–n heterojunction between Cu3P and NiCoP and the three-dimensional nanoflower structure of NiCoP play a vital role in improving the performance of the catalyst. On the one hand, the coupling of Cu3P and NiCoP built a p–n heterojunction at the photocatalyst interface, and the heterojunction could promote the separation efficiency of photogenerated carriers and prolong the life span of charges, therefore enhancing the photocatalytic hydrogen production activity. On the other hand, the excellent catalytic performance of the photocatalyst was benefited by the flower-like microsphere structure of NiCoP, which could provide abundant active sites and a large specific surface area, and promote the adsorption of protons by the photocatalyst. Besides, the phosphating degree of the precursors and the ratio of Cu3P and NiCoP were adjusted to get the best photocatalyst for hydrogen production, and the H2 production of the optimal catalyst could reach 8897.44 μmol h−1 g−1. This work provides a new understanding for the rational design of heterojunction photocatalysts for outstanding hydrogen production performance.
The catalyst MoC-QDs/C has a sufficient surface area and a unique lamellar structure, which provides a suitable position for the loading of Mo-S, so that the close contact and interfacial ...compatibility between MoC-QDs/C and Mo-S, and the smooth transfer of electrons through the carbon film (C) can be ensured. The catalyst MoC-QDs/C contains a large number of carbon films, and the carbon films have excellent conductive properties, so it can be used as a transfer channel for electrons to be transferred effectively, and the transferred electrons can be transmitted to MoC-QDs in time. The MoC-QDs act as the catalytic active center, which can effectively reduce H
+
to H
2
by the obtained electrons. This unique design can effectively separate the photogenerated electron-holes and promote the photocatalytic splitting of water for hydrogen production. By optimizing the composite catalyst, the best composite material 10%-MCC/M-S was obtained, which showed excellent hydrogen production activity (198.15 μmol) that was 2.67 times that of pure Mo-S (74.29 μmol) within 5 h, and the stability of the catalyst was proved by the cycle experiment. This work offers a new strategy and direction for the application of carbon films in the field of photocatalytic water decomposition for hydrogen production.
Carbon film contributes to the separation of photogenerated carriers in the process of photocatalytic hydrogen evolution.
There is fast increasing interest in the development of food-grade high internal phase emulsions (HIPEs). In the work, we reported that native soy β-conglycinin (β-CG; a major 7S globulin in ...soybeans) could perform as an outstanding Pickering-type stabilizer for oil-in-water HIPEs. The protein concentration in the continuous phase (c) for the formation of homogenous and gel-like HIPEs could be as low as 0.2 wt%; and increasing the c from 0.2 to 1.0 wt% led to a progressive decrease in droplet size, but a progressive increase in stiffness of the HIPEs. The fabricated HIPEs at low c values (e.g., 0.2–0.5 wt%) were a kind of HIPE gels in essence with a gel network that could not be disrupted by 6 M urea, while the HIPE at c = 1.0 wt% was a highly concentrated emulsion that could be diluted by water. All the HIPEs at c values of 0.2–1.0 wt% were extremely stable against heating (at 100 °C for 15 min), or an elongated storage up to 60 days, but they were very prone to a freeze-thawing treatment. The freeze-thawed HIPEs could be repeatedly recovered back to a similar state to the untreated ones, when subject to another emulsification, indicating an extraordinary temperature-responsiveness. The β-CG molecules suffered a structural dissociation at the quaternary conformational level into separate subunits when adsorbed at the oil-water interface. The dissociated subunits from adsorbed β-CG showed a similar tertiary and secondary conformation to that of native β-CG, confirming the Pickering-nature of these subunits. All the HIPEs exhibited a surface coverage of around 60% in regard to the subunits of β-CG. The findings would be of importance not only for extending the knowledge about the Pickering stabilization of HIPEs by native oligomeric globulins, but also for the development of novel, eco-friendly and sustainable HIPEs for food, cosmetic and medicine formulations.
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•Native β-conglycinin (β-CG) was demonstrated to be an outstanding Pickering nanostabilizer for HIPEs.•A kind of HIPE gels could be facilely formed at low concentrations (0.2–0.5 wt%).•The HIPEs or HIPE gels exhibited extraordinary stability against heating and storage.•The HIPEs were susceptibile to freeze-thawing, but could be recovered by another homogenization.•Dissociated subunits of β-CG at the interface were the factual stabilizers for the HIPEs.
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There is still a debate about the effectiveness of native globular proteins to perform as Pickering-like stabilizers for oil-in-water high internal phase emulsions (HIPEs). In the work, we report one ...native globular protein (ovalbumin) with strong structural integrity and high refolding ability, exhibits an outstanding Pickering stabilization for HIPEs. Ultrastable gel-like HIPEs can be formed through a facile one-pot homogenization even at a concentration as low as 0.2 wt %. The HIPEs formed in the protein-poor regime are a kind of self-supporting and remoldable hydrogel consisting of bridging droplets. The formed HIPEs also exhibit other unique characteristics, such as extraordinary coalescence stability (against prolonged storage or heating), susceptibility to freeze–thawing, enhanced oxidation stability (to encapsulated bioactives), and inhibited vaporization of volatile oils. The findings would be of importance for extending the HIPEs to be applied in food, cosmetic, and petroleum industries.
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Generally, cocatalyst modification is an efficient way to enhance the hydrogen evolution performance of visible light irradiation. In this work, CoP nanoparticles acted as a cocatalyst to modify the ...CdS/NiWO4 p–n heterojunction. The composite catalyst CdS/NiWO4/CoP was successfully prepared by a co-precipitation and physical mixing method. The maximum H2 production rate of the composite catalyst was 47.7 mmol h−1 g−1, which was 11.9 times and 3.3 times that of pure CdS and CdS/NiWO4 (50 wt%), respectively, and the apparent quantum efficiency was 9.7% in a 10% lactic acid system when the wavelength was 475 nm. This excellent performance is attributed to the CoP nanoparticles, which act as electron traps to provide more active sites and benefit electron transport. Photoluminescence spectroscopy and electrochemical performance analysis demonstrated that the composite catalyst had a better electron separation ability and light absorption conversion ability. Mott–Schottky and UV-visible diffuse reflectance testing indicated that the excellent electron and hole separation was due to the p–n junction formed between CdS and NiWO4, and the modification of the CoP cocatalyst further enhanced the charge-separation efficiency, thereby improving the hydrogen evolution activity.
The high hydrophilicity of cellulose nanocrystals (CNCs) greatly limits their application in the Pickering emulsion formulations. The work for the first time reports that a simple surface ...modification with octenyl succinic anhydride (OSA; food-grade) can remarkably improve the emulsification performance of CNCs, and facilitate the fabrication of the Pickering high-internal-phase-emulsions (HIPEs). The OSA modification occurred between the corresponding anhydride and the surface hydroxyl groups of CNCs, which remarkably increased their surface hydrophobicity. Stable and gel-like Pickering HIPEs with fine droplets could be easily fabricated using OSA-modified CNCs, even at very low particle concentrations in aqueous phase. The findings would be of crucial importance for greatly extending the applications of CNCs in emulsion formulations in the food and pharmaceutical fields.
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•Cellulose nanocrystals (CNCs) were chemically modified by octenyl succinic anhydride (OSA).•Surface hydrophobicity of CNCs was improved by OSA modification.•The OSA modification greatly improved the fabrication of Pickering HIPEs.•The HIPEs stabilized by modified CNCs exhibited a stronger gel-like behavior that those by unmodified CNC.
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High-performance and noble metal-free MoO3/Cd0.8Mn0.2S nanocomposites were synthesized via a simple direct physical mixing process. Consequently, from the many characterization methods, the obtained ...MoO3/Cd0.8Mn0.2S composites exhibited excellent photocatalytic hydrogen production performance and stability. The enhanced photocatalytic activity of the MoO3/Cd0.8Mn0.2S catalyst could be ascribed to the close contact interfaces and well-matched band structure of MoO3 and Mn0.8Cd0.2S, which is beneficial to the transport and separation of photonic excitons. Besides, the hydrogen production performance of the MoO3/Cd0.8Mn0.2S composite catalyst was 1.7 times higher than that of the pure MoO3. Based on the results of time-resolved fluorescence (TRPL) and electrochemical measurements, the possible S-scheme heterojunction mechanism of the photocatalytic hydrogen evolution of MoO3/Cd0.8Mn0.2S was proposed. This work has contributed to the transformation of solar energy into chemical energy.
In the field of catalysis, three critical factors for evaluating catalyst activity include charge separation efficiency, photoabsorption, and surface activity sites. In this work, we designed novel ...effective Mn0.05Cd0.95S/NiSe2 photocatalysts, which were formed by Mn0.05Cd0.95S (MCS) nanoparticles anchored on the outer surface of cubic NiSe2. The optimum hydrogen evolution rate of the Mn0.05Cd0.95S/NiSe2 composite is 14.3 mmol h−1 g−1, which is 7.5 times higher than that of single Mn0.05Cd0.95S. Multiple characterization techniques (XRD, SEM, TEM, XPS, PL, etc.) were performed to research the properties of the composite catalyst and propose a possible mechanism for hydrogen production by NiSe2/Mn0.05Cd0.95S. Structural analyses and experimental results reveal that attaching MCS particles to the surface of NiSe2 can significantly increase the visible light absorption capacity. Cubic NiSe2 can efficiently facilitate the separation of electron–hole pairs and expose abundant active sites for photocatalytic redox reactions. This work demonstrates that low-cost NiSe2 is a promising co-catalyst for the photocatalytic splitting of water to produce hydrogen.
Aiming to achieve the modification to soy protein isolate (SPI) by soy soluble polysaccharides (SSPS), electrically driven complex systems were first established in the environment of pH 3.0, and ...then reconstituted SPI particles with different SPI-SSPS ratios were obtained under freeze-drying process. Through this treatment, the structures of SPI particles were partly unfolded and adsorbed SSPS mainly via hydrophobic interactions and hydrogen bonding with larger particle sizes. The adherence of SSPS decreased the surface hydrophobicity of reconstituted SPI particles, but exerted not much influence on the emulsifying and foaming activities and increased the corresponding stabilities due to enhancing the unfolded extent of structure and improving the conformation flexibility. Reconstituted SPI-SSPS particles might rearrange and link each other due to the presence of SSPS on the air–water interface to better stabilize these systems. At SPI-SSPS ratio of 10:1, lower temperature was required to form gels with lower gel intensity and porous structure. The findings provide a further comprehension to the relationship between structures and functional properties of SPI modified by SSPS and the feasibility of applying these reconstituted particles to needed areas.
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