The rational design of heterojunction photocatalysts with unique mesoporous structure is of significant importance for obtaining enhanced conversion efficiency of solar energy to hydrogen energy. In ...present work, for the first time, anatase-TiO
2
/rutile-TiO
2
/ZnTiO
3
(TiO
2
(A-R)/ZnTiO
3
) heterojunction photocatalysts with a unique mesoporous structure were synthetized by a foaming agent assisted electrospinning method. The obtained mesoporous TiO
2
(A-R)/ZnTiO
3
nanofibers photocatalyst showed the highest hydrogen generation rate (887.7 μmol·g
−1
·h
−1
) without use of any co-catalytic noble metals, which was approximately 2.0, 2.2 and 1.4 times higher than those of ordinary solid TiO
2
(A-R)/ZnTiO
3
, mesoporous TiO
2
(A-R) and mesoporous TiO
2
(A)/ZnTiO
3
nanofibers, respectively. Significantly, the archived hydrogen generation rate is also better or comparable to the some ever reported 1D TiO
2
based photocatalysts. The unique 1D mesoporous nanostructure would make the reactants and products migrating easily into/out of the photocatalyst while the closely-coupled triphase heterojunction can significantly favor the separation of photogenerated electron–hole pairs, thus synergistically contributing to the improved photocatalytic activity. We also proposed that three types of charge transfer routes over the heterojunction photocatalysts, named “waterfall”, “concave” and “convex”, might concurrently promote the separation of photoinduced electrons and holes in this triphase photocatalyst system, thereby efficiently boost the photocatalytic hydrogen production activity.
Graphic Abstract
In consideration of the urgency to replace fossil fuel-based energy sources with renewable sources, one should do much to develop efficient photocatalyst that are capable of converting solar energy ...into hydrogen fuel. This work describes the atomic layer deposition (ALD) of ZnO on electrospinning TiO
2
nanofibers to form a 1D TiO
2
@ZnO heterojunction. The obtained TiO
2
@ZnO composite were systematically investigated to reveal their structural and morphological properties by using SEM, BET, XRD, and TEM with EDX spectroscopy. The TiO
2
@ZnO hybrids showed enhanced photocatalytic activity towards hydrogen production as compared to the pure TiO
2
nanofibers. The optimum hydrogen production rate was reaching to 1190.9 μmol/h
/
g without use of any co-catalytic noble metals, which is 6.5 folds higher than that of bare TiO
2
counterpart, and also better or comparable to the ever reported TiO
2
@ZnO photocatalysts. Based on the mechanism analysis, the Type-II heterojunction charge transfer route was responsible for the boosted performance over the TiO
2
@ZnO composite.
Graphic Abstract
In this work, a polyethyleneimine-grafted graphene oxide (PEI-GO) hybrid material was prepared as an effective filler to improve the anticorrosion performance of waterborne epoxy coating. The ...successful covalent reaction between PEI and GO was confirmed by FTIR, Raman, XPS, XRD and TGA measurement. The epoxy coating filled with modified and unmodified graphene oxide was characterized by SEM and Raman spectroscopy. The results showed that PEI-GO was uniformly dispersed in the epoxy matrix. It was found that the PEI-GO hybrid materials displayed considerable superiorities in improving corrosion resistance of epoxy coating by EIS and SVET. Besides, the optimal content (0.25 wt%) of PEI-GO was obtained through experimental results. Moreover, the desirable anticorrosive property of PEI-GO/EP composite coating is proposed to be mainly attributed to the role of PEI, which fully stimulated the barrier properties of graphene oxide by improving its dispersion in the epoxy coating and also enhanced the crosslink density of epoxy resin by increasing the surface activity of the graphene oxide to the epoxy groups.
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•Polyethylenimine (PEI) was grafted on graphene oxide (GO) surface.•The PEI-GO hybrid improved the compatibility between GO and epoxy resin (EP).•The PEI-GO/EP composite coating had longer service life and better anti-corrosion property.•The presence of PEI-GO hybrid increased the density of epoxy coating and suppressed the corrosion of metal substrate.
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•Cu2O particles with similar size and controllable morphologies were fabricated.•The relationship between morphology of Cu2O particles and their antibacterial properties was build ...up.•The cubooctahedron-Cu2O hybrid coating exhibited the best antibacterial capacity.•Copper ion and reactive oxygen species are key factors to the antibacterial capacity of Cu2O particles.
Biofouling, a global issue, exerts an adverse impact on ocean shipping, deep-sea exploration, aquaculture and other industries. The addition of Cu2O particles to coatings is the most popular and effective method used for biofouling resistance in the ocean circumstance. Herein, Cu2O particles with three kinds of morphologies, including cube, sphere and cubooctahedron, were fabricated by liquid phase reducing method. Particle size, crystallinity, component, activity in aqueous solution, antibacterial property and copper ion leaching rate were systematically investigated. XRD and XPS jointly reflected that as-prepared Cu2O particles were highly pure and impurity was absent. Among three kinds of Cu2O particles, cubooctahedron Cu2O was the most active, possessed the highest ion leaching rate and exhibited the best antibacterial property. It could be deduced that morphology of Cu2O particles affected its activity in aqueous solution, then impacted release rate and ultimately influenced antibacterial capacity. Morphology and component of bacteria, before and after being exposed to as-synthesized Cu2O-acrylic hybrid coatings were also studied and results proved that copper ion was prone to do a damage to the cell membrane of E.coli rather than B. subtilis because of the difference between cell walls.
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•GO with different aspect ratios were prepared and the uniform GO/epoxy composite coatings were fabricated.•Anti-corrosion performance of composite coatings containing GO sheets with ...different aspect ratio were investigated.•Anti-corrosion mechanism of different GO/epoxy composite coatings were studied.•The aspect ratio of GO sheets was a significant factor for enhancing corrosion resistance of GO/epoxy coatings.
Graphene oxide (GO) has a wide application prospect in the field of metal protection due to its good dispersion, chemical activity and physical barrier property. Herein, graphene oxide sheets with different aspect ratio were first prepared by simply controlling the procedure of chemical exfoliation and then used to fabricate GO/epoxy composite coatings. The morphology and structural features of as-prepared GO sheets were characterized by Raman spectroscopy, X-ray diffraction and atomic force microscopy. The dispersion and anticorrosive performances of GO with different aspect ratios incorporated in epoxy-based waterborne composite coatings were investigated by Raman spectroscopic mapping, electrochemical measurements and scanning vibrating electrode technique. The results demonstrated that the different types of GO showed homogeneous dispersion in epoxy resin and GO with higher aspect ratio exhibited larger corrosion protection potential. Furthermore, the anti-corrosion mechanisms for composite coatings enhanced via GO with different aspect ratio were tentatively proposed, which indicating that the GO sheets with higher aspect ratio provided a more tortuous permeation path for corroding medium and thus displayed better corrosion resistance.
The rational design of heterojunction photocatalysts with unique mesoporous structure is of significant importance for obtaining enhanced conversion efficiency of solar energy to hydrogen energy. In ...present work, for the first time, anatase-TiO.sub.2/rutile-TiO.sub.2/ZnTiO.sub.3 (TiO.sub.2(A-R)/ZnTiO.sub.3) heterojunction photocatalysts with a unique mesoporous structure were synthetized by a foaming agent assisted electrospinning method. The obtained mesoporous TiO.sub.2(A-R)/ZnTiO.sub.3 nanofibers photocatalyst showed the highest hydrogen generation rate (887.7 mumol·g.sup.-1·h.sup.-1) without use of any co-catalytic noble metals, which was approximately 2.0, 2.2 and 1.4 times higher than those of ordinary solid TiO.sub.2(A-R)/ZnTiO.sub.3, mesoporous TiO.sub.2(A-R) and mesoporous TiO.sub.2(A)/ZnTiO.sub.3 nanofibers, respectively. Significantly, the archived hydrogen generation rate is also better or comparable to the some ever reported 1D TiO.sub.2 based photocatalysts. The unique 1D mesoporous nanostructure would make the reactants and products migrating easily into/out of the photocatalyst while the closely-coupled triphase heterojunction can significantly favor the separation of photogenerated electron-hole pairs, thus synergistically contributing to the improved photocatalytic activity. We also proposed that three types of charge transfer routes over the heterojunction photocatalysts, named "waterfall", "concave" and "convex", might concurrently promote the separation of photoinduced electrons and holes in this triphase photocatalyst system, thereby efficiently boost the photocatalytic hydrogen production activity.
In consideration of the urgency to replace fossil fuel-based energy sources with renewable sources, one should do much to develop efficient photocatalyst that are capable of converting solar energy ...into hydrogen fuel. This work describes the atomic layer deposition (ALD) of ZnO on electrospinning TiO.sub.2 nanofibers to form a 1D TiO.sub.2@ZnO heterojunction. The obtained TiO.sub.2@ZnO composite were systematically investigated to reveal their structural and morphological properties by using SEM, BET, XRD, and TEM with EDX spectroscopy. The TiO.sub.2@ZnO hybrids showed enhanced photocatalytic activity towards hydrogen production as compared to the pure TiO.sub.2 nanofibers. The optimum hydrogen production rate was reaching to 1190.9 mumol/h.sup./g without use of any co-catalytic noble metals, which is 6.5 folds higher than that of bare TiO.sub.2 counterpart, and also better or comparable to the ever reported TiO.sub.2@ZnO photocatalysts. Based on the mechanism analysis, the Type-II heterojunction charge transfer route was responsible for the boosted performance over the TiO.sub.2@ZnO composite.
Attapulgite is a layered silicate with good friction-reduction and self-repairing properties. In order to further improve its tribological properties, the present work mainly focuses on the ...preparation of attapulgite/La
2
O
3
nanocomposite and study on its tribological behaviors. The tribological properties of mineral lubricating oil (150SN) containing attapulgite/La
2
O
3
nanocomposite were investigated through an Optimal SRV-IV oscillating friction and wear tester. The rubbing surfaces and generated tribofilms were characterized by SEM, EDS, XPS and nanoindentation. Results indicated that the friction-reducing ability and antiwear property of the oil were both remarkably improved by attapulgite/La
2
O
3
nanocomposite. A tribofilm mainly composed of Fe, Fe
3
C, FeO, Fe
2
O
3
, FeOOH, SiO, SiO
2
and organic compound was formed on the rubbing surface under the lubrication of oil with attapulgite/La
2
O
3
nanocomposite. The tribofilm possess excellent self-lubricating ability and mechanical properties, which is responsible for the reduction of friction and wear.
Attapulgite is a layered silicate with good friction-reduction and self-repairing properties.
In present study, phenosafranin (PSF) was employed to achieve the dispersion of graphene in water owing to the presence of π-π interaction which was also confirmed from the absorption free energy ...calculated by first principles based on density functional theory. In addition, water-borne epoxy (WEP) coatings containing graphene, PSF and PSF@G were prepared and fabricated on the electrodes. Meanwhile, the corrosion protection performance of different coatings during the immersion in 3.5 wt% NaCl solution was investigated and compared. It could be concluded from the results that PSF@G/WEP coating presented better protective performance than other coatings since the well dispersed graphene in WEP provided superior impermeability to corrosive medium. Besides, the PSF surfactant used to disperse graphene was also beneficial to improve the protective performance of the WEP coating.
Attapulgite is a layered silicate with good friction-reduction and self-repairing properties. In order to further improve its tribological properties, the present work mainly focuses on the ...preparation of attapulgite/La
O
nanocomposite and study on its tribological behaviors. The tribological properties of mineral lubricating oil (150SN) containing attapulgite/La
O
nanocomposite were investigated through an Optimal SRV-IV oscillating friction and wear tester. The rubbing surfaces and generated tribofilms were characterized by SEM, EDS, XPS and nanoindentation. Results indicated that the friction-reducing ability and antiwear property of the oil were both remarkably improved by attapulgite/La
O
nanocomposite. A tribofilm mainly composed of Fe, Fe
C, FeO, Fe
O
, FeOOH, SiO, SiO
and organic compound was formed on the rubbing surface under the lubrication of oil with attapulgite/La
O
nanocomposite. The tribofilm possess excellent self-lubricating ability and mechanical properties, which is responsible for the reduction of friction and wear.
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