Superhydrophobic surfaces based on aluminium oxide coatings had been developed on glass substrates via solution based approach for solar panel cover glass applications. The fabricated surface was ...amorphous with an interconnected porous network of nanoflakes. The static contact angle of the prepared coatings was 161° and exhibited superior self–cleaning behaviour at a tilting angle less than 10°. The 300nm thick coating with refractive index value gradually decreased from air (n −1), through the fabricated coating (n −1.35) towards the glass substrate (n – 1.56) enabled it to acquire a high average transmittance of 95% with anti-reflecting property. The photovoltaic performance of commercially available solar cells covered with uncoated glass substrate and aluminium oxide coated glass substrate was measured under various conditions (such as – fabricated, artificially contaminated and self – cleaned conditions) and the results were compared. The uncoated glass substrate and aluminium oxide coated superhydrophobic glass substrate recovered the efficiency of saw dust contaminated solar panel by 67% and 91%, respectively, thereby enabling the fabricated superhydrophobic glass substrate to be effectively useful for self–cleaning cover glass applications.
•Transparent, anti-reflective and superhydrophobic aluminium oxide coatings were fabricated by chemical method.•The coatings were superhydrophobic with static water contact angle of 155°.•The fabricated superhydrophobic substrates were optically transparent.•The coated glass recovered the efficiency of contaminated solar panel by 91% and useful for cover glass applications.
The poor antiwear properties of Ti–6Al–4V have restricted its applications as biomedical materials. In this work, microgrooves with different groove width and graphene oxide (GO) coating were ...constructed on the surface of Ti–6Al–4V by laser processing and chemical assembly, respectively. The effects of microgroove width on the anticorrosion and biotribological properties of GOs-coated Ti–6Al–4V alloys were systematically investigated. The results indicate that the GOs-coated sample with 45 μm groove width (Ti-45-GO) can effectively improve the anticorrosion of Ti–6Al–4V, due to the surface microstructure homogenization from Ti−45 substrate and the shielding effect of GO coatings. Furthermore, the Ti-45-GO sample exhibits excellent antiwear properties, owing to the capture of wear debris of microgrooves and the high strength and resilience from GO coatings.
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•GOs-coated laser microgrooved Ti–6Al–4V with different groove width are prepared.•The effects of groove width on anticorrosion and antiwear of Ti–6Al–4V are studied.•Groove width of 45 μm can better enhance anticorrosion and antiwear of Ti–6Al–4V.•The anticorrosion and biotribological mechanisms were both discussed.•The treatment can be used to improve anticorrosion and antiwear of other materials.
Abstract
Perovskite solar cells (PSCs) have reached an impressive efficiency over 23%. One of its promising characteristics is the low-cost solution printability, especially for flexible solar cells. ...However, printing large area uniform electron transport layers on rough and soft plastic substrates without hysteresis is still a great challenge. Herein, we demonstrate slot-die printed high quality tin oxide films for high efficiency flexible PSCs. The inherent hysteresis induced by the tin oxide layer is suppressed using a universal potassium interfacial passivation strategy regardless of fabricating methods. Results show that the potassium cations, not the anions, facilitate the growth of perovskite grains, passivate the interface, and contribute to the enhanced efficiency and stability. The small size flexible PSCs achieve a high efficiency of 17.18% and large size (5 × 6 cm
2
) flexible modules obtain an efficiency over 15%. This passivation strategy has shown great promise for pursuing high performance large area flexible PSCs.
An actuator driven by moisture gradients has been developed from a homogeneous graphene oxide film, relying on the in situ formation of a bilayer structure induced by water adsorption. This actuator ...shows efficient and controllable bending motions, coupled with the capability of lifting objects 8 times heavier than itself.
Model systems are very important to identify the working principles of real catalysts, and to develop concepts that can be used in the design of new catalytic materials. In this review we report ...examples of the use of model systems to better understand and control the occurrence of charge transfer at the interface between supported metal nanoparticles and oxide surfaces. In the first part of this article we concentrate on the nature of the support, and on the basic difference in metal/oxide bonding going from a wide-gap non-reducible oxide material to reducible oxide semiconductors. The roles of oxide nanostructuring, bulk and surface defectiveness, and doping with hetero-atoms are also addressed, as they are all aspects that severely affect the metal/oxide interaction. Particular attention is given to the experimental measures of the occurrence of charge transfer at the metal/oxide interface. In this respect, systems based on oxide ultrathin films are particularly important as they allow the use of scanning probe spectroscopies which, often in combination with other measurements and with first principles theoretical simulations, allow full characterization of small supported nanoparticles and their charge state. In a few selected cases, a precise count of the electrons transferred between the oxide and the supported nanoparticle has been possible. Charge transfer can occur through thin, two-dimensional oxide layers also thanks to their structural flexibility. The flow of charge through the oxide film and the formation of charged adsorbates are accompanied in fact by a substantial polaronic relaxation of the film surface which can be rationalized based on electrostatic arguments. In the final part of this review the relationships between model systems and real catalysts are addressed by discussing some examples of how lessons learned from model systems have helped in rationalizing the behavior of real catalysts under working conditions.
Model systems are very important to identify the working principles of real catalysts, and to develop concepts that can be used in the design of new catalytic materials.
Untethered small actuators have various applications in multiple fields. However, existing small-scale actuators are very limited in their intractability with their surroundings, respond to only a ...single type of stimulus and are unable to achieve programmable structural changes under different stimuli. Here, we present a multiresponsive patternable actuator that can respond to humidity, temperature and light, via programmable structural changes. This capability is uniquely achieved by a fast and facile method that was used to fabricate a smart actuator with precise patterning on a graphene oxide film by hydrogel microstamping. The programmable actuator can mimic the claw of a hawk to grab a block, crawl like an inchworm, and twine around and grab the rachis of a flower based on their geometry. Similar to the large- and small-scale robots that are used to study locomotion mechanics, these small-scale actuators can be employed to study movement and biological and living organisms.
In recent years, selective laser melting (SLM)-NiTi alloy has attracted widespread interest due to its ability to prepare medical implant materials with complex shapes and high dimensional accuracy. ...However, SLM-NiTi biomedical materials still face the problems of Ni ion release, poor corrosion performance, and biological inertness. This study is the first to report that the preparation of graphene oxide (GO) coatings on the SLM-NiTi alloy via the electrodeposition method. By changing the deposition time, the effect on coating morphology, corrosion resistance, biomineralization, and biocompatibility was studied. The result showed that GO coating could effectively enhance the corrosion resistance of SLM-NiTi alloy and inhibit the Ni ions release. The GO coating obtained when the deposition time was 20 min possessed the best corrosion resistance, which corrosion current density was about two orders of magnitude lower than that of SLM-NiTi alloy. Moreover, GO coating can effectively promote the adhesion, growth, and proliferation of osteoblasts. Therefore, the GO coated SLM-NiTi alloy is promising for clinical application.
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•GO coatings with different deposition times were fabricated on SLM-NiTi alloy by the electrodeposition method for the first time.•GO coatings significantly enhanced the corrosion resistance of the SLM-NiTi alloy and inhibited the release of Ni ions.•GO coating effectively promoted the adhesion, growth, and proliferation of osteoblasts.
Lithium metal is the ideal anode for the next generation of high-energy-density batteries. Nevertheless, dendrite growth, side reactions and infinite relative volume change have prevented it from ...practical applications. Here, we demonstrate a promising metallic lithium anode design by infusing molten lithium into a polymeric matrix. The electrospun polyimide employed is stable against highly reactive molten lithium and, via a conformal layer of zinc oxide coating to render the surface lithiophilic, molten lithium can be drawn into the matrix, affording a nano-porous lithium electrode. Importantly, the polymeric backbone enables uniform lithium stripping/plating, which successfully confines lithium within the matrix, realizing minimum volume change and effective dendrite suppression. The porous electrode reduces the effective current density; thus, flat voltage profiles and stable cycling of more than 100 cycles is achieved even at a high current density of 5 mA cm(-2) in both carbonate and ether electrolyte. The advantages of the porous, polymeric matrix provide important insights into the design principles of lithium metal anodes.
•RF sputtered chromium oxide coatings were tested in saline solution at a temperature range 25 to 65° C.•The prepared coatings were confirmed to be mainly chromium (III) oxide.•The passive oxide ...layers on the coatings possess p-type semiconductor property.•The acceptor defect densities and corrosion of the coatings were found to be temperature dependent.•Coatings tested at lower temperatures showed superior pitting corrosion resistance compared to those tested at higher temperatures.
The corrosion behaviour of chromium oxide coatings and semiconducting properties of the passive film formed on the surface of the coated samples when exposed to saline solution at a temperature range 25 °C–65 °C was investigated. The cyclic polarisation results revealed that the coatings tested at a electrolyte temperature range 25 °C–35 °C possess superior resistance to pitting corrosion when compared to coatings tested at higher temperatures. Our Mott-Schottky analysis suggests that this variation in corrosion resistance can be linked to the increase in the amount of the defect density present in the films and enhanced diffusion at higher temperatures.
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