Polyaryletherketone polymer nanocomposite engineered with nanolaminated Ti3SiC2 ceramic fillers

Thermal, mechanical and tribological properties of a new ceramic–polymer nanocomposite in which polyaryletherketone (PAEK) polymer was reinforced with titanium silicon carbide (Ti₃SiC₂), a ceramic nanolaminate belonging to the MAX phase family (M is an early transition metal, A represents group IIIA or IVA element and X is either carbon and/or nitrogen) are reported for the first time. PAEK–Ti₃SiC₂ nanocomposites with varying volume fractions of Ti₃SiC₂ were processed by hot pressing. The effect of Ti₃SiC₂ on the thermal expansion, bulk hardness, mechanical strength, wear and friction properties was systematically analyzed and the results are discussed. The study confirms that the Ti₃SiC₂ controlled the high thermal expansion property of PAEK polymer. In addition to that, it enhanced the wear resistance and mechanical strength of PAEK without affecting its inherent low-friction characteristics.     

Photoelectrochemical hydrogen production at peak efficiency over 10% via PbSe QDs/TiO2 nanotube array photoanodes

Modulating the deposition of quantum dots onto TiO₂ nanotube arrays provides an effective approach for expansion of visible light response, enhancement of separation and interfacial transfer of photoinduced charge carries, and improvement of photoconversion efficiency. In this paper, titanium dioxide nanotube arrays (TNAs) were modified with PbSe quantum dots (QDs) through the successive ionic layer adsorption and reaction (SILAR) under nitrogen to prepare PbSe/TNAs photoanodes. XRD, SEM, HR-TEM, UV–Vis–NIR DRS, PL, XPS, EIS, Tafel plots, Mott–Schottky analyses and J–V characteristics were used to characterize the samples. The deposition of PbSe QDs was tuned by varying the Se/Pb atomic ratios during the SILAR process. Energy band configuration, interfacial contact characteristics and photoelectrochemical properties were dissected and optimized. At the Se/Pb ratio of 5, the sample (5)PbSe/TNAs demonstrated excellent photoelectrochemical performance with a short circuit photocurrent density of 15.45 mA cm^?2 and a corresponding photoconversion efficiency of 10.6%.     

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively.     

Discharge cutting technology for specific crystallographic planes of monocrystalline silicon

Crystallographic planes were detected with X-ray crystal orientation instrument to study wire-cut electrical discharge machining (WEDM) technology for specific crystallographic planes of monocrystalline silicon. The unidirectional conductivity of monocrystalline silicon was analyzed. The contact potential barrier was decreased by preparing Ohmic contact to the surface discharging of the input terminal. Finally, the high-precision discharge cutting of the specific crystallographic planes of monocrystalline silicon was validated. Finished silicon products with specific crystallographic planes were prepared by WEDM, and the cutting efficiency, surface quality, crystal orientation precision, and qualified rate were determined. With cutting thickness of 200 mm, the cutting efficiency reached 100 mm²/min, and the precision of crystal orientation reached 3′ or less.     

Proton Conduction in Dense and Porous Nanocrystalline Ceria Thin Films

The electrical conductivity of ceria thin films (epitaxial as well as dense and porous nanocrystalline) is investigated in dry and wet atmosphere at temperatures below 500 °C. For the epitaxial and the fully dense nanocrystalline samples, no significant differences can be observed between dry and wet conditions. In marked contrast, the nanocrystalline porous films obtained via spin coating exhibit a considerable enhancement of the protonic conductivity below 300 °C in wet atmosphere. This outcome reveals that the residual open mesoporosity plays the key role for the enhancement of the proton transport at low temperatures and not the high density of grain boundaries. The quantitative analysis of the various pathways, along which the proton transport can take place, indicates that the observed proton conduction can arise not only from bulk water adsorbed in the open pores but also from the space charge zones on the water side of the water/oxide interface.     

Efficient and robust visible light photocatalytic H2 production based on CdSe quantum dots sensitized titania

In this work, cadmium selenide quantum dots (CdSe QDs) with different sizes were synthesized and employed as visible light sensitizers of titania, in comparison with other organic molecules based sensitizers, including the well-known ruthenium complex sensitizer, tris(4,4-dicarboxy-2,2-bipyridyl)ruthenium(II) chloride, phenolic-formaldehyde resin and poly (4-vinylphenol). The different sensitizers are linked to titania via different molecular linkages through self-assemble processes. CdSe QDs adsorbed onto titania via stabilization ligand (mercaptopropionic acid) are more stable and efficient in terms of photocatalytic H₂ generation and photocurrent generation. The CdSe QDs with a diameter of 2.5 nm exhibits a strong absorption peak centred at 500 nm (CdSe500) and shows the best photocatalytic performance than other QDs with larger size and organic sensitizers. The turnover number of CdSe500 QDs for H₂ generation reaches ca. 9000 after 96 h reaction, with a 0.6% quantum yield under irradiation at 450 nm (light intensity = 35 mW/cm²). During the initial 3.0 h reaction, the turnover numbers of different types of sensitizers are estimated about 4.3, 52.5, 323.2 and 16.5 for phenolic-formaldehyde resin, poly (4-vinylphenol), CdSe500 QDs and ruthenium complex, respectively. These results highlights the advantages of utilizing CdSe QDs as stable visible light sensitizers for solar energy conversion.