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Organic piezoelectric materials exhibit excellent physical properties and potential applications in implantable biological devices. As a result flexible nanoscale piezoelectric sensors based on these materials have been the focus of numerous investigations. Different strategies have been developed as promising approaches to obtain high properties flexible nano devices. Nevertheless, the piezoelectric performance of the materials could not be fully utilized, which in turn leads to a decrease in the sensitivity of the device. Here, the highly efficient utilization of flexible nanoscale piezoelectric sensor is realized through the ingenious design of the interdigital electrode structure. The high flexibility is attributed to the organic materials of P(VDF-TrFE). The output performance of the sensor made by the nanofibers has been greatly improved, since each segment of the nanofibers on the interdigital electrode structure is utilized efficiently. The results show that a maximum voltage of 140 mV and a current of about 0.59 nA for the sensor are generated. The volume power density of the nano device based on P(VDF-TrFE) nanofibers is 5.01 nW cm−3. This proposed method could be a promising strategy to fabricate future nanoscale piezoelectric sensors. • The P(VDF-TrFE) nanofibers with good surface morphology are obtained by controlling feeding rate of the precursor solution. • A flexible interdigital structure type nano sensor based on P(VDF-TrFE) nanofibers are fabricated. • The piezoelectricity of P(VDF-TrFE) can be effectively utilized by using the interdigital structure type nano sensor. • The delivered power of the sensor can be up to 507 nW with a load resistance of 100 ΩM. [ABSTRACT FROM AUTHOR]

The artificial-photosynthetic semiconductor composites have attracted tremendous attention with respect to their enhanced photocatalytic properties. Herein, we reported the facile synthesis of Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O S-scheme photocatalyst via one-pot in situ hydrothermal strategy. Density Functional Theory (DFT) calculation was employed to reveal the S-scheme photogenerated electron transfer mechanism, and the subsequent experimental characterization further illustrated the path for electron-hole transfer and separation under the effect of S-scheme heterojunction. The mass of WO 3 ·H 2 O accounted for Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O 48 wt% (ZCSW48) was the best high-efficiency S-scheme photocatalyst displayed significant photocatalytic properties on pollution degradation, in detail, with the Cr (VI) photoreduction rate of 2.27 μmol·s−1·g−1 cat. and the Rhodamine B (RhB) photooxidation rate of 0.38 μmol·min−1·g−1 cat. , respectively. The designed Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O photocatalysts have integrated with the three aspects of photocatalytic efficiencies including the visible light response, prolonged photogenerated carrier lifetime and the sufficient surface active sites due to amount of surface defects, therefore, this work provides more insights into the utilization of green energy for environmental treatment by artificial structured semiconductors. [Display omitted] • The facile one-pot hydrothermal method was used to synthesize photocatalyst. • DFT calculation and experiments were used to interpret charge carrier transfer. • The S-scheme photocatalyst possessed bifunctional pollutant degradation application. • A novel photocatalyst highly improves the photogenerated carrier separation efficiency. [ABSTRACT FROM AUTHOR]

Tensile tests over a wide range of strain rates (1.04 × 10 −6 to 1.04 s −1 ) were performed on electrodeposited nanocrystalline (NC) Ni and Ni-Co alloys with different grain sizes to systematically investigate the coupling effects of strain rate and grain size on the mechanical behaviors. It was found that the grain size significantly affected the dependency of mechanical responses to the imposed strain rate. In particular, peculiar fluctuations of flow stress and elongation-to-failure with variation of strain rate were observed in the Ni-8.6 wt%Co alloy with the finest grain size. By carefully analyzing the changes in strain rate sensitivity exponent and apparent activation volume, such unique phenomenon was rationalized in terms of the synergy of grain size and strain rate on the transition of deformation mechanisms including thermal-activated and mechanical-driven grain boundary (GB) activities, interactions of dislocations with GBs and diffusional creep, which act alone or in concert to dominate the plasticity. Building on classifying the characteristics of plastic deformation on the nano-scale, a two dimensional deformation mechanism map was proposed to comprehensively elucidate the interactive effects of grain size and strain rate on the deformation mechanisms and the related mechanical behaviors in face-centered-cubic NC Ni and Ni-based alloys. [ABSTRACT FROM AUTHOR]

The development of transition metal-based materials to replace precious metal electrocatalysts in a facile and efficient approach is of great importance for water splitting. The NiS/MoS 2 complex grown in situ on carbon paper (NiS/MoS 2 /CP) by a one-step hydrothermal method was successfully constructed as an efficient electrocatalyst. The synergetic effects of the superhydrophilic/aerophobic surface, hierarchical nanostructure and strong mechanical adhesion to a highly conductive substrate give the NiS/MoS 2 /CP complex outstanding catalytic activity and durability. Specifically, it exhibits relatively low overpotentials of 119 mV (at a current density of 10 mA cm−2) and 314 mV (at a current density of 100 mA cm−2) for the hydrogen evolution reaction and oxygen evolution reaction, respectively. In addition, the NiS/MoS 2 /CP complex can also be used as an electrolyzer that reaches a current density of 10 mA cm−2 at a cell voltage of 1.48 V without decay after 30 h of durability testing, making it an ideal electrocatalyst for water splitting towards practical application. [Display omitted] • The surface of carbon paper was transformed to be super-hydrophilic/aerophobic via calcination. • NiS/MoS 2 composite is grown in-situ on carbon paper by a facile one-step hydrothermal method. • The NiS/MoS 2 /CP complex exhibits high catalytic activity and excellent durability. [ABSTRACT FROM AUTHOR]

Creep behaviors of nanocrystalline (NC) Cu, Ni-20(wt.%)Fe and Ni with comparable grain sizes were examined by nanoindentation tests. It was showed that the creep behaviors depend on loading strain rate and stacking fault energy (SFE). At high loading strain rate, the initial creep rates of three NC materials are far higher than those predicted by the models of the Coble creep and the grain boundary sliding and are the highest and lowest for NC Cu and NC Ni, respectively, while that of NC Ni–20Fe lies between them due to their different SFE. At low loading strain rate, the creep behaviors do not exhibit significant difference among three NC materials. Our analysis revealed that grain boundary dislocation sources can be activated at high loading strain rate and the emitted dislocations from grain boundaries can be effectively stored in the loading regime, but cannot at low loading strain rate. The very high initial creep rates of three NC materials are attributed to the rapid absorptions of the stored dislocations in the loading regime and the newly nucleated dislocations in the holding regime. The higher creep rate of NC Cu as compared with those of NC Ni–20Fe and NC Ni arises from the higher density of the stored dislocations caused by the enhanced interactions of dislocations with twins and stacking faults due to its lower SFE. [ABSTRACT FROM AUTHOR]

• Single crystals with different orientations were prepared to investigate the corrosion behavior of the Al-Cu alloy. • The corrosion rates of the Al-Cu alloy varied in different crystal orientations. • The corrosion pits of the as-quenched alloy show the geometric shapes corresponding to the crystal orientations. • The corrosion of the aged alloy was propagated in the form of corroded bands that parallel to the {001} Al plane. • The precipitation of θ' phase significantly deteriorated the corrosion resistance of the Al-Cu alloy. Al-Cu single crystals with different typical orientations (i.e., (001), (101), and (111)) were prepared to investigate the corrosion behavior of the Al-Cu alloy with and without precipitates by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion testing in EXCO solution, and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion rates of the alloy with different orientations increased in the order of (111)< (001)< (101) in the solid solution state (without precipitates), while those of the alloy increased in the order of (101)< (001)< (111) in the aged state (with precipitates). The corrosion resistance of the alloy without precipitates was mainly determined by the atomic density of the crystal plane, and that of the alloy with precipitates was mainly provided by the corrosion product film. After aging, the precipitation of the θ' phase led to anodic dissolution of the nearby matrix and further accelerated the corrosion rates of the alloy. Furthermore, the corrosion pits of the alloy without precipitates showed geometric shapes corresponding to the crystal orientations. The corrosion of the alloy with precipitates propagated in the form of corroded bands, which were parallel to the {001} Al plane. [ABSTRACT FROM AUTHOR]

Reducing grain size of materials down to the nanoscale regime usually leads to tremendous increase in strength yet at the expense of other key mechanical properties, including creep resistance. Here we demonstrate that nanostructuring endows a CrMnFeCoNi high-entropy alloy and a CrCoNi medium-entropy alloy with excellent combination of extraordinarily high hardness of 11–13 GPa, which is three times higher than those of their coarse-grained counterparts, and much enhanced creep resistance compared with conventional nanocrystalline metals. Grain boundary strengthening and stacking fault strengthening are the two major reasons responsible for the elevated hardness. The combined influence of low stacking fault energy and small grain sizes enables the prosperity of stacking faults, which also accounts for the higher strength of the ternary alloy than that of the quinary one. Theoretical analysis together with microstructural characterization suggest that the increasing interfacial chemical complexity suppresses grain boundary mediated processes, leading to much improved creep resistance with a dislocation-dominant creep mechanism in the nanocrystalline alloys. Our findings shed light on a new perspective for achieving simultaneous ultra-high strength and considerable structural robustness in structural materials. • Nanocrystalline CrMnFeCoNi HEA and CrCoNi MEA were magnetron sputtered. • Nanostructuring endows both alloys with ultra-high strength of 11–13 GPa. • Grain boundary and stacking fault contribute predominantly to the elevated hardness. • Interfacial chemical complexity leads to much improved creep resistance in both alloys. • Dislocation-dominant creep mechanism prevails in nanocrystalline HEA and MEA. [ABSTRACT FROM AUTHOR]