We report on the achievement of wafer-level photocatalytic overall water splitting on GaN nanowires grown by molecular beam epitaxy with the incorporation of Rh/Cr(2)O(3) core-shell nanostructures acting as cocatalysts, through which H(2) evolution is promoted by the noble metal core (Rh) while the water forming back reaction over Rh is effectively prevented by the Cr(2)O(3) shell O(2) diffusion barrier. The decomposition of pure water into H(2) and O(2) by GaN nanowires is confirmed to be a highly stable photocatalytic process, with the turnover number per unit time well exceeding the value of any previously reported GaN powder samples.
Full-color, catalyst-free InGaN/GaN dot-in-a-wire light-emitting diodes (LEDs) were monolithically grown on Si(111) by molecular beam epitaxy, with the emission characteristics controlled by the dot properties in a single epitaxial growth step. With the use of p-type modulation doping in the dot-in-a-wire heterostructures, we have demonstrated the most efficient phosphor-free white LEDs ever reported, which exhibit an internal quantum efficiency of ∼56.8%, nearly unaltered CIE chromaticity coordinates with increasing injection current, and virtually zero efficiency droop at current densities up to ∼640 A/cm(2). The remarkable performance is attributed to the superior three-dimensional carrier confinement provided by the electronically coupled dot-in-a-wire heterostructures, the nearly defect- and strain-free GaN nanowires, and the significantly enhanced hole transport due to the p-type modulation doping.
This paper challenges the prevailing view that investor sentiment is a contrarian predictor of market returns at nearly all horizons. As an important piece of "out-of-sample" evidence, we document that investor sentiment in China is a reliable momentum signal at monthly frequency. The strong momentum predictability is robust under both single- and multi-regressor settings, and is statistically and economically significant both in and out of sample, enhancing portfolio performance as shown by our numerical examples. More importantly, we find a striking term structure that local sentiment shifts from a short-term momentum predictor to a contrarian predictor in the long run. Cross-sectional analysis reveals that sentiment is more of a small-firm effect. Finally, we confirm that global sentiment spills over to the local Chinese market, as it predicts negatively future returns over the longer horizons and in the cross section
BiFeO 3 / Bi 3.15 Nd 0.85 Ti 3 O 12 (BFO/BNdT) multilayer films have been grown on Pt-coated silicon substrate by chemical solution deposition. Using Bi3.15Nd0.85Ti3O12 as an inducing layer, ferroelectric properties of BiFeO3 were enhanced significantly. The 2Pr and coercive electric field of the Pt/BFO/BNdT/Pt capacitor were about 22.1 μC/cm2 and 50 kV/cm, respectively. The dielectric constant and the dissipation factor of the multilayer were 373 and 0.05 measured at 105 Hz, respectively. The multilayer capacitors not only exhibited excellent fatigue resistance without polarization reduction after 1010 switching cycles but also showed lower leakage current density (around the order of 10−9–10−7 A/cm2) and negligible data loss due to imprint. The magnetic hysteresis indicated that the multiplayer was antiferromagnetic and the saturated magnetization was about 2.47 emu/cm3.
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