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The low sulfur utilization, cycling instability, and sluggish kinetics are the critical obstructions to practical applications of lithium-sulfur batteries (LSBs). Constructing sulfur hosts with high conductivity, suppressed shuttle effect, and rapid kinetics is essential for their practical application in LSBs. Here, we synthetically utilized the merits of ZnSe quantum dots (QDs) and layered Ni(OH)2to boost the performance of LSBs. A novel core-shell ZnSe-CNTs/S@Ni(OH)2was constructed using the ZnSe-CNTs network as framework to load sulfur and following with Ni(OH)2encapsulation. The CNT network decorated with ZnSe QDs not only serves as a conductive framework providing fast electron/ion transfer channels, but also limits polysulfide diffusion physically and chemically. Layered Ni(OH)2, the wrinkled encapsulation, not only permits fast electron/ion transfer, but also buffers the expansion, confines active materials, and limits the polysulfide dissolution chemically. When used as a cathode, ZnSe-CNTs/S@Ni(OH)2presents enhanced electrochemistry performance compared with ZnSe-CNTs/S and CNTs/S. The average specific capacity decreases from 1021.9 mAh g-1at 0.2 C to 665.0 mAh g-1at 2 C, showing rate capacity much higher than ZnSe-CNTs/S and CNTs/S. After 150 cycles, the capacity at 0.5 C slowly reduces from 926.7 to 789.0 mAh g-1, showing high retention of 85.1%. Therefore, our investigation provides a new strategy to construct a promising sulfur cathode for LSBs.

The optical properties of the type-II lineup In x Al1−x N–Al0.59Ga0.41N/Al0.74Ga0.26N quantum well (QW) structures with different In contents are investigated by using the six-by-six K–P method. The type-II lineup structures exhibit the larger product of Fermi–Dirac distribution functions of electron f c n and hole ( 1 − f v U m ) and the approximately equal transverse electric (TE) polarization optical matrix elements ( | M x | 2 ) for the c1–v1 transition. As a result, the peak intensity in the TE polarization spontaneous emission spectrum is improved by 47.45%–53.84% as compared to that of the conventional AlGaN QW structure. In addition, the type-II QW structure with x ∼ 0.17 has the largest TE mode peak intensity in the investigated In-content range of 0.13–0.23. It can be attributed to the combined effect of | M x | 2 and f c n ( 1 − f v U m ) for the c1–v1, c1–v2, and c1–v3 transitions.

The collision of a single-walled carbon nanotube (SWCNT) with two graphitic patches has been simulated by the tight-binding molecular dynamics method. We found that it is possible that a close-ended SWCNT with a large diameter can be formed by this kind of collision. This is a possible route in which a SWCNT with a small radius can convert into a SWCNT with a larger radius.

Temperature dependence of the optical properties of InGaN/GaN single quantum well light-emitting diodes (LEDs) with different indium (In) contents is investigated by using the effective mass theory taking into account the band-gap shrinkage and lattice thermal expansion. The peak intensity of the spontaneous emission spectrum is decreased by 30.6%, 30.4%, and 30.3% for the violet, blue, and green LEDs in the temperature range 300 K?400?K, while the reductions of internal quantum efficiency (?) with temperature are ~0.13, ~0.11, and ~0.1 respectively at the injection current density of 100 A cm?2. Moreover, two different slopes for all the ??T curves are observed: a lower absolute value of the slopes at T??=??300?350?K; a larger absolute value of the slopes at T??=??350?400?K. The numerical results also indicate that the efficiency droop effect with increasing the temperature becomes more serious, especially for the InGaN/GaN LED structures with the lower In-content.

Cu2O–TiO2–ZnO ternary nano-heteroarchitectures were designed and successfully fabricated using titanium (IV) oxideacetylacetonate (TiO(acac)2) as a precursor and polyethyleneimine (PEI) as a binding agent. Field emission and photocatalytic activities of pure Cu2O nanopines, Cu2O–TiO2 core–shell nanopines and Cu2O–TiO2–ZnO ternary composites were investigated and compared. The results revealed that the as-prepared nano-heterojunctions and nanoparticles at the surface remarkably enhanced the field emission and photocatalytic activities of pure Cu2O nanopines. The as-prepared nano-heterojunctions induced interfacial states and energy band differentials, which caused electron transition and the inhibition of photo-induced electron–hole pair recombination. The nanoparticles at the surface formed thousands of surface nano-protrusions and active sites for photocatalytic chemical reactions.