The investigation of the fluorescence mechanism of carbon dots (CDs) has attracted significant attention, particularly the role of the oxygen-containing groups. Dual-CDs exhibiting blue and green emissions are synthesized from glucose via a simple ultrasonic treatment, and the oxidation degree of the CDs is softly modified through a slow natural oxidation approach, which is in stark contrast to that aggressively altering CDs’ surface configurations through chemical oxidation methods. It is interesting to find that the intensity of the blue fluorescence gradually increases, eventually becoming the dominant emission after prolonging the oxidation periods, with the quantum yield (QY) of the CDs being enhanced from ~0.61% to ~4.26%. Combining the microstructure characterizations, optical measurements, and ultrafiltration experiments, we hypothesize that the blue emission could be ascribed to the surface states induced by the C–O and C=O groups, while the green luminescence may originate from the deep energy levels associated with the O–C=O groups. The distinct emission states and energy distributions could result in the blue and the green luminescence exhibiting distinct excitation and emission behaviors. Our findings could provide new insights into the fluorescence mechanism of CDs.

Phosphorus (P) and Boron (B) co-doping effects at the nanoscale in Si nanocrystals/SiO₂ multilayers have been studied in the present work. Several interesting experimental results are achieved which are in contrast to the case in bulk-Si and the previous observations on the doped Si nanocrystals. It is found that all the co-doping samples are n-type regardless of B doping ratios. The P doping efficiency in Si NCs is higher than B dopants, and it can be improved via B co-doping with suitable levels. Raman and ESR spectra indicate that the different occupation preferences of P and B in Si NCs are responsible for the interesting co-doping behaviors. It looks like that the electronic structures and the physical properties of Si NCs can be modulated via the impurities co-doping approach.

Aqueous rechargeable zinc (Zn)–air batteries have recently attracted extensive research interest due to their low cost, environmental benignity, safety, and high energy density. However, the sluggish kinetics of oxygen (O₂) evolution reaction (OER) and the oxygen reduction reaction (ORR) of cathode catalysts in the batteries result in the high over-potential that impedes the practical application of Zn–air batteries. Here, we report a stable rechargeable aqueous Zn–air battery by use of a heterogeneous two-dimensional molybdenum sulfide (2D MoS₂) cathode catalyst that consists of a heterogeneous interface and defects-embedded active edge sites. Compared to commercial Pt/C-RuO₂, the low cost MoS₂ cathode catalyst shows decent oxygen evolution and acceptable oxygen reduction catalytic activity. The assembled aqueous Zn–air battery using hybrid MoS₂ catalysts demonstrates a specific capacity of 330 mAh g⁻¹ and a durability of 500 cycles (~180 h) at 0.5 mA cm⁻². In particular, the hybrid MoS₂ catalysts outperform commercial Pt/C in the practically meaningful high-current region (>5 mA cm⁻²). This work paves the way for research on improving the performance of aqueous Zn–air batteries by constructing their own heterogeneous surfaces or interfaces instead of constructing bifunctional catalysts by compounding other materials.

A new idea was provided by the group-IV GeSn alloys for short-wave infrared light source compatible with CMOS due to the low cost integrated on the Si platform and can be transformed into direct bandgap alloy. More than 7.1% Sn content or strain engineering is used to achieve the direct bandgap GeSn semiconductors and enhance the luminous efficiency of GeSn light-emitting devices. We theoretically investigate a strain-adjustable GeSn light-emitting diode with the giant magnetostrictive stressor. A 0 ∼ 0.11% adjustable uniaxial tensile strain is introduced into Ge _0.92 Sn _0.08 LED by adjusting the external magnetic field. A continuously adjustable bandgap from 0.543 eV to 0.475 eV of the Ge _0.92 Sn _0.08 alloy is achieved in the magnetic field intensity range of 0 ∼ 240 kA/m, and the spontaneous emission rate of the strained LED is enhanced about 3.63 times compared with the relaxed device. Besides, an adjustable range of luminous peak is achieved from 2.18 μm to 2.46 μm, which can promote the application of GeSn light source for magnetic field detection and photo-communication in short-wave infrared.

In this paper, a physical model is established to reveal the relationship between polarization phase of incident light and in-plane spin splitting (IPSS) of reflected beam, and the impact of polarization phase on the IPSS is systematically investigated. Three interesting features of the effect of polarization phase on IPSS were discovered. Furthermore, it is found that the IPSS can be effectively enhanced and suppressed by adjusting the polarization phase near /2. The enhanced IPSS shift can almost reach its upper limit (that is, half of the beam waist) and the suppressed IPSS shift can be reduced to zero. In addition, it is also found that the spin cumulative direction of spin components can be reversed adjusting the polarization phase at /2. These findings not only provide a deeper insight into photonic spin Hall effect, but also open a path for the photon manipulation, precision metrology and the manufacture of photonic spin switching devices.

The plasticity of GeSn alloy energy band has promoted the development of silicon-based photoelectric integration and optical interconnection. A tensile-strained GeSn/SiGeSn double heterostructure laser wrapped with Si₃N₄ stress liner is designed and characterized theoretically. The triaxial tensile strain is introduced into the GeSn/SiGeSn heterostructure laser by the Si₃N₄ linear stressor. The lower threshold current density and higher optical gain of the GeSn/SiGeSn laser can be achieved by tuning the band structure and carrier distribution in the active region with tensile strain and Sn compositions. Compared with the relaxed device, the value of n_{e ,Γ}/n_{e ,total} for the Ge_0.90Sn_0.10/Si_0.315Ge_0.499Sn_0.186 heterostructure laser wrapped with 300 nm Si₃N₄ linear stressor is increased to 30.6% at n _e,total of 10¹⁸ cm⁻³, the laser λ can be extended to 3.44 μm, and the J _th is reduced from 206 to 59 A/cm².