Taiyuan University of Technology

In this paper, the mech. properties of carbon nanotube reinforced nylon 6 composites were investigated using mol. dynamics simulations.The effects of different types of carbon nanotubes (armchair type and zigzag type) on the mech. properties of the composites were investigated, and it was found that the elastic modulus of the armchair-type carbon nanotube reinforced composites was higher.The effects of carbon nanotube content and temperature on the mech. properties of the composites were investigated, and it was found that the mech. properties of the composites were best at 6.71% carbon nanotube content, and the composites exhibited good thermal stability and the mech. properties at lower temperaturesThe results show that different strain rates have a significant effect on the ultimate stress of the composites, and the mech. properties of the composites are better at high strain rates.Different degrees of functionalization of carbon nanotubes can improve the mech. properties of composites.When the number of carboxyl groups is 8, the mech. properties of the composites are the best, with an ultimate stress of 0.44 GPa and an elastic modulus of 3.64 MPa, which are 19% and 23% higher than that of the unfunctionalized ones, resp.

PbTe is a benchmark mid-temperature material, yet its n-type performance remains constrained by low conduction-band degeneracy, impurity-induced mobility degradation and deleterious interfacial carrier scattering. Here, a solution-processable solvothermal injection strategy is reported to construct Bi-doped PbTe bead-on-a-string nanowires that integrate Bi-induced band-edge reconstruction with ordered couple phonon scattering. Nonclassical nucleation and oriented attachment produced phase-pure polycrystalline nanowires with an aspect ratio of approximately 100, uniform Bi incorporation and near-coherent nanodomains after spark plasma sintering. Density functional theory, optical absorption spectroscopy, femtosecond transient absorption and local-structure analyses revealed that Bi doping introduced resonant features near the band edge, narrowed the optical bandgap from 0.21 to 0.11 eV, accelerated carrier relaxation and reorganized the Pb-Te/Bi coordination environment. In the optimized Pb_0.98Bi_0.02Te, the carrier concentration reached 1.2 × 10¹⁹ cm^-3 while the Hall mobility remained as high as 905 cm² V^-1 s^-1 at 300 K, yielding a peak power factor of 30.2 μW cm^-1 K^-2 at 373 K. Meanwhile, ordered grain boundaries and coherent nanodomains reduce the lattice thermal conductivity to 0.75 W m^-1 K^-1 at 823 K. Consequently, Pb_0.98Bi_0.02Te achieved a peak thermoelectric figure of merit (zT) of approximately 1.3 at 723 K, maintained zT > 1 from 500 to 823 K, and delivered an average zT of 0.59 over 300-623 K. This band-interface co-design strategy provides a generalizable route for coupled optimization in n-type PbTe and offers a solution-processable platform for mid-temperature waste-heat recovery.

Scalable, passive, and round-the-clock atmospheric water harvesting (AWH) remains challenging due to diurnal energy asymmetry and insufficient nighttime driving force. Here, we report a dual-mode synergistic AWH device integrating hemispherical optical design, passive radiative cooling (RC), and phase-change thermal control (TC) to enable uninterrupted day-night water production. The RC layer provides a persistently low-temperature condensation surface with high solar reflectivity (∼0.95) and atmospheric window emissivity (∼0.98). The TC layer stores solar heat during the day and releases latent heat at night to stabilize internal vapor pressure and dew point. Outdoor experiments show the system achieves a water yield of 0.116 kg·m^-2·h^-1, 214% higher than a bare hemispherical AWH, with 1.7× nighttime improvement over an RC-only device. The total condensation efficiency reaches 77.3% of the theoretical limit. After 500 h of accelerated UV aging, both layers retain stable optical and thermal properties. This strategy offers a reliable pathway for off-grid, all-weather freshwater production in mid-to-high latitude and water-scarce regions.