High-temperature radiative cooling is essential for solar absorbers, as it mitigates efficiency degradation resulting from thermal accumulation. While porous structures have proven effective in enhancing absorber performance, practical manufacturing processes and prolonged operational wear inevitably introduce surface roughness and structural deviations, which profoundly impact radiative properties. This study constructs a ZnS/Ag solar absorber model with surface roughness and employs the finite-difference time-domain method to investigate how characteristic length, surface roughness, porosity, pore shape factor, and taper influence its radiative properties in the 3 μm–5 μm band at 750 K. Results show optimal absorption at a 1 μm characteristic length with a 36.72% improvement compared to the model with l = 0.25 μm, increased absorption with higher porosity with a 69.29% improvement at 0.6 compared to the non-porous structure, lower circularity with a 19.03% improvement for C = 0.89 compared to C = 1.00, while surface roughness with a 61.24% improvement at RMS = 0.031 compared to RMS = 0 and taper with a 38.29% improvement at β = 20° compared to β = 0° also exert significant effects. This work provides engineering design guidelines for high-efficiency, low-cost absorbers.

Thermosensitive hydrogel can integrate vapor molecular capture, in-situ liquefaction, and thermal-induced water release for freshwater capture. This study aimed to examine the dynamic behavior of poly (N-isopropylacrylamide) (PNIPAM) single chain and cross-linking thermosensitive hydrogel through molecular dynamics simulation. Specifically, the impact of lower critical solution temperature (LCST) on the conformation of polymer chain and the interaction between water and polymer chain were also investigated. The polymer chain conformation underwent a transition from coil to globule when the temperature exceeded the LCST, indicating the temperature responsiveness of PNIPAM. Additionally, thermosensitive hydrogel samples with different cross-linking degrees (DOC) were studied, and relevant parameters such as the number of free water, the diffusion coefficient of water, and the pore size distribution were counted to evaluate the temperature responsiveness and water release characteristics of thermosensitive hydrogel.

The self-driven behavior of droplets on a functionalized surface, coupled with wetting gradient and wedge patterns, is systematically investigated using molecular dynamics (MD) simulations. The effects of key factors, including wedge angle, wettability, and wetting gradient, on the droplet self-driving effect is revealed from the nanoscale. Results indicate that the maximum velocity of droplets on hydrophobic wedge-shaped surfaces increases with the wedge angle, accompanied by a rapid attenuation of driving force; however, the average velocity decreases with the increased wedge angle. Conversely, droplet movement on hydrophilic wedge-shaped surfaces follows the opposite trend, particularly in terms of average velocity compared to the hydrophobic case. Both wedge-shaped and composite gradient wedge-shaped surfaces are found to induce droplet motion, with droplets exhibiting higher speeds and distances on hydrophobic surfaces compared to hydrophilic surfaces, regardless of surface type. Importantly, the inclusion of wettability gradients significantly influences droplet motion, with hydrophobic composite gradient wedge-shaped surfaces showing considerable improvements in droplet speed and distance compared to their hydrophilic counterparts. By combining suitable wettability gradients with wedge-shaped surfaces, the limitations inherent in the wettability gradient range and wedge-shaped configuration can be mitigated, thereby enhancing droplet speed and distance. The findings presented in this paper offer valuable insights for the design of advanced functional surfaces tailored for manipulating droplets in real-world applications.