Superhydrophobic surfaces, characterized by water contact angles greater than 150°, have attracted widespread interest due to their exceptional water repellency and multifunctional applications. However, traditional fabrication methods often rely on fluorinated compounds and petroleum-based polymers, raising environmental and health concerns. In response to growing environmental and health problems, recent research has increasingly focused on developing green superhydrophobic surfaces, employing eco-friendly materials, energy-efficient processes, and non-toxic modifiers. This review systematically summarizes recent progress in the development of green superhydrophobic materials, focusing on the use of natural substrates such as cellulose, chitosan, starch, lignin, and silk fibroin. Sustainable fabrication techniques, including spray coating, dip coating, sol–gel processing, electrospinning, laser texturing, and self-assembly, are critically discussed with regards to their environmental compatibility, scalability, and integration with biodegradable components. Furthermore, the functional performance of these coatings is explored in diverse application fields, including self-cleaning, oil–water separation, anti-corrosion, anti-icing, food packaging, and biomedical devices. Key challenges such as mechanical durability, substrate adhesion, and large-scale processing are addressed, alongside emerging strategies that combine green chemistry with surface engineering. This review provides a comprehensive perspective on the design and deployment of eco-friendly superhydrophobic surfaces, aiming to accelerate their practical implementation across sustainable technologies.

Nanocomposites have attracted significant attention as lubricant additives due to their advantages in reducing friction, enhancing wear resistance, and improving thermal and oxidative stability. In recent years, increasing research has explored how different types of nanomaterials (such as carbon-based materials, metallic nanoparticles, and ceramic phases) can use synergistic effects to achieve performance surpassing that of their single components. This review focuses on relevant studies published between 2020 and 2025, providing an updated overview of the advantages, synthesis methods, structures, dispersion stability, lubrication mechanisms, and tribological behavior of nanocomposites. Various structural types are discussed, including core-shell, layered, and in-situ hybrid systems, along with their fabrication routes such as sol-gel processing, hydrothermal synthesis, and surface modification strategies. The lubrication mechanism of nanocomposites is analyzed based on the material structure and the testing conditions. Particular attention is paid to the synergistic effects among multiple components within the nanocomposites and how these synergies enhance tribological performance. Furthermore, the challenges faced by nanocomposites and potential future developments are discussed. This review aims to clarify the current status of nanocomposites as lubricant additives and facilitate their future application in advanced lubrication systems.