Superior shear-stable slippery surface of porous carbon nanospheres (PCN)-oleogel

Abstract

Frictional drag reduction (DR) is of great importance in marine environments as it has the potential to significantly reduce fuel consumption, leading to both economic and environmental benefits. While various conventional DR techniques exist, many of them are energy-inefficient and require external intervention to function effectively in real marine conditions. Unlike conventional methods, bioinspired surfaces offer cost-effective and sustainable DR. However, these surfaces suffer from (i) poor durability of superhydrophobic surfaces, (ii) limited scalability, (iii) substrate dependency of coatings, and (iv) fast depletion of impregnated lubricant oil of liquid infused surfaces (LIS). In this work, we proposed a double-layered LIS oleogel surface embedded with re-entrant surface (RES) morphology by adopting spin/spray-assisted deposition processes. The RES structure, achieved by depositing porous carbon nanospheres (PCN) on the oleogel surface, effectively stabilized and replenished a large amount of lubricated oil, ensuring long-lasting lubrication. The developed PCN-oleogel surface could retain its slippery property despite exposure to harsh physical abrasion, and various chemically contaminated aqueous solutions. The developed PCN-oleogel exhibited long-term lubrication performance and shear-stable durability under high-speed, high-pressure conditions up to 15 ms−1 — such shear-stable lubrication in extremely rare in literature. Conclusively, the proposed PCN-oleogel surface is envisioned to have a great potential in achieving sustainable underwater DR in harsh marine environments.