An anti-salt accumulation 2.5D arch solar-driven evaporator based on Marangoni effect for seawater desalination

• A 2.5D arch solar-driven evaporator for efficient seawater desalination was developed. • It has excellent long-term anti-salt accumulation capacity due to Marangoni effect. • It shows a competitive water evaporation rate of 1.94 kg m -2 h -1. • The evaporation efficiency exceeds the limit of 2D evaporators, reaching 125.6% Solar-driven evaporative seawater desalination is considered as a promising technology to alleviate the global water crisis with minimal carbon footprint. However, the design of evaporators still faces significant challenges, such as complex preparation processes and the tendency of salt accumulation. Here, we propose an anti-salt accumulation 2.5D arch solar-driven evaporator based on the Marangoni effect for efficient seawater desalination. Using a 2D planar, flexible, and mechanically stable copper mesh coated with biomass-derived carbon microspheres, the evaporator is easily shaped into a 2.5D arch, which expands the evaporation area and accelerates the escape of steam, thus increasing the evaporation rate. Importantly, the curvature of the 2.5D arch evaporator can be easily modulated by changing the height-diameter (H/D) ratio, which in turn regulates the temperature gradient along the arch surface, leading to a Marangoni effect for long-term anti-salt accumulation. The optimal 2.5D arch (H/D= 3/4) displays a competitive evaporation rate of 1.94 kg m -2 h -1 and an excellent evaporation efficiency of 125.6% for 3.5 wt% NaCl aqueous solution under one-sun irradiation, as well as long-term anti-salt accumulation performance (3.5 wt% brine for 30 h). This work provides new ideas for the design of efficient, salt-resistant, and environmentally friendly solar-driven evaporators, advancing their practical application in sustainable water production.