Cellulose aerogel evaporators with vertical channels inspired by lotus rods for highly efficient solar water evaporation

Designing and developing solar absorbers is essential for achieving high solar-to-vapor energy conversion efficiency and evaporation rate. Currently, evaporators with vertical channels have been developed to improve evaporation efficiency and salt tolerance, but high preparation and complex process limit their practical application. Herein, a cellulose aerogel evaporator with a vertical channel structure was fabricated using simple directional freezing technology. The evaporator exhibited outstanding light absorption capabilities across a spectrum of 250–2500 nm. Importantly, the exceptional hydrophilicity of cellulose and the synergistic effect of vertical channels facilitated water transport, thereby enhancing evaporation efficiency. When exposed to one sun irradiation (1 kW m−2), the cellulose aerogel evaporator achieved an evaporation rate of 1.80 kg m−2 h−1. Moreover, the evaporator can automatically discharge salt through convection and diffusion to ensure its long-term operation, and no salt accumulation is found on the surface of the evaporator during the evaporation cycles. This work introduces a straightforward, cost-effective, and easily deployable solar evaporator in which the presence of vertical channels provides technical support for the realization of efficient and sustainable solar seawater evaporation technology.