Joule-heating assisted heliotropic solar steam generator for all-day, all-weather solar desalination

Recently, interfacial solar based desalination has gained large interest as a sustainable solution for global water scarcity. However, the poor water collection rate due to unfavorable weather conditions and unpredictable solar intensity makes it impractical in real operations. In this report, we proposed a novel joule-heating assisted heliotropic solar steam generator for all-day, all-weather solar desalination. For this, hydrophobic carbon fabric (CF) was first functionalized using thiol functionalization (t-CF) and then combined with melamine sponge to obtain t-CF-melamine solar steam generator (SSG). The heating properties of t-CF-melamine are examined, and the surface temperature reaches as high as 155 °C in <5 min at an input voltage of 3 V. Under 1 sun irradiation condition, the evaporation rate of the t-CF-melamine SSG is increased dramatically to 11.2 kg m−2 h−1 at 3 V input voltage. This is attributed to the synergetic effect of photothermal and electrothermal effects of t-CF. Through desalination experiments, the heliotropic design was able to reject salt effectively while maintaining a stable evaporation rate of 11.57 kg m−2 h−1. In addition, t-CF also performed extremely well at low voltage (1–3 V) conditions demonstrating the capability of all-day, all-weather solar desalination. The present results of this work would inspire further research on electrically conductive materials for joule-heating assisted solar steam generation (SSG) devices for practical all-day, all-weather solar desalination.