Multifunctional Chinese ink-coated viscose fiber composite for evaporation-driven electricity generation and solar-driven steam generation

Technologies for evaporation-driven electricity generation and solar-driven steam generation exhibit significant potential for addressing energy crises and freshwater shortages. Nevertheless, it is still a challenge to develop multifunctional materials for efficient energy generation and seawater desalination via economical and simple methods. Here, we propose a Chinese ink-coated viscose fiber composite (Ink@VF), suitable for direct applications in evaporation-driven electricity generators (EEGs) and solar-driven steam generators (SSGs). The Ink@VF prepared by a simple dip-dyeing method exhibits excellent mechanical properties (Young's modulus of 18.1 GPa), hydrophilicity, electrical conductivity (36.51 Ω/sq), and photothermal conversion properties. Based on the synergy of water evaporation, capillary effect, and electric double layer (EDL) electrokinetic effect, the Ink@VF-based EEG can achieve a maximum open-circuit voltage (Voc) of 0.65 V and an optimal power density of 43.72 mW/m² with 1 mol/L NaCl solution. It can also be integrated in series to develop a self-powered bracelet. Simultaneously, the evaporation rate and solar energy conversion efficiency of the Ink@VF-based SSG can reach 1.32 kg/m²/h and 84.9% under 1 sun irradiation, respectively. Through utilizing the evaporation-condensation mechanism, it can achieve freshwater generation at a rate of 1.49 kg/m²/h and metal ion removal in excess of 99.9%. This study provides a low-cost and efficient solution to the energy crisis and freshwater shortage in resource-poor remote areas by utilizing inexhaustible natural resources.