Dual‐Network Liquid Metal Hydrogel with Integrated Solar‐Driven Evaporation, Multi‐Sensory Applications, and Electricity Generation via Enhanced Light Absorption and Bénard–Marangoni Effect

Abstract

Solar‐driven evaporation is a promising strategy to relieve fresh water stress in the world. For an evaporator, it is necessary to be equiped with novel photothermal conversion materials and regulate heat energy loss in the solar‐driven generation process for evaporation efficiency. Herein, a novel eutectic gallium‐indium (EGaIn)/polyaniline (PANI) complex (EP) and cellulose nanocrystals (CNCs) are explored as the light absorber for broadband light absorbing and the dispersant for particles uniformity. Based on the Bénard–Marangoni effect, a dual‐network poly(vinyl alcohol)/poly(acrylamide) (PM) hydrogel as the evaporator and water/ethylene glycol as the solvent to regulate heat transfer. Specifically, with CNCs and EP incorporated, the hydrogel is endowed with excellent mechanical properties, photothermal conversion performance, and electrical characteristics. Surface temperature of the hydrogel can reach to ≈38.7 °C in water under 1 sun illumination for 1 h. Based on combination of broadband light absorption and the Bénard–Marangoni effect, its evaporation rate is higher than 1.50 kg m ^–2 h ^–1. The engineered synergy also gives the hydrogels with multiple sensory capabilities, skin‐like function, and power generation. This work demonstrates novel EGaIn‐based photothermal conversion particles and a new approach to regulate the heat transfer for highly solar‐driven evaporation, with a focus on the integration of multifunctional solar evaporation systems.