Eco-friendly and easy-to-prepare three-dimensional network constructed by tannic acid/polypyrrole/sodium alginate via triple action mechanism of Fe3+ for highly-efficient solar evaporation

Solar-driven interfacial evaporation (SIE) represents a promising desalination technology leveraging solar energy and seawater. Nevertheless, the majority of SIE systems face constraints such as high costs, intricate fabrication processes, and limited tolerance to salt. Therein, we designed and developed an eco-friendly, simple, and low-cost way to construct independent and elastic three-dimensional networks using tannic acid (TA), polypyrrole (PPy), and sodium alginate (SA) via the triple action mechanism of Fe 3+ for efficient water evaporation (TPS-x). When the mass ratios of PPy and TA are designed as 1:2, 1:1, 2:1, and 3:1, and crosslinked with sodium alginate and FeCl 3 , four composites (TPS-1, TPS-2, TPS-3, and TPS-4) are obtained, in which the light absorption and evaporation properties of TPS-3 are the optimal, with an evaporation rate up to 2.451 kg m −2  h −1 and a photothermal conversion efficiency up to 84.74 %. Additionally, the TPS-3 evaporator has excellent stability and salt tolerance, maintaining more than 95.5 % of its original evaporation rate after 20 days of cycling tests. Due to its exceptional photothermal evaporation performance, TPS-3 shows potential for practical commercial applications, particularly in the fields of wastewater treatment and desalination.