Construction and Properties of Wood-Based Tannin–Iron-Complexed Photothermal Material Populus tomentosa Carr.@Fe-GA for Solar Seawater Desalination System

Desalinating seawater is a crucial method for addressing the shortage of freshwater resources. High-efficiency, low-cost, and environmentally friendly desalination technologies are key issues that urgently need to be addressed. This work used <i>Populus tomentosa Carr.</i> as a matrix material and prepared <i>Populus tomentosa Carr.</i>@Fe-GA through a complexation reaction to enhance the water evaporation rate and photothermal conversion efficiency of seawater desalination. The concentration of the impregnation solution was further refined, and the bonding mechanism along with the thermal stability of the composite photothermal material was investigated, including an assessment of their photothermal conversion efficiency. The research results indicate that the evaporation rate of water in a 3.5% NaCl solution for <i>Populus tomentosa Carr.</i>@Fe-GA under light intensity conditions of one sun reached 1.72 kg·m^-2·h^-1, which was an increase of 44.5% compared to untreated <i>Populus tomentosa Carr.</i> It achieved a photothermal conversion efficiency of 95.1%, an improvement of 53.6% over untreated <i>Populus tomentosa Carr.</i>, and maintained stability and high evaporation performance (95.4%) even after prolonged rinsing. This work realizes the functional utilization of seawater desalination with <i>Populus tomentosa Carr.</i> and offers a novel approach for the development and use of wood-derived photothermal material.