Biorenewable Polymer-Based Light-Absorbing Porous Hydrogel for Efficient Solar Steam Desalination

Abstract

An efficient interfacial heating system composed of alight-absorbingmaterial and a hydrophilic porous support is developed through eco-friendlyand energy-effective fabrication processes. Lignin nanoparticles (NPs)and cellulose nanofibers (CNFs) are harnessed as biorenewable lightabsorbers and hydrophilic supports, respectively. Lignin NPs are preparedusing a solvent exchange process of the fractionated lignin with organicsolvents to improve its pi-pi stacking and light-absorbingproperty for efficient photothermal conversion. Then, the lignin NPsare mixed with CNFs and lyophilized to obtain a light-absorbing poroushydrogel (LAPH), and the resulting LAPHs are covalently cross-linkedand hybridized with Au NPs through a seed-mediated growth to furtherenhance their mechanical stability, hydrophilicity, and photothermalconversion properties. The resulting LAPHs exhibit an outstandingand prolonged performance as a solar steam generator such as highsalt and pH tolerance, evaporation rate (3.17 kg m(-2) h(-1)), and solar steam generation efficiency (83.4%)under 1 sun irradiation.