Boosting solar steam generation by photothermal enhanced polydopamine/wood composites

Solar steam generation is an emerging strategy for water desalination using renewable solar energy and seawater resources. In order to convert solar energy into heat for seawater evaporation, we developed a bi-layered structure composite for high-efficient solar evaporation based on photothermal-enhanced arginine-doped polydopamine (APDA) and raw wood, which are biodegradable and sustainable. Note that the APDA coating layer exhibited improved optical absorption and photothermal conversion ability compared with conventional polydopamine (PDA) coating on account of the construction of donor-acceptor pairs within the APDA microstructure system. Density functional theory (DTF) calculation further confirmed that the energy bandgap of APDA could be narrowed though donor-acceptor microstructures and then enhanced the absorption spectrum. The resulting APDA-wood composite performed a solar vapor generation efficiency of ~77% on the condition of 1 sun illumination. The water evaporation process was quite stable over 100 cycles and the metal ions in seawater were almost eliminated after desalination. This amino acid-initiated cost-effective and facile coating method provided new opportunities to fabricate photothermal-enhanced coating materials for solar evaporation applications.