Molecular scissoring strategy to modify band gap and molecular motion for high-performance solar desalination and water purification

Abstract

Organic photothermal materials show great potential in solar-driven interfacial water evaporation due to their tunable optical and electronic properties. Rational molecular structural engineering in the energy band and absorption spectrum aspects to enhance their intrinsic photothermal properties is a key technology. In this work, a “scissoring” strategy was applied to modify the molecular structure of ITIC-4F, yielding IEIC-4F, which exhibits an improved photothermal conversion efficiency of up to 55.5% due to a narrowed bandgap and broadened near-infrared absorption. When loaded onto a wood sponge with hierarchical pores, which strengthened light-capture and heat-insulation abilities, the material system demonstrated excellent solar evaporation performance, achieving a rate of 1.76 kg m⁻² h⁻¹ and an efficiency of 91.8% in desalination. Moreover, IEIC-4F demonstrates significant intrinsic photocatalytic capacity to generate reactive oxygen species (ROS), resulting in a 99.9% antibacterial rate. By constructing a heterojunction with PM6, further enhancement in ROS generation was achieved leading to improved algal inhibition performance. Hence, we have established a synergistic material design strategy spanning from the molecular to the micro-nano scale and constructed a multifunctional solar-driven system that simultaneously enables efficient seawater desalination and water management.