Multifunctional oligomer sponge for efficient solar water purification and oil cleanup

Conjugated small molecules have been extensively applied in the biomedical field owing to their tunable light-harvesting capability. However, their narrow absorption spectra limit their applications in solar water evaporation. Herein, a stable conjugated molecule DPP-2T with strong intermolecular interaction is shown to exhibit a wide optical absorption range over 250 to 1000 nm. By incorporating DPP-2T into a 3-dimensional porous polymer network, a highly elastic composite sponge with high solar–thermal conversion efficiency is obtained. The composite sponge shows a high and stable solar water evaporation rate of 2.60 kg m−2 h−1 with a solar water evaporation efficiency of 89% under 1 sun illumination. An efficient metal-removal efficiency of over 99% is achieved for purifying contaminated water by solar evaporation. On the other hand, it was also found to have good oil absorption capacity and can absorb silicon oil of 4 times its mass. Owing to the good elasticity of the composite sponge, the absorbed oil can be easily squeezed out and the foam can be reused for ten cycles with only a mild capacity decrease.