Constructing fluorine-free and photothermal MXene/candle soots-based superhydrophobic sponge for oil/water separation, crude oil recovery, and anti-icing

Offshore oil spills and the uncontrolled discharge of oily wastewaters have detrimental impacts on marine ecosystems and environments. In this study, a fluorine-free superhydrophobic melamine sponge (MS) with the photothermal property is achieved by introducing MXene and candle soots via the adhesion of PDMS. The engineered superhydrophobic sponge shows high chemical and thermal stabilities, and excellent mechanical durability. Its adsorption capacities vary from 48.0 to 100.4 g/g for diverse oils and organic solvents, showing a highest adsorption capacity of 100.4 g/g for ethylene glycol and a saturated adsorption capacity of 71.1 g/g for viscous crude oil. Due to the synergistic photothermal conversion between candle soots and MXene, superhydrophobic MS displays a maximum surface temperature of 75.6 ℃ under 1 sun irradiation, quickly adsorbs a droplet of crude oil (0.5 mL) within 26 s under 1 sun irradiation, and realizes ice-free property at −17.5 ℃ under solar irradiation (0.4 suns), respectively. This study provides a facile and low-cost approach to utilize wastes (candle soots) in a high-value added way, which extends the applications of superhydrophobic MS with multifunctionality in the fields of oil/water separation, crude oil recovery, and active de-icing.