Preparation of Superhydrophobic PU@CuS via Electroless Plating and Its Application on Photothermal-Assisted Separation of High-Viscosity Crude Oil from Water

Crude oil spills pose serious challenges due to low fluidity and high viscosity. Researchers are exploring a range of sustainable cleanup solutions, such as using heating components to reduce oil viscosity. Herein, an electroless plating technique was adopted for depositing copper sulfide (CuS) on a polyurethane (PU) sponge by a coordination strategy. Subsequently, a layer of octadecyltrichlorosilane (OTS) was deposited to enhance the surface oil absorption ability. The PU@OTS-CuS sponge has demonstrated superhydrophobicity and remarkable oil absorption capability ranging from 11.5 to 47 g/g for oils with diverse viscosities. Moreover, it has sustained its 22.5 g/g oil absorption capacity for lubricant oils and separation efficiency of over 97% for the n-hexane and dichloromethane–water mixture even after undergoing 10 cycles. The surface temperature of the modified sponge was increased to 74 °C within 180 s under 1 sun irradiation and a sustained crude oil absorption capacity of 20 g/g even after 10 cycles. In continuous crude oil remediation, the modified sponge collected 3.257 g within 15 min at a rate of 0.542 g/min. Additionally, the modified sponge revealed superior stability against immersion in seawater and different pH solutions, exposure to UV light, sand abrasion, mechanical compression, and cyclic photothermal performance. This research presents a new strategy for depositing a photothermal component on sponge surfaces to improve crude oil cleanup.