A three-dimensional polyoxometalate/graphene aerogel as a highly efficient and recyclable absorbent for oil/water separation

Three-dimensional (3D) graphene aerogels (GAs) with a tunable pore structure, a highly accessible surface area, and exceptional compressibility, elasticity and wettability have been explored as promising absorbents for efficient oil/water separation. However, the strategies for assembling 3D GAs usually involve a high-temperature process, resulting in high cost. We report the synthesis of a 3D porous polyoxometalate (POM)-hybridized GA (POM-GA) as a highly efficient and recyclable absorbent for oil/water separation. The material was fabricated at room temperature by the self-assembly and reduction of graphene oxide using POM as a functional cross-linker and hydrazine hydrate as a reductant. It had a 3D interconnected macroporous structure, a large specific surface area, and exceptional compressibility, elasticity and wettability, and had excellent absorption capacities of 100－210 g g⁻¹ for the rapid removal of various organic pollutants from water, outperforming most of the previously reported graphene-based macro-assemblies synthesized at high temperatures. Moreover, the absorbed oils can be readily removed by squeezing or first squeezing and then burning the remaining organic from the 3D POM-GA. The oil-absorption capacity retention rates of the 3D POM-GA are 96 and 90% after 10 absorbing-squeezing and absorbing-squeezing-burning cycles, respectively. The material therefore has great potential for efficient oil/water separation with wide applicability and excellent durability.