Lightweight graphene oxide-based sponges with high compressibility and durability for dye adsorption

Development of lightweight porous structure with high compressibility and mechanical durability is in great demand to promote graphene-based materials from fundamental research to engineering applications. In this study, graphene oxide (GO)-based sponges with hierarchical porous structures were synthesized by a simple freeze-drying method. By controlling and optimizing their structures, the lightweight GO-based sponges can offer excellent structural integrity even after being compressed at 95% strain, indicating the extremely high compressibility. The outstanding mechanical durability were also demonstrated by cyclic compression testing at 50% strain for 10,000 cycles. Considering the severe dye pollution problem, the sponges were investigated for methylene blue adsorption. It was found that the sponges with high selectivity during adsorption can have the maximum adsorption capacity up to 476 mg g(-1). More importantly, the sponges were demonstrated with extraordinary recyclability along with a very simple recycling process and also high recycling efficiency (above 86% after the 10th cycle). It was experimentally demonstrated that if their morphological structures are carefully designed and optimized, the GO-based porous structures can exhibit the ensemble of outstanding compressibility and durability, and equally importantly the excellent adsorption performance. Therefore, it could show great promise of such nanomaterial-based sponges as excellent adsorbents for wastewater purification. (C) 2020 Elsevier Ltd. All rights reserved.