Graphene-synergized 2D covalent organic framework for adsorption: A mutual promotion strategy to achieve stabilization and functionalization simultaneously

Highlights: • An in-situ loading and mutual promotion strategy was proposed. • An oxime-modified graphene-synergized covalent organic framework was obtained. • The composite achieved the synergistic improvement of stability and functionality. • The composite possessed good adsorption performance for uranium and plutonium. - Abstract: Most of current absorbents are difficult to hold favorable stability and functionality simultaneously when used in condition of high acidity and strong radiation existing in nuclear industry. Herein, a new graphene-synergized 2D covalent organic framework (GS-COF) was obtained via an in-situ loading of a covalent organic framework (TDCOF) on graphene sheets based on a mutual promotion strategy proposed in this work. The corresponding oximation products, o-GS-COF, and also o-TDCOF as a reference object, were respectively prepared subsequently. The results of experiments confirmed that o-GS-COF possesses better acid and irradiation stability than that of o-TDCOF. Adsorption experiments showed that the adsorption capacity of o-GS-COF for uranium is 144.2 mg g⁻¹, higher than that of GO (92.5 mg g⁻¹) and o-TDCOF (105.0 mg g⁻¹), and the maximum adsorption capacity reaches 220.1 mg g⁻¹. In the multi-ions system, o-GS-COF also displayed good selective adsorption property for uranium with SF_U/M 35–100 for 5 coexisting divalent metal ions and 14–18 for 5 coexisting trivalent lanthanide ions. The proposed strategy successfully achieved the synergistic improvement of both stability and functionality for the desired adsorbing materials and is of considerable practical utility in the field of design and preparation of reliable high-performance absorbents.