Unique holey graphene/carbon dots frameworks by microwave-initiated chain reduction for high-performance compressible supercapacitors and reusable oil/water separation

Abstract

It is still a big challenge to integrate intrinsic modification and self-standing structure construction into graphene via a rapid and facile approach. Herein, we report a sampling and quick in situ chain reduction technology to prepare nitrogen-doped porous graphene frameworks. In this process, easily dispersible graphene serves as an effective receptor for microwave absorption and initiates the reduction of graphene oxide; the reduced part of GO becomes the microwave-absorbing receptor to cause a “chain reduction”, which allows the NPGFs to form in 3–5 s. The as-prepared graphene frameworks maintain the long-range layered structure of the precursor film, while the holey graphene sheets loaded with nanoparticles form a networked structure in the short range. Furthermore, the hierarchical framework with a high specific surface area shows interesting applications in supercapacitors and oil–water separation. The assembled compressible supercapacitor delivered a volumetric energy density of 12.3 mW h cm⁻³ at a power density of 0.42 W cm⁻³ and exhibits stable performance under compression. In addition, the graphene frameworks exhibited reusability with mechanical squeezing and extremely high volumetric absorption capacity of 100–243 g cm⁻³ for different oils and organic solvents, which is much higher than that in other reports (the performance index is ∼1 g cm⁻³). This study provides a new way to construct a multi-functional graphene self-standing structure, which presents potential application value in catalysis, energy storage, and environmental protection.