In situ construction of metal-organic frameworks on chitosan-derived nitrogen self-doped porous carbon for high-performance supercapacitors.

The intelligent use of regenerable and degradable biomass materials to substitute the synthetic materials can bring huge economic benefits and environmental improvements. In addition, metal-organic framework (MOF) based cathode materials are becoming a research hotspot for supercapacitors. Here, Co nanoparticle-modified nitrogen self-doped porous carbonized chitosan aerogel (CCA-Co) precursors were prepared by sol-gel, freeze-drying technique and carbonization process using biomass chitosan particles and cobalt compounds as raw materials. Then the layered composite (CCA-Co@MOF) was obtained by growing Co-doped Ni MOF (Co-Ni MOF) with CCA-Co precursor as the carrier. Notably, the presence of Co nanoparticles in carbonized chitosan aerogel (CCA) not only promotes the self-assembly of CCA and MOF, but also etched Co ions can participate in the growth of MOF, resulting in excellent electrochemical performance. Specifically, the specific capacitance of CCA-Co@MOF reaches 1877.2 F g-1, which is much superior to CCA-M@MOFs (M = Ni, Zn and Cu) and other contrast materials. Furthermore, the asymmetric supercapacitor (CCA-Co@MOF//AC ASC) assembled using CCA-Co@MOF and activated carbon (AC) electrodes, exhibits a high energy density (45.9 Wh kg-1 at 431.7 W kg-1). This work highlights the advantages of metal nanoparticle-modified and carbonized chitosan aerogels for MOF growth, demonstrating its great value in the field of electrochemical energy storage.