A general approach to 3D porous CQDs/MxOy (M = Co, Ni) for remarkable performance hybrid supercapacitors

- 3D porous CQDs/MxOy (M = Co, Ni) nanostructures have been synthesized.
- CQDs could tune the morphology of products, and improve the performances.
- The CQDs/MxOy nanoarchitectures exhibited remarkable electrochemical performance.
- The composites displayed high specific capacity of 210.4 F g−1 with 74.8 W h kg−1.

To date, zero-dimensional carbon quantum dots (CQDs), as a new carbon nanomaterials, have attracted attention in the improvement of the electrical conductivity for electrode materials. However, few attempts have been made to the use of CQDs as the structure-directing agent for the assembly of functional micro/nanoelectrodes. Herein, we have developed a general, and simple strategy to fabricate 3D porous hierarchical carbon quantum dots (CQDs)/MxOy (M = Co, Ni) composite nanostructures from thermolysis of corresponding CQDs/M(OH)y, where CQDs play crucial role as a structure-directing agent in tuning the morphologies of the M(OH)y. With the merits of the large electroactive surface area, superior electronic conductivity of CQDs, and fruitful porous structure, the as-fabricated battery-type electrode materials present amazing supercapacitor performance. For example, the as-made porous hierarchical CQDs/Co3O4 nanoarchitectures exhibited remarkable electrochemical performance with 1603 F g−1 at 1 A g−1, excellent rate capacity of 70.6% from 1 to 100 A g−1, superior cycling ability (97.0% capacity remained after 2000 cycles). Furthermore, the CQDs/Co3O4//AC hybrid supercapacitor (HSC) exhibits a high specific capacity of 210.4 F g−1 with 74.8 W h kg−1. The present work can be enlarged for the design of other functional 3D hierarchical micro-nanostructures in the fields of energy storage, catalysis, and photo/electrocatalysis.

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