Designed fabrication of hierarchical porous carbon nanotubes/graphene/carbon nanofibers composites with enhanced capacitive desalination properties
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Carbonaceous materials, one of the most important electrode materials for sea water desalination, have attracted tremendous attention. Herein, we develop a facile and effective two-step strategy to fabricate hierarchical porous carbon nanotubes/graphene/carbon nanofibers (CNTs/G/CNFs) composites for capacitive desalination application. Graphite oxide (GO), Ni2+, and Co2+ are introduced into polyacrylonitrile (PAN) nanofibers by electrospinning method. During the annealing process, the PAN nanofibers are carbonized into CNFs felt, while the CNTs grow in situ on the surface of CNFs and graphite oxide are reduced into graphene simultaneously. Benefiting from the unique hierarchical porous structure, the as-prepared CNTs/G/CNFs composites have a large specific surface area of 223.9 m2 g−1 and excellent electrical conductivity. The maximum salt capacity of the composites can reach to 36.0 mg g−1, and the adsorbing capability maintains a large retention of 96.9% after five cycles. Moreover, the effective deionization time of the CNTs/G/CNFs composites lasts more than 30 min, much better than the commercial carbon fibers (C-CFs) and graphene/carbon nanofibers (G/CNFs) composites. Results suggest that the designed hierarchical porous CNTs/G/CNFs architecture could enhance the capacitive desalination properties of electrode materials. And the possible adsorption mechanism of the novel electrode materials is proposed as well.
We gratefully acknowledge the financial support from the Taishan Scholar Project (No. ts201511080) and the National Natural Science Foundation of China (NSFC) (51302049, 51372052 and 51672059). Project of Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (HIT.NSRIF.2015106, HIT. NSRIF. 2014129) and Technology Development Program at Weihai (2013DXGJ12) are also acknowledged.
The manuscript was written through contributions of all authors. C.Z., Y.H. and G.W. conceived and designed the experiments; C.Z. and Y.H. performed the experiments; Y.H. and T.Z. analyzed the data; H.W. contributed analysis tools and relevant analysis.
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Conflict of interest
The authors declare that they have no conflict of interests.