Although g‐C3N4 possesses many features such as a graphene‐like 2D π‐conjugated planar layered structure, high nitrogen content, excellent mechanical strength and flexibility, as well as high thermal and chemical stability, there are only a few studies on the exploration of g‐C3N4 as active materials for supercapacitors. This could be largely attributed to the fact that the above advantages of g‐C3N4 to hybrid with other materials are still not fully established. Herein, we successfully develop a facile low‐temperature CVD method to grow g‐C3N4 ultrathin films with several nanometers thickness on the surface of NiCo2O4 nanoneedles. Subsequently, a NiCo2O4 nanoneedles@g‐C3N4 ultrathin film core‐shell nanostructures/carbon cloth (NiCo2O4 NNs@g‐C3N4/CC) integrated electrode was obtained. Thanks to the ultrathin film, a core‐shell nanostructure, as well as intrinsic features of g‐C3N4, the as‐obtained integrated electrode displays excellent electrochemical performance, exhibiting an areal capacitance of 2.83 F cm−2 as well as high cycling stability (5.88 % loss after 10 000 cycles). Our results clearly demonstrate that the g‐C3N4 ultrathin film obtained through this facile CVD method developed has potential in hybridizing with other transition metal oxides as electrode materials for supercapacitors and, more importantly, this convenient synthesis method may also be widely used for other applications such as designing new heterojunction photocatalysts.
Non‐graphitic nitrogen plays a significant role in determining the electrochemical performance of carbon materials in the field of energy storage. However, the synthesis of carbon materials with a high level of non‐graphitic nitrogen doping is still a great challenge. In this paper, a facile one‐step pyrolysis approach was developed to synthesize 2D carbon nanosheets with a ultrahigh non‐graphitic nitrogen content. Through an ingenious design, g‐C3N4 and NH3, both generated during the pyrolysis process, play major roles in the generation of the non‐graphitic nitrogen‐doped carbon nanosheets. The intermediate g‐C3N4 acts as both a self‐sacrificial template and a nitrogen source, whereas NH3 offers a nitrogen‐enriched chemical atmosphere. Benefiting from the high pyridinic‐nitrogen content of the maternal g‐C3N4 and the reductive atmosphere of NH3, the as‐prepared carbon nanosheets exhibit a strikingly high non‐graphitic nitrogen content (up to 17.36 wt.%); also, thanks to the g‐C3N4 self‐sacrificial template, the as‐synthesized carbon nanosheets are 2D with an ultrathin thickness (3–4 nm) and a porous structure. These novel features make the as‐prepared carbon nanosheets an excellent supercapacitor electrode material in terms of superior specific capacitance (316.8 F g−1 at 1 A g−1), excellent cycling stability (without obvious capacitance loss after 10 000 cycles at 10 A g−1) and high energy density (up to 10.56 Wh kg−1 at a power density of 500 W kg−1). This work provides a new idea to prepare non‐graphitic nitrogen enriched carbon materials.
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