Preparation\nof Dual-Doped N/P Two-Dimensional Porous\nCarbon Nanosheets for High-Performance Alkaline Supercapacitors

Abstract

Combining\nmultiple heteroatom codoping with unique 2D carbon nanoarchitecture\nis an appealing strategy for enhancing the electrochemical performance\nof carbon electrodes. In this work, we offer a two-step avenue to\nmanufacture N/P codoped 2D porous carbon nanosheets (NP-PCNs) for\nsupercapacitor electrodes. The 2D PCNs are first obtained via the\nexplosion-assisted technique along with carbonization and acid washing\nusing zinc nitrate and lactose as raw materials. Then, the PCNs are\ncoated by poly­(cyclotriphosphazene-<i>co</i>-polyethyleneimine)\nas carbon, phosphorus, and nitrogen sources, followed by direct carbonization\nto produce NP-PCNs. The resultant optimized sample NP-PCNs-100 integrates\nthe architectural features of rich heteroatom codoping amount (3.47\nat. % for N and 2.64 at. % for P), moderate specific surface area\n(239 m² g^–1), and hierarchical porosity\n(micro-, meso-, and macropores). Electrochemical tests display that\nthe NP-PCNs-100 presents a high specific capacitance of 322.9 F g^–1 at 1 A g^–1 and maintains its specific\ncapacitance of as high as 64.4% (207.9 F g^–1) at\n20 A g^–1, manifesting an attractive rate performance.\nMoreover, the assembled symmetrical supercapacitor device using the\ntypical sample NP-PCNs-100 can achieve a high energy density of 17.04\nW h kg^–1 at a power density of 400 W kg^–1 and deliver a superb cycling stability (capacitance retention of\n90% after 10,000 cycles).