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Various kinds of phenol-formaldehyde resins modified with urea have been firstly designed and synthesized; next, nitrogendoped carbon nanosheets with porous features are fabricated by a template-assisted carbonization method, using the resin as nitrogen and carbon sources, and commercial Mg(OH) 2 as template. Increasing the initial molar ratio of urea results in promoting porosity and N content. When a molar ratio of phenol and urea of 1 : 2 is employed, the resulting carbon nanosheets exhibit a large S BET (1503 m 2 g À 1 ), high pore volume (3.37 cm 3 g À 1 ) and high N doping (6.44 %). Moreover, the material delivers a remarkably improved capacitive performances with a high rate capability up to 81.27 % (pristine material: 27.31 %) and excellent cycling stability up to 119.1 % (pristine material: 88.5 %). Energy densities of up to 4.30 Wh kg À 1 (6.0 M KOH) and 10.42 Wh kg À 1 (1.0 M Na 2 SO 4 ) are found, which are almost 2.70 and 6.61 fold compared to that of the pristine one. The present resin-based synthesis strategy can be extended to other systems and opens up an avenue for producing N-doped carbon materials for supercapacitor applications.

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Herein, a strategy by balancing porosity and oxygen‐containing functionalities is successfully developed to efficiently modulate pore structures as well as relevant capacitive performance toward hierarchically porous carbon materials. It is revealed that the mass ratio of sodium citrate (producing porosity by a self‐template) and F‐127 (producing both porosity and pseudocapacitance) exerts a crucial role for achieving the aforementioned objective. In addition, when the mass ratio of sodium citrate to F‐127 reaches up to 1:1, the carbon sample delivers an excellent cycling stability of 98% within 10 000 cycles and the superior energy densities of 3.6 and 10.6 W h kg−1 when using 6 m KOH and 1 m Na2SO4 (voltage up to 1.8 V) as electrolytes, respectively, in a two‐electrode configuration. Thereby, by balancing the porosity (contribution to transport of electrolytes) and oxygen functionalities (contribution to additional pseudocapacitance), the present carbon materials enable integrated capacitive improvement for supercapacitors. The present scientific strategy of balancing porosity and heteroatom‐doping functionalities can be readily extended for producing other kinds of porous carbon materials especially used in the area of supercapacitors.