Defect-rich N-doped porous carbon derived from alginate by HNO3 etching combined with a hard template method for high-performance supercapacitors

N-doped porous carbons have recently drawn increasing attention for energy storage devices due to large surface area, various N configurations, and environment friendliness. In this work, we have reported a defect-rich N-doped porous carbon (DNPC) derived from alginate via the combined processes of crosslinking sodium alginate (SA) by CaCO 3 hard template, a high-temperature carbonization , as well as HNO 3 etching for high-performance supercapacitors (SCs). The specific surface area and pore volume of the optimized DNPC sample are 1117 m 2  g −1 and 1.01 cm 3  g −1 , respectively. The effects of preparation parameters on structural features and electrochemical properties , including the mass ratios of CaCO 3 to SA, heating temperatures, and dosages of HNO 3 , are extensively investigated. Thanks to the advantages of developed porous structure, controllable N configurations, and large specific surface area, the DNPC1 sample displays superior specific capacitance (296 F g −1 ) and outstanding capacitance retention of 91% after 10000 cycles at 5 A g −1 . Additionally, a symmetrical SC with DNPC1 delivers energy densities of 12.9 and 18.9 W h kg −1 in KOH and Na 2 SO 4 electrolytes, respectively. This study presents a facile way to fabricate the N-doped porous carbons with controllable N configurations for energy storage devices.