Nitrogen-doped porous carbons with ultrahigh specific surface area as bifunctional materials for dye removal of wastewater and supercapacitors

Abstract

In this work, the nitrogen-doped porous carbon (PCM-K) with ultrahigh specific surface areas has been prepared successfully by using biomass pine nut shell as a precursor. The as-synthesized PCM-K exhibits an ultrahigh specific surface area of 3376.1 m2·g−1, a large pore volume of 1.655 cm3·g−1 and a high nitrogen content of 6.25%. By exploring the removal ability of PCM-K for cationic dye methylene blue (MB) in wastewater, and examining the effects of various experimental factors, such as contact time, initial dye concentration, adsorbent dosage and temperature on the MB removal from wastewater, it is found that the PCM-K not only exhibits excellent MB adsorption capacity of 766.9 mg·g−1, which is higher than 704.3 mg·g−1 of rhodamine B and 408.7 mg·g−1 of methyl orange, but also shows almost 100% removal efficiency of MB from wastewater. Owing to the high nitrogen content, the PCM-K also exhibits excellent electrochemical performance as supercapacitors. Galvanostatic charging–discharging measurements showed that the specific capacitance of PCM-K in a three-electrode system reaches 376.4 F·g−1 in 6 M KOH and at a current density of 0.1 A·g−1. The excellent dye removal and electrochemical performances suggest that the biomass-derived nitrogen-doped porous carbons is a promising candidate for wastewater treatment and energy storage.