Comparison of physicochemical, sorption and electrochemical properties of nitrogen-doped activated carbons obtained with the use of microwave and conventional heating

Abstract

A series of new nitrogen-doped activated carbons has been obtained via the reaction with urea and chemical activation of Polish brown coal. In order to obtain nitrogen groups bonded in different ways to the carbonaceous matrix, the modification with urea was performed at two different stages of processing, i.e. precursor or char. Additionally, the effects of conventional or microwave heating on the physicochemical parameters, sorption abilities as well as capacitance behaviour of the carbons prepared were tested. All the materials under investigation were characterized by elementary analysis, surface area measurements as well as estimation of the number of surface functional groups. The sorption properties of the materials were tested towards methylene blue at temperature of 25 °C. Moreover, symmetric supercapacitors containing organic electrolyte and prepared carbons were tested in Swagelok ® type cells by using CV, GCD and EIS methods. Depending on the variant of preparation, the final products were micro/mesoporous nitrogen-doped activated carbons of well-developed surface area ranging from 617 to 1117 m 2 /g, showing acidic or intermediate acid-base character of the surface and different contents of nitrogen functional groups varying from 1.0 to 5.6 wt%. The results obtained in this study showed that introduction of nitrogen and chemical activation of brown coal led to activated carbons with very good sorption capacity toward organic dyes as well as good electrochemical parameters. The specific capacitance was achieved up to 86 F/g for N-doped carbon obtained by microwave carbonization followed by chemical activation with potassium carbonate.

Adsorption of cationic dye on nanostructured biocarbons: kinetic and thermodynamic study

“…The content of H daf in samples RP, RPA, and RC lower than that in the precursor is a consequence of gasification of rich in hydrogen fragments of the precursor structure, and for biocarbon RP also gasification of the aromatic structures formed in the process of carbonization. A decrease in the content of nitrogen in the obtained adsorbents probably follows from a low resistance of nitrogen groups to carbon(IV) oxide in the activation with potassium carbonate (Kaźmierczak-Raźna et al 2019). As implied by the obtained data, the activation with potassium carbonate also contributes to removal of sulfur.…”

Chitin and chitin-cellulose composite hydrogels prepared by ionic liquid-based process as the novel electrolytes for electrochemical capacitors

“…The solubility of biopolymers in IL-based solvents is essential for opening up new prospects in the green fabrication processes of materials made of natural polymers. An increasing demand for eco-friendly components is noticeable almost in every aspect of modern life and energy storage technologies are no different [19][20][21][22][23][24]. An Electrochemical Double Layer Capacitor (EDLC), also known as a supercapacitor, is one of such electrochemical energy storage systems, which is a matter of interest in the investigation on new potential biopolymer applications [25][26][27][28].…”

Nitrogen-Doped Carbon Aerogels Derived from Starch Biomass with Improved Electrochemical Properties for Li-Ion Batteries

“…For this reason, the amount of nitrogen functional groups on the surface of unmodified carbons is generally low. Most of the methods for enriching carbon with nitrogen can be attributed to one of two main synthetic routes: thermal treatment of precursor or carbon compound in the presence of a nitriding agent as well as impregnation of the carbons with nitrogen-containing agent [ 32 , 34 , 35 , 36 , 37 , 38 ], or carbonization of plastics containing nitrogen in their structure [ 39 , 40 ]. Depending on the modification conditions and the applied methods, the type of nitriding agent, and the stage of the technological process of carbon production on which the modification was carried out, modified carbonaceous materials show various physical, chemical, electronic, and electrochemical properties.…”