2021, Vol.31, No.4

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 4.82

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

Research on Graphene and its importance in the field of energy conversion and storage devices such as fuel cells, batteries, supercapacitors and solar cells has gained momentum recently. It is studied to be the most suitable electrode material for enhanced performance of supercapacitors in terms of charge–discharge cycles, specific capacitance, high power and energy densities and so on, specifically due to its high conductivity and large theoretical surface area. Unfortunately, it posits lot of challenges due to its irreversible stacking between the individual sheets resulting in the decrease in the Specific Surface Area (SSA) compared to the theoretically reported values. Numerous studies have been carried out to prevent this stacking in order to increase the surface area, thereby being a more suitable material for the manufacture of electrodes for supercapacitors as its capacitance greatly depends on the electrode material. To solve this problem, the conversion of two-dimensional graphene sheets to three-dimensional crumpled graphene structure has been verified to be the most effective approach. The study of crumpled graphene has been one of the recent trends in the field of energy storage applications in consumer electronics and hybrid vehicles as the process of crumpling can be controlled to suit the prospective device applications.

Carbon lives along with us in our daily life and has a vital role to play. It is present in the air and within all living organisms. Due to its handheld advantage in nano-properties that are utilized in many applications, carbon substrates came under limelight during the recent decades. Carbon substrates are most widely used in cancer detection, catalysis, bio-sensing, adsorption, drug delivery, carbon capture, hydrogen storage, and energy. Alongside, composite materials with carbon as an additive are also developing rapidly in applications like infrastructures, automobile, health care, consumer goods, etc. which became an integral chunk of our life. In this paper diferent types of carbon substrates and its applications, properties of the substrates were reviewed. The applications and methods of synthesis of carbon substrates are also dealt with a broad perspective.

The simultaneous use of KOH and nitrogen to manufacture carbon materials provides these materials with properties that the presence of only one of these additives would not give them, such as high porosity and reactivity. However, it is difcult to obtain nitrogen-doped carbon materials with both high porosity and high nitrogen content, as the KOH signifcantly reduces the nitrogen content. In this review the complex relationships between nitrogen content and nitrogen precursor amount, KOH amount and the activation temperature are discussed, with a focus on the diferent N-functional groups and the porosity of the fabricated carbons. Generally, increasing activation temperature and increasing KOH amount decrease the nitrogen content due to reactions with the N-containing substructures of carbon, resulting in the release of nitrogen as N2, HCN and other N gases. Increasing these parameters can also result in the reduction of pyridine-N while the amount of quaternary-N increases simultaneously. Besides this, an increase in the amount of nitrogen precursor leads to an increase in the porosity of N-doped materials. However, too high amounts of the nitrogen precursor generate an excess of nitrogen which blocks the pore system and consequently reduces the porosity of the doped carbons.