Effect of Pretreatment with Acids on the N-Functionalization of Carbon Nanofibers Using Melamine

Abstract

Nowadays, N-functionalized carbon nanomaterials attract a growing interest. The use of melamine as a functionalizing agent looks prospective from environmental and cost points of view. Moreover, the melamine molecule contains a high amount of nitrogen with an atomic ratio C/N of 1/2. In present work, the initial carbon nanofibers (CNFs) were synthesized via catalytic pyrolysis of ethylene over microdispersed Ni–Cu alloy. The CNF materials were pretreated with 12% hydrochloric acid or with a mixture of concentrated nitric and sulfuric acids, which allowed etching of the metals from the fibers and oxidizing of the fibers’ surface. Finally, the CNFs were N-functionalized via their impregnation with a melamine solution and thermolysis in an inert atmosphere. According to the microscopic data, the initial structure of the CNFs remained the same after the pretreatment and post-functionalization procedures. At the same time, the surface of the N-functionalized CNFs became more defective. The textural properties of the materials were also affected. In the case of the oxidative treatment with a mixture of acids, the highest content of the surface oxygen of 11.8% was registered by X-ray photoelectron spectroscopy. The amount of nitrogen introduced during the post-functionalization of CNFs with melamine increased from 1.4 to 4.3%. Along with this, the surface oxygen concentration diminished to 6.4%.

Editorial for Special Issue “Advanced Materials in Catalysis and Adsorption”

“…This Special Issue aims to cover the latest research on the design and development of advanced materials for adsorption and catalytic applications. The synthesis of various carbon nanomaterials (CNMs), including carbon nanofibers (CNFs), carbon nanotubes (CNTs), graphene-like materials, and carriers (Sibunit), is of particular interest [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The functionalization of CNMs with heteroatoms (i.e., nitrogen [ 1 , 6 , 7 , 8 ] and boron [ 3 ]) is an effective method for boosting the applicability of carbon nanomaterials as catalytic substrates.…”

“…The synthesis of various carbon nanomaterials (CNMs), including carbon nanofibers (CNFs), carbon nanotubes (CNTs), graphene-like materials, and carriers (Sibunit), is of particular interest [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The functionalization of CNMs with heteroatoms (i.e., nitrogen [ 1 , 6 , 7 , 8 ] and boron [ 3 ]) is an effective method for boosting the applicability of carbon nanomaterials as catalytic substrates. Another group of the designed materials belongs to the oxide-based supports, including zeolite catalysts [ 9 ], composite catalytic materials [ 5 , 10 , 11 , 12 ], mixed Mn-Zr-Ce-O oxides [ 13 ], and perovskite-like materials [ 14 ].…”

“…Advanced catalytic materials have been developed for diverse types of heterogeneous catalytic reactions, such as the hydrodechlorination of chloroaromatics [ 1 ]; the dehalogenation of halogenated hydrocarbons [ 2 ]; dechlorination via catalytic pyrolysis [ 1 , 2 , 4 ]; the catalytic coupling of CH 4 [ 14 ]; the catalytic processing of hydrocarbons and their mixtures into synthesis gas [ 10 , 11 ] or CNT and CNF materials [ 2 , 5 , 6 , 8 ]; the oxidation of carbon monoxide [ 13 ]; the hydrogenation of organic compounds [ 7 ]; and selective oxidation [ 9 ]. Such advanced materials can be also used for electrocatalytic applications involving the oxygen evolution reaction (OER) [ 12 ] and the electrocatalytic reduction of carbon dioxide (CO 2 RR) [ 15 ].…”

“…The produced B-doped graphene material (composed of three to eight monolayers) is characterized by a boron concentration of about 4 wt.% and a high specific surface area (SSA) of 800 m 2 /g. The post-functionalization of carbon nanofibers with nitrogen using melamine was described in [ 6 ]. Therein, the authors revealed that the preliminary acidic treatment of CNFs permits an increase in the amount of N-doping (from 1.4 to 4.3 wt.%), while preserving the structure and consistency of the initial carbon filaments.…”

“…The carbon erosion or metal dusting (MD) of bulk Ni-M and Co-M alloys can be used to produce carbon nanofibers and CNF-based composites [ 1 , 2 , 4 , 5 , 6 ]. The carbon erosion of nickel alloys during the catalytic pyrolysis of organic compounds with the formation of carbon nanofibers in a flow-through reactor and under reaction conditions in a close volume (Reactions under Autogenic Pressure at Elevated Temperature (RAPET)) has been extensively studied in [ 2 ].…”