Composites containing resins and carbon nano-onions as efficient porous carbon materials for supercapacitors

Herein, we report the functionalization of carbon nano-onions (CNOs) with the hydroxyaryl group and subsequent modifications with resins: resorcinol-formaldehyde using porogenic Pluronic F-127, resorcinol-formaldehyde-melamine, benzoxazine made of bisphenol A and triethylenetetramine, and calix[4]resorcinarene-derived using F-127. Following the direct carbonization, extensive physicochemical analysis was carried out, including Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, and adsorption-desorption of N-2. The addition of CNO to the materials significantly increases the total pore volume (up to 0.932 cm(3) g(-1) for carbonized resorcinol-formaldehyde resin and CNO (RF-CNO-C) and 1.242 cm(3) g(-1) for carbonized resorcinol-formaldehyde-melamine resin and CNO (RFM-CNO-C)), with mesopores dominating. However, the synthesized materials have poorly ordered domains with some structural disturbance; the RFM-CNO-C composite shows a more ordered structure with amorphous and semi-crystalline regions. Subsequently, cyclic voltammetry and galvanostatic charge-discharge method studied the electrochemical properties of all materials. The influence of resins' compositions, CNO content, and amount of N atoms in carbonaceous skeleton on the electrochemical performance was studied. In all cases, adding CNO to the material improves its electrochemical properties. The carbon material derived from CNO, resorcinol and melamine (RFM-CNO-C) showed the highest specific capacitance of 160 F g(-1) at a current density of 2 A g(-1), which is stable after 3000 cycles. The RFM-CNO-C electrode retains approximately 97% of its initial capacitive efficiency. The electrochemical performance of the RFM-CNO-C electrode results from the hierarchical porosity's stability and the presence of nitrogen atoms in the skeleton. This material is an optimal solution for supercapacitor devices.

Automated summary

In this study, carbon nano-onions (CNOs) were functionalized with hydroxyaryl groups and then modified with different types of resins. The resulting materials were characterized using various techniques including spectroscopy and microscopy. The addition of CNO significantly increased the total pore volume of the materials, with mesopores dominating. The electrochemical properties of the materials were also studied, and it was found that adding CNO improved the performance. The carbon material derived from CNO, resorcinol, and melamine showed the highest specific capacitance and was considered an optimal solution for supercapacitor devices.