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Ni ink-catalyzed conversion of a waste polystyrene−sugar composite to graphitic carbon for electric double-layer supercapacitors
Date Issued
2020-10-27
Author(s)
Gupta, Ritu
Urgunde, Ajay B.
Bahuguna, Gaurav
Dhamija, Anandita
Das, Parijat P.
DOI
10.1021/acsaelm.0c00542
Abstract
The disposal of organic waste materials such as polymers is a serious problem to natural ecosystems as some of them can be non-biodegradable and potentially toxic. Thus, there is immense interest in developing processes that convert waste polystyrene into useable carbon. In this work, we developed a unique approach for obtaining graphitic carbon from waste polystyrene as a raw carbon source. The conversion process is catalyzed using the Ni-butanethiolate ink in ultralow quantities under an optimized temperature (800 °C) in the presence of 5% hydrogen in nitrogen. Interestingly, macroporous sugar cubes are used as a soft template to hold polystyrene and the catalyst together during decomposition, eliminating the need for a high-pressure source for retaining carbon for graphitization at high temperatures. An additional step of hydrogen annealing for pyrolyzed carbon nullifies the surface effects and improves the graphitization, reduces the point defects, and enhances the crystallinity of carbon and electrical conductivity specifically required for an electric double-layer capacitor (EDLC). The SPC8H-based graphitic carbon electrode exhibits perfect rectangular cyclic voltammetry characteristics with a symmetric triangular charge−discharge curve and a specific capacitance of ∼158 F/g at 1 A/g. The two-electrode EDLC device demonstrated excellent cyclic stability with a capacitance retention of ∼90% even after 10,000 cycles. This study reveals that the trashed polystyrene waste could be transformed into highly crystalline, graphitic carbon electrodes for energy storage devices. This indeed offers an alternative and sustainable approach with a low price to high-performance ratio that can probably manage the issue of white pollution at a commercial scale.