Hydrogen-treated, sub-micrometer carbon beads for fast capacitive deionization with high performance stability. (June 2017)

• Record Type: Journal Article
• Authors: Krüner, Benjamin; Srimuk, Pattarachai; Fleischmann, Simon; Zeiger, Marco; Schreiber, Anna; Aslan, Mesut; Quade, Antje; Presser, Volker
• Is Part Of: Carbon. Volume 117(2017)
• Page Start: 46
• Page End: 54
• Publication Date: 2017-06
• Subjects: Capacitive deionization -- Porous carbon -- Activated carbon; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2017.02.054
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Novolac is a low-cost carbon precursor which can be used to derive nanoporous carbon beads in sub-micrometer size. In this study, we introduce this material as a novel electrode material for capacitive deionization (CDI) with high performance stability and superior desalination rate. The polymer beads were synthesized employing a self-emulsifying system in an autoclave, pyrolyzed under argon, and activated with CO2, yielding a specific surface area of 1905 m 2 g −1 with a high total pore volume of 1.26 cm 3 g −1 . After CO2 activation, the material shows a salt sorption capacity of ∼8 mg g −1, but the performance is highly influenced by functional groups, causing an inversion peak and fast performance decay. However, de-functionalization via hydrogen treatment is outlined as an effective strategy to improve the CDI performance. After hydrogen treatment of novolac-derived carbon beads, we obtained a salt sorption capacity of 11.5 mg g −1 with a charge efficiency of more than 80% and a performance stability of around 90% over more than 100 cycles. Particularly attractive for practical application is the very high average salt adsorption rate of 0.104 mg g −1 s −1, outperforming commercial activated carbons, which are commonly used for CDI, by at least a factor of two. Graphical abstract: