Tuning interlayer spacing and structural disorder in graphene nanosheets via organic amine-functionalization to construct hierarchical porous carbons for boosting capacitive deionization

Yang Fan ^a,1, Jian Yu ^a,1, Junjie Chen ^a, Junsong Zhang ^a, Ying Liang ^c, Haiou Song ^b,*, Shupeng Zhang ^{a, *}

Abstract

Capacitive deionization (CDI) is an emerging desalination technology which has received widespread attention because of its excellent cost-effective and environmental-friendly features. Graphene oxide (GO) is a prominent electrode material due to its excellent physicochemical characteristics, but it often suffers from aggregation which limits its applications in adsorption. To overcome this obstacle and further improve the electrosorption capacitance, herein for the first time we utilized a simple "one-pot" method for GO surface modification via amination with a double-alkoxyl-groups-containing small molecule- aminoacetaldehyde diethyl acetal (ADEA-GO). Then, porous carbons derived from a series of MOF material after high-temperature carbonization (MOFPN) were composited with ADEA-GO through ultrasonic treatment to afford ADEA-GO/MOFPN composites. Electrochemical performance showed that all newly developed ADEA-GO/MOFPN electrode materials exhibit an increment of specific capacitance compared to corresponding pristine MOF carbons. Among them, ADEA-GO compositing with the Zn, Co-bimetal ZIF derived porous carbon (ADEA-GO/BMZIFPN) has the highest specific capacitance characteristics (129.5 F g^-1). Moreover, CDI tests exhibit an excellent salt adsorption capacity of 17.18 mg g^-1 in a 250 mg L^-1 NaCl solution at 1.4 V with good reproducibility. Textural characterization and mechanistic study confirmed that the enhancement in electrosorption performance was attributed to the synergistic effect of the extension of porosity and structural disorder. This phenomenon originates from enlargement of graphene interlayer spacing and formation of a novel three-dimensional hierarchical porous network assisted by ultrasonic self-assembly as analyzed from a microscopic structural perspective. This article provides a new strategy to effectively functionalize graphene materials and improve the electrosorption performance of carbon-based electrode.

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https://www.sciencedirect.com/science/article/pii/S0011916424011809