Hydrolyzed Hydrated Titanium Oxide on Laser-Induced Graphene as CDI Electrodes for U(VI) Adsorption

Abstract

Recently, laser-induced graphene (LIG), which has been successfully applied in CDI technology (directly without a complex preparation process), has gained considerable attention. However, the raw LIG electrode with a limited number of active sites exhibits low adsorption efficiency. Therefore, the search for a suitable and effective method to modify LIG to improve its electroadsorption performance is significant. Herein, a very simple titration hydrolysis method is adopted to modify LIG, resulting in a layer of hydrated titanium oxide (HTO) being synthesized on the surface of LIG. The LIG/HTO composites possess a good adsorption property since covering the surface of LIG with a layer of HTO can greatly improve the adsorption capacity of LIG. Moreover, with the addition of HTO, not only the proton transfer ability of LIG has been enhanced but also considerable specific capacitance has been enlarged. As a result, LIG/ HTO composite as CDI electrode displays a maximum theoretical adsorption capacity of 1780.89 mg/g at 1.2 V, and the capacitance of LIG/HTO composite material is 4.74 times higher than LIG. During the electroadsorption process, Ti 4+ is reduced to Ti 3+ under external voltage, and O 2 − is produced through oxidation. Meanwhile, part of the U (VI) is hydrolyzed into UO 3 •2H 2 O under the action of −OH, and some combine with O 2 − to produce UO 4 •4H 2 O.

Electrochemical Techniques for Uranium Extraction from Water

“…Laser-induced graphene (LIG), prepared via CO2-laser conversion of polyimide, or graphene prepared via the hydrothermal reduction of graphene oxide can generate porous graphene electrodes in situ [37,52,53]. Cao et al prepared LIG/Co4S3 electrodes that achieved an adsorption capacity as high as 2702.79 mg/g [37].…”