Laser-induced 3D porous flower-like Fe2O3/reduced graphene oxide modified nickel foam electrode for enhanced capacitive deionization

Abstract

Capacitive deionization (CDI) is a desirable emerging technology for water treatment, however its performance is mainly limited by the properties of the electrode. In this study, we successfully prepared laser-induced 3D porous flower-like Fe2O3/reduced graphene oxide (rGO) modified nickel foam (NF) electrode (LIFG/NF). Consideration was given to the impacts of different laser etching power on the electrode performance. Results show that the flower-like Fe2O3 is well decorated on the surface of rGO, and the laser etching can form 3D porous structures on the electrode surface due to the photothermal effect and photochemical effect. The highest specific surface area (130.1 m2 g−1) and good wettability of the electrode (LIFG/NF-1.35) were obtained when the laser power was 1.35 W. With the introduction of pseudo-capacitance of Fe2O3 in the electrode, the electrochemical performance was improved. In CDI experiment, an excellent salt adsorption capacity (SAC, 95.07 mg/g) and average salt adsorption rate (ASAR, 1.36 mg/g/min) was obtained for the LIFG/NF-1.35 electrode with an applied voltage of 1.2 V when feed water was 250 mg/L of NaCl solution. In the recycle experiments for LIFG/NF-1.35 electrode, the SAC was 83.7 % of the initial electrode material after 15 cycles, revealing good deionization stability and reusability.