Efficient capacitive desalination over NCQDs decorated FeOOH composite

Abstract

Capacitive deionization (CDI) is emerging as a novel technology for seawater purification, with the electrode material playing a crucial role in desalination performance. In this study, we designed a nitrogen-doped carbon quantum dots decorated iron oxide hydroxide (NCQDs/FeOOH) composite by a facile hydrothermal strategy and investigated as the CDI cathode for desalination application. Microstructural analyses reveal that the composite features a relatively uniform nanoparticle-assembled network, hierarchical pore alignment, and abundant porosity. Electrochemical tests confirm its outstanding capacitance property and conductivity. In an initial NaCl aqueous solution of 2000 ​mg ​L⁻¹ ​at an applied potential of 1.4 ​V, the GAC_NaCl of NCQDs/FeOOH hybrid electrode reaches 56.52 ​mg ​g⁻¹, along with the remarkable cycling durability. Furthermore, CV (cyclic voltammetry) and ex situ XPS (X-ray photoelectron spectroscopy) characterizations indicate the predominantly pseudocapacitive desalination mechanism.