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[Display omitted] • Lanthanum hydroxide was firmly loaded on N -doped C layer modified ACF without binder. • LNA exhibited stable P electrosorption behavior after 5 adsorption–desorption cycles. • The Langmuir maximum electrosorption capacity of P on LNA was 70.656 mg/g. • Co-existing anions improved P removal in the order of Cl->NO 3 –>SO 4 2-> HCO 3 –>CO 3 2– • N -doped C layer promoted P electrosorption by affecting electronic structure of La. Binder-free La(OH) 3 supported activated carbon fiber (ACF) electrode with modification of N -doped C layer (named LNA) was developed for phosphate (P) electrosorption. The optimum electrosorption of P on LNA was achieved at pH = 4 and voltage = 4 V. The electrosorption capacity was 6.5 times that without voltage, and adsorption rate also increased by 9 times. The presence of 0.1 mol/L inorganic anions improved the electrosorption efficiency in the order of Cl->NO 3 –>SO 4 2->HCO 3 –>CO 3 2–. The regeneration study revealed that LNA still exhibited a high electrosorption capacity (29.91 mg/g) after 5 cycles. The mechanism of phosphate electrosorption of LNA was analyzed by kinetics, isotherms, FTIR and XPS, etc. The adsorption kinetics followed the pseudo-second-order model, and the adsorption equilibrium data were well described by the Langmuir isotherm. The Langmuir maximum electrosorption capacity of LNA was 70.66 mg/g. The electrosorption of phosphate was controlled by ion exchange, electrostatic attraction and the formation of surface complexes. N -doped C layer affected the local electronic structure of La and strengthened the interaction with lanthanum hydroxide, promoting the electrosorption of phosphate. The results demonstrated that LNA is a promising electrosorption material for efficient phosphate recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple and non-destructive three-electrode EIS method was established for ACF. • Equivalent circuits and one-dimensional EDLC electrodes were constructed. • Weaving patterns of ACF affect their electrochemical performance. • Volumetric adsorption capacity (VAC) and capacitance (VSC) are positively related. • Knitted ACFs show lower energy consumption than woven ACFs. Activated carbon fibres (ACFs) are successful electrode materials for capacitive deionization (CDI) owing to their excellent electrochemical properties and commercial availability, for example, with knitted or woven morphology patterns. However, the lack of a common and effective analytical framework to analyse the performance of ACFs is hindering further progress in the area. This study establishes an electrochemical impedance-based method to detect and investigate the electrochemical properties of ACF materials without destroying their original weaving patterns. Five commercial ACFs with two distinct patterns and similar specific surface areas were investigated. Data from electrochemical impedance spectroscopy (EIS) are compared to the desalination performance and energy consumption of the ACFs in a CDI cell. The weaving pattern played a role in the electrochemical properties and desalination performance. The volume-salt adsorption capacities in CDI were related to the volume-specific capacities in EIS, however, there was no significant difference between knitted and woven materials. Linked to EIS features, knitted ACFs consume less energy than woven ACFs for removing the same amount of NaCl from water. These results provide ACF researchers with a new, effective, and readily available approach for measuring the electrochemical performance of ACF materials via EIS. [ABSTRACT FROM AUTHOR]