Biomass-derived porous carbon anode for high-performance capacitive deionization.

Abstract The carbon material derived from citrus peel was prepared via hydrothermal synthesis method with low amount of ZnCl 2. The morphology and surface structure of the synthesized carbons were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and N 2 adsorption/desorption isotherms measurements. The electrochemical and capacitive deionization performance of carbon materials were comparatively studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). Compared with the materials activated with KOH or H 3 PO 4 , ZnCl 2 -activated carbon showed the best electrochemical double-layer characteristics, with the specific capacity of 120 F g−1. When being applied as anode in the capacitive deionization (CDI) cell, the desalination amount of 16 mg g−1 and the average salt adsorption rate (ASAR) of 0.67 mg g−1 min−1 were achieved, which is much higher than those of KOH- and H 3 PO 4 -activated materials. The desalination amount retained 80% after 35 cycles. The possible mechanism is proposed in light of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis. This work provides a facile and environmentally friendly method for the preparation of a green and low cost biomass derived porous carbon material by fruit waste with a low amount (1% mass) of activation regents for high performance capacitive deionization. Graphical abstract Image 1 Highlights • The porous carbon derived from fruit waste was prepared via hydrothermal synthesis method. • The carbon activated with low amount (1% mass) of ZnCl 2 showed the best porous characteristics. • The ZnCl 2 -activated carbon exhibited the best electrochemical and desalination performance. • The +C-Zn||AC cell shows high desalination rate and excellent desalination and regeneration stability. [ABSTRACT FROM AUTHOR]