Novel mesoporous Co(3)O(4)–Sb(2)O(3)–SnO(2) active material in high-performance capacitive deionization

Capacitive deionization (CDI), as an emerging eco-friendly electrochemical brackish water deionization technology, has widely benefited from carbon/metal oxide composite electrodes. However, this technique still requires further development of the electrode materials to tackle the ion removal capacity/rate issues. In the present work, we introduce a novel active carbon (AC)/Co(3)O(4)–Sb(2)O(3)–SnO(2) active material for hybrid electrode capacitive deionization (HECDI) systems. The structure and morphology of the developed electrodes were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer–Emmett–Teller (BET)/Barrett–Joyner–Halenda (BJH) techniques, as well as Fourier-transform infrared (FT-IR) spectroscopy. The electrochemical properties were also investigated by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The CDI active materials AC/Co(3)O(4) and AC/Co(3)O(4)–Sb(2)O(3)–SnO(2) showed a high specific capacity of 96 and 124 F g(−1) at the scan rate of 10 mV s(−1), respectively. In addition, the newly-developed electrode AC/Co(3)O(4)–Sb(2)O(3)–SnO(2) showed high capacity retention of 97.2% after 2000 cycles at 100 mV s(−1). Moreover, the electrode displayed excellent CDI performance with an ion removal capacity of 52 mg g(−1) at the applied voltage of 1.6 V and in a solution of potable water with initial electrical conductivity of 950 μs cm(−1). The electrode displayed a high ion removal rate of 7.1 mg g(−1) min(−1) with an excellent desalination–regeneration capability while retaining about 99.5% of its ion removal capacity even after 100 CDI cycles.