A Polyoxometalate‐Based Binder‐Free Capacitive Deionization Electrode for Highly Efficient Sea Water Desalination

Abstract

Capacitive deionization is a promising technique in sea water desalination. Compared with common electrodes, mixed capacitive‐deionization electrodes exhibit better performance in sea water desalination because they integrate pseudocapacitance and electric double‐layer capacitance in one system. Herein, a 3D binder‐free mixed capacitive‐deionization electrode was fabricated by direct electrodeposition of SiW12O404− and polyaniline on a 3D exfoliated graphite carrier. In this electrode, SiW12O404−/polyaniline composite particles with a size of about 100–120 nm are dispersed homogenously on the 3D exfoliated graphite carrier. Its specific capacitance reaches 352 F g−1 at 1 A g−1. With increasing current from 1 to 20 A g−1, the specific capacitance only decays by 32 %. When employed in sea water desalination, the performance of this mixed capacitive‐deionization electrode is also excellent. At 1.2 V, the salt adsorption capacity of this mixed electrode reaches 23.1 mg g−1 with a salt adsorption rate of 1.38 mg g−1 min−1 in 500 mg L−1 NaCl. The performance of this electrode is well retained after 30 cycles. The excellent sea water desalination performance originates from the synergistic effect between SiW12O404− and polyaniline. This work has developed polyoxometalate as a new material for capacitive‐deionization electrodes.

Dimensional optimization enables high-performance capacitive deionization

“…4À /polyaniline (particles) on the 3D ake graphite carrier, which was used as one of the CDI electrode materials. 288 The composite electrode benets from the interaction of the 3D structure and composite nanoparticles (particle size: 100-120 nm), showing excellent desalination performance. 288 At 1.2 V, the capacity of the adsorbing salt of the hybrid CDI electrode reached 23.1 mg g À1 , and the salt adsorption rate in 500 mg L À1 NaCl was 1.38 mg g À1 min À1 .…”

“…288 The composite electrode benets from the interaction of the 3D structure and composite nanoparticles (particle size: 100-120 nm), showing excellent desalination performance. 288 At 1.2 V, the capacity of the adsorbing salt of the hybrid CDI electrode reached 23.1 mg g À1 , and the salt adsorption rate in 500 mg L À1 NaCl was 1.38 mg g À1 min À1 . Different from other electrode materials, redox-active polymer electrode materials provide another effective way for the application of CDI seawater desalination.…”

Recent progress in materials and architectures for capacitive deionization: A comprehensive review

“…Liu, Zhang, Xu, and Wang (2020) used polyoxometalate based binder free electrode with specific capacitance 352 F/g and SAC 23.1 mg/g. Tu et al (2019) and Nie et al (2020) synthesized polyaniline doped activated carbon as one of the electrodes in HCDI showing SAC of 27.6 mg/g for former and 30.5 mg/g for latter.…”

Construction of Novel Biomass‐Based Solar Evaporator with Asymmetric Dual‐Layer Structure for Water Desalination

“…the destruction and pollution of water resources caused by industrial development has caused the world to face serious water shortages in recent years. [6,7] Although traditional seawater desalination technology can effectively and quickly treat seawater, it consumes a lot of fossil energy and produces a lot of pollutants, which will cause incalculable harm to the local ecological environment. [8][9][10] Therefore, the development of novel, high-efficient, and pollution-free seawater desalination technology is much needed.…”