Plasma-assisted preparation of NiCoAl-layered double hydroxides with a large interlayer spacing on carbon cloth for electrochemical deionization
Capacitive deionization has been considered an emerging desalination technique in recent years,especially for its economic and energy-saving characteristics for brackish water.However,there are currently few studies on chloride ion removal electrodes,and the slow desalination kinetics limits their development.Ar-NiCoAl-layered double hydroxide(LDHs)@ACC materials with an increased interlayer spacing were prepared by the in-situ growth of NiCoAl-LDHs nanosheet arrays on acid-treated carbon cloth(ACC)and subsequent argon plasma treatment.The carbon cloth suppresses the agglomeration of the NiCoAl-LDHs nanosheets and improves the electrical conductivity,while the plasma treatment increases the interlayer spacing of NiCoAl-LDHs and improves its hydrophilicity.This provides rapid diffusion channels and more interlayer active sites for chloride ions,achieving high desalination kinetics.A hybrid capacitive deionization(HCDI)cell was assembled using Ar-NiCoAl-LDHs@ACC as the chloride ion removal electrode and activated carbon as the sodium ion removal electrode.This HCDI cell achieved a high desalination capacity of 93.26 mg g-1 at 1.2 V in a 1 000 mg L-1 NaCl solution,a remarkable desalination rate of 0.27 mg g-1 s-1,and a good charge efficiency of 0.97.The capacity retention remained above 85%after 100 cycles in a 300 mg L-1 NaCl solution at 0.8 V.The work provides new ideas for the controlled preparation of two-dimensional metal hydroxide materials with a large interlayer spacing and the design of high-performance electrochemical chlorine ion removal electrodes.