TiO2 sol–gel spray method for carbon electrode fabrication to enhance desalination efficiency of capacitive deionization

• We fabricated carbon electrode using TiO2 to enhance the desalination efficiency of CDI.
• The TiO2 coated electrode exhibited excellent desalination efficiency.
• The enhancement of efficiency was attributed to the increase of the wettability of electrode.

Capacitive deionization (CDI),which is an ion removal technology using electro ad/desorption, has attracted much attention as an alternative to conventional desalination due to its eco-friendly and low energy consumption process. Carbon materials were actively employed as an electrode material for CDI and further treated with various methods such as acid/alkali treatments and the addition of organic/inorganic materials to enhance its desalination efficiency. The present study reports a new fabrication method for a carbon electrode to enhance CDI desalination efficiency. A highly durable TiO2 coated carbon electrode, on which a TiO2 coating layer was well dispersed, was fabricated with the sol–gel spray method on a carbon electrode. This TiO2 coated electrode showed approximately two times higher desalination efficiency than the carbon electrode itself in a CDI performance test although the specific capacitance of the TiO2 coated electrode was not significantly different from that of the carbon electrode. This enhanced desalination efficiency was attributed to the facile accessibility of water and ions from bulk solution to the electrode surface because of the high wettability of the TiO2 coated electrode.