Atomic layer deposition of TiO₂ on carbon-nanotube membranes for enhanced capacitive deionization

Capacitive deionization (CDI) is an energy-efficient and environment-benign process to produce fresh water. Carbon nanotubes (CNTs) are promising building blocks in constructing high-performance CDI electrodes. Nevertheless, the strong hydrophobicity of CNTs significantly impedes their applications in aqueous environment. Herein, hydrophilic CNT-based membrane electrodes are obtained via atomic layer deposition (ALD). We demonstrate, for the first time, that ALD is an efficient and flexible means of enhancing the CDI performance of free-standing CNT membrane electrodes by depositing TiO₂ nanoparticles on the surface of CNTs. The CNT membranes display preferable electrosorption behavior after moderate ALD cycle numbers and stable reusability in the desalination process.