Ultrahigh capacitive deionization performance by 3D interconnected MOF-derived nitrogen-doped carbon tubes

The design of new-family carbon materials to capture more saline ions is one of the biggest challenges of capacitive deionization (CDI) for water desalination. Herein, we demonstrate the preparation of integrated tubular metal-organic framework architectures using a 3D scaffold, and their derivative of nitrogen-doped carbon tubes (denoted as NCTs) that possess a maximum salt adsorption capacity of 56.9 mg g⁻¹ and good cycling stability. Compared with other carbon materials, our elaborately designed NCTs exhibit multiple advantages: (i) tubular architecture diminishes the efficient diffusion distance for both electrons and ions, (ii) binder-free electrode configuration provides increased accessible surface area for ions accommodation, and (iii) plentiful nitrogen dopants improve the reactivity and electrical conductivity of carbon matrix. Consequently, NCTs exhibit an ultrahigh CDI performance compared to other carbon materials reported previously, highlighting the significance of 3D free-standing carbon architectures for CDI application.