Capacitive heavy metal ion removal of 3D self-supported nitrogen-doped carbon-encapsulated titanium nitride nanorods via the synergy of faradic-reaction and electro-adsorption

Recently, the highly efficient, low-cost and environment-friendly capacitive deionization (CDI) hold great promise in the field of wastewater purification. In this paper, we report an N-doped carbon nanolayer (N-C) encapsulated ultrafine titanium nitride (TiN) nanorod-assembled flower-like framework anchored on the carbon cloth (CC) matrix (N-C@TiN@CC) as the self-supported electrode for robust CDI-based heavy metal ion wastewater purification. Benefitting from the synergistic effects of specific structure features (i.e., high porosity, 3D open framework and hierarchical pore arrangement), surface doping strategy of high-conductivity carbon nanolayer and integrated electrode processing, the resultant N-C@TiN@CC hybrid electrode proves superior deionization performance and excellent cycling stability, yielding an outstanding average removal efficiency up to ca. 98 % in the simulated high-concentration single, binary and multi-component wastewater systems. Moreover, it is further revealed the effective electro-adsorption and faradic reaction coupling ion removal process in the deionization system, which may account for the significant removal efficiency promotion of NC@TiN@CC hybrid electrode.