Tunable Pseudocapacitive Behavior in Metal–Organic Framework-Derived TiO₂@Porous Carbon Enabling High-Performance Membrane Capacitive Deionization

Abstract

Titanium dioxide (TiO2) composites have shown promise in desalination as electrode materials of capacitive deionization (CDI). However, it remains a significant challenge to explore their pseudocapacitive potential for further enhancement of salt adsorption capacity and long-term stability. Herein, we report a titanium dioxide/porous carbon composite (TiO2@PC) with tunable pseudocapacitance for a high-performance membrane CDI (MCDI) based on a metal–organic frameworks (MOFs)-derived strategy. By controlling the pyrolysis conditions, the crystalline degree and specific surface areas of TiO2@PC samples have been optimized to improve the salt adsorption performance. A synergy of high pseudocapacitance and good oxidation resistance endows the anatase TiO2@PC (annealed at 600 °C) with an improved salt adsorption capacity of 46.7 mg g–1 at 10 mA g–1 and stable cycling performance over 50 cycles. These properties reveal the great potential of anatase TiO2@PC to serve as a promising candidate of electrode materials for MCDI.