In situ polymerized porous Ti3C2Tx/PANI as an electrode material for enhanced desalination performance in asymmetric capacitive deionization†

Capacitive deionization (CDI) has emerged as a sustainable technology for water desalination due to its low energy consumption and environmental compatibility. MXenes are promising CDI electrode materials owing to their hydrophilicity, metallic conductivity, and surface redox activity. However, the strong interlayer van der Waals forces between Ti₃C₂T_x layers lead to severe self-restacking, thus decreasing the desalination performance. Herein, a porous Ti₃C₂T_x/polyaniline (PANI) composite material synthesized through in situ polymerization achieves a remarkable salt adsorption capacity (SAC) of 32.06 mg g⁻¹ in 500 mg L⁻¹ NaCl solution, surpassing pristine Ti₃C₂T_x by 78%. Polyaniline can effectively reduce the self-stacking effect of Ti₃C₂T_x, increase its exposed active sites, and improve the stability and conductivity of Ti₃C₂T_x through the addition of polyaniline, thereby enhancing its salt adsorption capacity and rate in capacitive deionization technology. This work provides a rational design strategy for MXene-based composites toward high-performance CDI systems.