Enhanced cycling stability of capacitive deionization via effectively inhibiting H₂O₂ formation: The role of nitrogen dopants

Capacitive deionization (CDI) is an emerging water desalination technique that holds great potential in solving the global water shortage issue. It is known that, H₂O₂ formation at the cathode interface causing the performance degradation of activated carbons (ACs) electrode has limited the large-scale implementation of CDI, but up to date there has seldom any effective solution being reported. In this work, we proposed the use of nitrogen-doped carbon spheres (NCSs)-based CDI cathode instead of that made up of activated carbons (ACs). Benefited from the enhanced oxygen reduction ability offering by the abundant active nitrogen dopants, the asymmetrical apparatus assembled by NCSs cathode and ACs anode exhibits an enhanced cycling stability with a retention ratio of 79.6% even after 50 cycles, which surpasses that of symmetrical apparatus (only 18%). This work provides a simple and effective approach to improve the cycling stability of CDI, highlighting the significance of surface nitrogen-doping modification and the importance of interfacial electrochemistry at the nanoscale.