Two-Dimensional Hetero-structured TiO<sub>2</sub>/TiS<sub>2</sub> Nanosheets for Capacitive Deionization
Zhengqu Yang, Peiyu Yang, Xiaochen Zhang, Haoyuan Yin, Fei Yu, Jie Ma
Abstract
Capacitive deionization (CDI) is a low-cost, low-energy desalination technology, which is largely affected by electrode materials. Both TiO 2 and TiS 2 have good sodium storage capacity, however, TiO 2 has poor electrical conductivity, and TiS 2 has a strong stacking tendency. In this work, a typical transition metal carbide MXene (Ti 3 C 2 T x ) was used as the precursor to prepare hetero-structured TiO 2 /TiS 2 by the hydrothermal method. The rough particles between the layers provided a channel for the rapid transport of sodium ions and relieve the stacking state of nanosheets. The maximum desalination capacity of the TiO 2 /TiS 2 electrode was 36.45 mg g –1 (NaCl), and the capacity retention rate was about 75% after 30 cycles. Based on the electrochemical quartz crystal microbalance, the migration behavior of ions in the desalination process was exhibited in situ. This work shows that TiO 2 /TiS 2, as a heterojunction material obtained from MXene, offers a new idea to solve the problem of poor electrochemical properties of TiO 2 .