Ultra-durable and highly-efficient hybrid capacitive deionization by MXene confined MoS₂ heterostructure

Capacitive deionization (CDI) is an emerging desalination technology, offering an advisable route to fetch clean water due to its low energy consumption and environmental friendliness. Hybrid CDI (HCDI), proceeding through a faradic ion storage mechanism, is thought as the next generation of CDI due to its high desalination capacity and charge efficiency. However, current HCDI system is plagued by its low desalination rate and poor long-term stability due to the structural instability of the faradic materials. Herein, we developed an effective strategy via combining 2D MoS₂ nanoflakes with 2D MXene to construct a 3D “mutually supported” network architecture, in which MoS₂ nanoflakes could act as the “pillar” of the intrinsic structure of MXene, while MXene could offer structural reinforcement to prevent the structural agrgregation and enhance the electrical conductivity of the heterostructure. As a result, the HCDI system based on MoS₂/MXene heterostructure electrode displays an outstanding desalination performance with a high desalination capacity of 23.98 mg g⁻¹, outstanding desalination rate of 4.6 mg g⁻¹ min⁻¹ and superior cycling stability with only 4% desalination capacity degradation for over 100 cycles, indicating that our strategy should be a promising approach to achieve highly efficient HCDI.