Flexible ultrathin Nitrogen-Doped carbon mediates the surface charge redistribution of a hierarchical tin disulfide nanoflake electrode for efficient capacitive deionization.

ABSTRACT

Constructing pseudocapacitive electrodes with high specific capacities is indispensable for increasing the large-scale application of capacitive deionization (CDI). However, the insufficient CDI rate and cycling performance of pseudocapacitive-based electrodes have led to a decline in their use due to the corresponding volumetric expansion and contraction that occurs during long-term CDI processes. Herein, hierarchical porous SnS2 nanoflakes are encapsulated inside an N-doped carbon (NC) matrix to achieve efficient CDI. Benefiting from the synergistic properties of the pseudocapacitive SnS2 nanoflakes and few-layered N-doped carbon, the heterogeneous interface simultaneously provides more available vigorous sites and demonstrates rapid charge-transfer kinetics, resulting in a superior desalination capability (49.86 mg g-1 at 1.2 V), rapid desalination rate (1.66 mg g-1 min-1) and better cyclic stability. Computational research reveals a work function-induced surface charge redistribution of the SnS2@NC heterojunction, which can lead to an auspicious surface electronic structure that reduces the adsorption energy to improve the diffusion kinetics toward sodium adsorption. This work contributes to providing a thoughtful understanding of the interface engineering between transition metal dichalcogenides and NC to construct high-performance CDI electrode materials for further industrialization.