Titanium disulfide decorated hollow carbon spheres towards capacitive deionization

Abstract

Freshwater scarcity in conjunction with population expansion puts human survival in doubt. Throughout the world, millions of people are deprived of clean and safe drinking water. The development of novel technologies to desalinate water is among the most valuable studies for humanity. Receiving benefits from low energy consumption, high environmental capability, and low-production cost, capacitive deionization (CDI) received significant attention in saline water desalination. Rational design of efficient electrode materials by tailoring their structural and compositional properties, therefore, plays a pivotal role in achieving high-performance CDI systems. Hollow carbon spheres (HCSs) with high specific surface area (SSA) and reasonable pore size distribution are highly promising as electrode materials in developing high-performance CDI systems. However, the low electrosorption capacity of HCSs is one of the major obstacles in front of their practical application in CDI technology. Decoration of HCSs with transition metal compounds can be used to address the wettability issue of HCSs and enhance their electrosorption capacity by incorporating Faradic characteristics, which are the major drawbacks of carbonaceous materials. Herein, HCSs are integrally decorated with titanium disulfide (TiS2) through a “sol-gel” assisted route. Electrochemical behavior and CDI performance of the TiS2@HCSs were evaluated. In addition to wettability improvement, ion transfer into the hollow cavities and mesoporous structure of carbonaceous shells are also enhanced by TiS2-decoration of HCSs. Besides, TiS2@HCSs showed significant salt adsorption capacity (18.0 mg g−1) and electrosorption rate. This can be attributed to the synergistic effects between the high surface area and mesoporous structure of HCSs, and the higher wettability and intercalation properties of TiS2. The TiS2-decorated HCSs also showed excellent cycle stability and kept 87% of their initial salt adsorption capacity after 65 cycles. These results demonstrate the potential capability of TiS2@HCSs in practical CDI applications.