Titanium Dioxide Nanocluster Modified Lignite-Based Nanoporous Carbon for Capacitive Deionization

With the development of capacitive deionization (CDI) technology, low-cost and high-performance capacitive deionization electrode materials have received great attention. Herein nanoporous carbon (NPC) was prepared using lignite as the carbon source in this work. The as-prepared NPC has a hierarchical nanoporous structure with micro-, meso- and macro-sized pores. Its specific surface area can reach 3581 m² g⁻¹. Then TiO₂ nanoclusters modified NPC composites were fabricated for better CDI performance due to their synergistic electrochemical behaviour and properties. The results show that the size of TiO₂ nanoclusters is 3–5 nm. TiO₂ nanoclusters are uniformly dispersed in the composites which retain the hierarchical nanoporous structure and possess high specific surface area up to 3703 m² g⁻¹. Compared with NPC, the performance of xTiO₂@NPC was significantly improved. The specific capacitance of 10TiO₂@NPC is 193.45 F g⁻¹ with 95% capacity retention after 5000 cycles. Its CDI adsorption capacity is up to 11.23 mg g⁻¹, which is 1.55 times of NPC (7.24 mg g⁻¹). It provides promising candidate materials for low-cost, industrial CDI applications with high performance through a facile method.