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

Abstract

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.