Controllable synthesis of Na, K-based titanium oxide nanoribbons as functional electrodes for supercapacitors and separation of aqueous ions

Abstract

Rechargeable capacitive electrode materials have attracted increasing interest due to the fast electrochemical charge/discharging processes, good operational safety, and long cycling life. Ti-based materials are significant typical electrode materials for emerging applications as supercapacitors and for capacitive deionization with a relatively low cost and good electrochemical stability. Traditional commercial materials are currently blocked and easily agglomerated at the micro–nanoscale, which imposes structural limitations on the electrochemical and desalination performance. We report a facile preparation for the controllable synthesis of different Ti-based oxides with alkali ion (Li, Na, and K) nanoparticles, which were synthesized by employing an organic sol–gel method and calcination. Na, K-Ti oxides possessed dispersed crystal whisker structures with the form of ordered morphological nanoribbons. KTO had excellent electrochemical performance in terms of the capacitance and good rate capability, owing to its structural stability and enlarged nano-layer. Further practical applications of the asymmetric systems showed that the KTO//AC device had excellent electrochemical performance with the potential expanded to 1.6 V and showed a selective deionization for KCl solution and heavy ions of Ni²⁺. These designed functional series of Ti-based materials with desirable morphological features will promote chemical preparation methodology, and the fabricated electrode materials can expand the guidelines for incremental development in both energy and environmental research.