Influence of Surface Potential on the Capacitive Performance of the TiO₂ Thin-Film Electrode with Different...

Electrochemical capacitor and capacitive deionization store energy through the interface layer formed between electrodes and electrolytes. The crystalline form and surface potential of the oxide electrode can be changed in order to improve the capacitance. By characterizing the surface property and crystalline form of the TiO₂ thin-film electrode at different sintering temperatures, it is showed that each electrode has its own surface potential which is affected by the crystalline structure. At elevated sintering temperature, TiO₂ transfers from anatase to rutile with an increased surface potential. The electrochemical tests show that the electrode capacitance increases from 19.50 to 41.82 mF/cm². Therefore, rutile TiO₂ has a higher surface potential and better capacitive performance when used on a positive electrode compared with anatase TiO₂. In general, the relation between the surface potential, the crystalline forms, and the capacitive performance is achieved in this work. We hope it can promote the investigation of oxide materials in the application for electrochemical capacitors and capacitive deionization.