Electrocatalytic performance of TiO2 with different phase state towards V2+/V3+ reaction for vanadium redox flow battery

In this paper, titanium dioxide (TiO2) nanoparticles were employed as catalysts towards V2+/V3+ redox couple of vanadium redox flow battery (VRFB). The effect of TiO2 phase on the electrocatalytic performance for negative couple was systematically investigated. The electrochemical properties of TiO2 with different phase were assessed via cyclic voltammetry and electrochemical impedance spectroscopy by using AB as conductive agent. Obtained from the results, anatase TiO2 (alpha-TiO2) exhibits superior electrocatalytic activity to rutile TiO2 (gamma-TiO2). The VRFB cell performs well at discharge capacity, voltage efficiency, and energy efficiency by employing alpha-TiO2-modified negative electrode with current density varying between 50 and 100 mA cm(-2). The discharge capacity of alpha-TiO2-modified cell with vanadium ion concentration of 1.6 M comes up to 113.5 mA h at 100 mA cm(-2) current density, which is increased by 39.1 mA h after modification for negative electrode. Moreover, the corresponding energy efficiency increases by 7.5% after modification of alpha-TiO2. Experimental results show that TiO2 is an ideal catalyst for VRFB. Moreover, alpha-TiO2 demonstrates superior electrocatalytic performance to gamma-TiO2 towards V2+/V3+ reaction.