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

Summary In this paper, titanium dioxide (TiO 2 ) nanoparticles were employed as catalysts towards V 2+ /V 3+ redox couple of vanadium redox flow battery (VRFB). The effect of TiO 2 phase on the electrocatalytic performance for negative couple was systematically investigated. The electrochemical properties of TiO 2 with different phase were assessed via cyclic voltammetry and electrochemical impedance spectroscopy by using AB as conductive agent. Obtained from the results, anatase TiO 2 (α-TiO 2 ) exhibits superior electrocatalytic activity to rutile TiO 2 (γ-TiO 2 ). The VRFB cell performs well at discharge capacity, voltage efficiency, and energy efficiency by employing α-TiO 2 -modified negative electrode with current density varying between 50 and 100 mA cm −2 . The discharge capacity of α-TiO 2 -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 α-TiO 2 . Experimental results show that TiO 2 is an ideal catalyst for VRFB. Moreover, α-TiO 2 demonstrates superior electrocatalytic performance to γ-TiO 2 towards V 2+ /V 3+ reaction.