Electrochemical synthesis and characterization of titanium oxide thin films on covalent polyphenylene-modified gold electrodes as electrode materials for supercapacitor applications

[Display omitted] •Titanium oxide is prepared by electrochemical reduction ofTiCl4on diazonium-generated polyphneylene (PPh).•The electrolyte composition and the anion of the supporting salt play a key role on the formation of the titanium oxide film.•PPh/TiO2-400 film shows a high specific capacitance of 438.7 F/g at a current density of 0.5 A g−1 and good stability. Titanium dioxide (TiO2) is one of the technologically conspicuous materials with a wide range of applications including photocatalysts, waste water treatment and energy storage devices. Here, we report a facile method for the synthesis of TiO2 for supercapacitors. Titanium oxide film was prepared by electrochemical reduction of TiCl4 in oxygen-saturated non-aqueous acetonitrile solution containing tetrabutylammonium perchlorate (TBAClO4), and the cathodic deposition process of metal oxide film on modified and bare gold electrodes was estimated by detailed voltammetric analysis. The modified gold electrodes were achieved by formation of polyphenyl (PPh) organic film on gold via electrochemical reduction of benzene diazonium salt. The resulting Au/PPh/TiOx electrode was subjected to thermal annealing at 400 °C, and then the capacitive performance of Au/PPh/TiO2-400 electrode was evaluated by using electrochemical techniques. Compared to the obtained Au/PPh, Au/TiOx and Au/PPh/TiOx electrodes, Au/PPh/TiO2-400 electrode showed a high specific capacitance of 438.7 F/g at a current density of 0.5 A/g and good stability with a capacitance retention of 95 % after 2500 cycles. Moreover, the assembled asymmetric Au/PPh/TiO2-400//RGO:CB/Au device delivered a maximum energy density of 16.4 Wh kg−1 at a power density of 499.9 W kg−1.