Light energy accumulation using Ti/RuO2 electrode as capacitor

In the present study, the possibility to use Ti/RuO2 electrode as capacitor for storage of photoelectrons generated under UV irradiation in Ti/TiO2 photoelectrode has been investigated. A light-sensitive TiO2 layer has been formed by means of anodizing Ti electrode in the solution of 0.5 M H2SO4. A layer of RuO2, exhibiting the properties of electrochemical capacitor, has been formed by means of thermal decomposition of RuOHCl3 also on Ti substrate. The photocharging capability of RuO2 has been studied by means of short-circuiting Ti/RuO2 electrode with Ti/TiO2 photoelectrode in deaerated solution of 0.1 M KOH. It has been shown that the intensity of photocurrent flowing from Ti/TiO2 to Ti/RuO2 electrode depends mainly on the potential of the latter. Maximum value of photocurrent density was ∼180 μA cm−2, which corresponded to maximum value of photon-to-electron conversion efficiency (IPCE) of about 60%. The amount of photogenerated charge Q ph, which can be stored, depends on the capacitance of RuO2 coating. Under the conditions of the experiment, Q ph ranged from ∼35 to ∼50 mC, which corresponded to a specific charge of RuO2 coating ranging between ∼20 and ∼30 mAh g−1.