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.