Photoelectrochemical cell for water decomposition with a hybrid photoanode and a metal-hydride cathode

Abstract

The operation of a photoelectrochemical cell for hydrogen production by water decomposition under simulated sunlight (a 150 W Xe lamp) with a hybrid photoanode based on a Si solar cell and TiO₂ film as well as with a metal-hydride cathode based on LaNi₅ alloy has been investigated. TiO₂ films were produced by the chemical vapor deposition (CVD) method. A new technique of production of continuous CVD TiO₂ films on semiconductor surface has been proposed. The peculiarity of this technique is a deposition of a thin (30–40 nm) Ti layer on the substrate prior to a TiO₂ deposition. This metal layer serves as the catalyst of following TiO₂ film growth and then it is oxidized to TiO₂. Continuous TiO₂ films obtained by such a way protect the solar cell surface from oxidation in the electrolyte. The optimal TiO₂ film thickness and structure for highest photocurrent have been determined. It has been shown that the use of the metal-hydride cathode based on LaNi₅ alloy instead of a Pt cathode increases significantly (up to 50%) the solar cell efficiency. The photoconversion efficiency attained 2% with the Pt cathode and 3% with the metal-hydride cathode.