SrTiO3 thin film photoanodes fabricated by combinatorial chemical beam vapour deposition: intricate connection between elemental composition and thin films' properties

Abstract

In this research, we highlight an innovative combinatorial approach to explore the correlation between the elemental composition of SrTiO₃ thin films and their photoelectrochemical characteristics for water splitting. Employing the Chemical Beam Vapor Deposition technique, we successfully synthesized Sr_xTi_yO_z thin films with varying Sr/Ti compositions, ranging from highly strontium cation deficient (Sr/Ti = 0.3) to rich (Sr/Ti = 2) films, in a single deposition process. A detailed examination of the near-stoichiometric range identified a narrow window wherein the crystalline perovskite structure was maintained. This enabled us to pinpoint the optimal strontium to titanium ratio composition between St/Ti = 0.8 and Sr/Ti = 1.2, resulting in the most efficient photoelectrode. The performance of these photoelectrodes was correlated with the physico–chemical properties of the Sr_xTi_yO_z films, as investigated through techniques such as X-ray diffraction, ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy.