Structural, optical, and photo-electrochemical properties of Aurivillius-type layered Bi4Ti3O12–BiFeO3 oxides

Photo-electrochemical cells (PECs) represent one of the most promising technologies today for storing sun energy as chemical bonds (solar fuels), exploiting carbon dioxide as a starting reagent. However, identifying suitable photoelectrodes remains a challenging and open issue. In this work, the possibility of using Aurivillius-type compounds to produce solar fuels was deeply investigated. Aurivillius-type perovskites, with general formula Bi(n+1)Fe(n-3)Ti3O(3n+3) (BFTO-n), were synthesized and fully characterized to study the influence of the number of perovskite layers and the synthesis parameters on their final properties. Specifically, eight different systems were considered increasing the amount of iron and, consequently, the number of perovskite layers. These compounds were synthesized through both a standard solid-state reaction method and a sol-gel technique. For each system, a screen printing ink was formulated to be deposited as photo-electrodes onto transparent conducting supports, and their morphological (XRD and SEM analysis) electrochemical and photo-electrochemical properties (cyclic and linear voltammetry, impedance, Mott-Schottky analysis) were determined. The obtained results demonstrate the potentiality of Aurivillius-type compounds as innovative materials for carbon dioxide photo-electrochemical reduction.