Semiconductive‐Ferroelectric‐Enhanced Photo‐Electrochemistry with Collective Improvements on Light Absorption, Charge Separation, and Carrier Transportation

Abstract The efficiency of photo‐electrochemistry is jointly determined by multiple factors such as light absorption, charge separation, and carrier transportation. It is essential to maximize all of them but has proved challenging especially for photoelectrodes made from wide‐bandgap semiconductors. Here, a conceptually new strategy noted as semiconductive‐ferroelectric‐enhanced photo‐electrochemistry (SF‐PEC) is reported based on a doped TiO 2 ‐Ba x Sr 1− x TiO 3 (BST) core–shell nanowire array. Through an in situ surface conversion and an electron/nitrogen codoping process, a self‐polarized, surface‐amorphized, and doped BST thin layer is created on the surface of TiO 2 , resulting in a semiconductive‐ferroelectric‐enhanced TiO 2 (SF‐TiO 2 ) photoelectrode. Compared with pristine TiO 2 and ferroelectric‐enhanced TiO 2 (F‐TiO 2 ), the SF‐TiO 2 has stronger light absorption, greater charge separation, and faster carrier transportation, which is identified to be a synergistic outcome of the reduced bandgap, moderate ferroelectric polarization, and high carrier density and mobility. The photocurrent density of SF‐TiO 2 reaches 1.87 mA cm −2 at 1.23 V versus reversible hydrogen electrode (RHE), 1.39 and 2.46 times higher than that of F‐TiO 2 and TiO 2 , respectively. The SF‐TiO 2 maintains over 90% of its photocurrent density after being aged in air for 11 months. This work provides new insights to extend the efficiency limit of photo‐electrochemistry.