In Situ Decorating Coordinatively Unsaturated Fe Sites for Boosting Water Oxidation Performance of TiO 2 Photoanode

Kinetics play a critical role in the photoelectrochemical (PEC) system, whereas co‐catalysis is mainly responsible for reducing the reaction barrier and facilitates water splitting. Here, the unsaturated Fe sites through the metal‐organic framework (MOFs) structure promote the kinetics of water oxidation over TiO 2 are successfully in situ decorated. This heterostructure further helps us to better understand the PEC behaviors of organic–inorganic hybrid systems. MIL‐100(Fe), as the typical MOFs model, is facilely achieved by an FeOOH sacrificial template method, a strategy which could anchor the compact and ultrathin MIL‐100(Fe) films on the surface of TiO 2 to obtain abundant unsaturated Fe sites. The photocurrent density of MIL‐100(Fe)/TiO 2 reaches about 2.4 times at 1.23 V vs reversible hydrogen electrode (RHE) compared with bare TiO 2 , and the incident photon to current conversion efficiency value increases up to 47% (at 390 nm). Furthermore, the photocurrent density of MIL‐100(Fe)/TiO 2 is maintained at 84% after 3 h, showing that the organic component of MIL‐100(Fe) takes a nature of favorable stability. The configuration of MIL‐100(Fe)/TiO 2 will bring a new insight for learning the basic function of unsaturated metal sites in the PEC system.