Construction of MIL-88(Fe) derived MOF/TiO2 photoanode for efficient photoelectrochemical water splitting

Developing efficient photoanodes for water oxidation is highly promising due to their critical role in producing green H 2 and harnessing solar energy. Herein, a metal-organic framework (MOF)/photoanode was successfully constructed by coating TiO 2 nanorods with MIL-88(Fe) MOF for photoelectrochemical (PEC) water splitting. The results demonstrated that MIL-88(Fe) was uniformly and tightly coated on TiO 2 and functioned as a cocatalyst. The MIL-88(Fe) MOF provides a large surface area and more Fe-O active sites, contributing to high PEC activity by reducing electron/hole recombination and enhancing light response capability. Moreover, the photoanode also exhibited an improved charge conductivity. As a result, the MIL-88(Fe)/TiO 2 photoanode exhibited an excellent photocurrent density of 1.06 mA cm −2 at 1.23 V RHE , which is approximately 2.6 times higher than the pristine TiO 2 . Charge transfer kinetics analyses and electrochemical tests were carried out and revealed that the improved PEC performance was attributed to the introduction of MIL-88(Fe), which promoted charge separation-transfer. This research provided new insights into the design of efficient semiconductor/MOF composite photoanodes for PEC water oxidation.