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 TiO2 nanorods with MIL-88(Fe) MOF for photoelectrochemical (PEC) water splitting. The results demonstrated that MIL-88(Fe) was uniformly and tightly coated on TiO2 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)/TiO2 photoanode exhibited an excellent photocurrent density of 1.06 mA cm(-2) at 1.23 VRHE, which is approximately 2.6 times higher than the pristine TiO2. 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.