Engineering Ru-anchored metal–organic frameworks in hematite photoanodes for efficient photoelectrochemical water oxidation

Abstract

Hematite (α-Fe₂O₃) thin films exhibit remarkable advantages in photoelectrochemical water splitting (PEC-WS) applications due to their adjustable chemical composition and controllable band gap. However, the typically low efficiency of photogenerated carrier separation hinders their practical applications. This work focuses on regulating the structure of a metal–organic framework (MOF) on the surface of an α-Fe₂O₃ photoanode. Ru atoms are loaded onto MOF-68 to optimize the electronic structure and enhance the PEC-WS performance. The Sn@α-Fe₂O₃/MOF-68/Ru photoanode exhibits an optimal photocurrent density of 1.82 mA cm⁻² at 1.23 V_RHE, representing a 100% enhancement over the pristine α-Fe₂O₃ photoanode. MOF-68 acts as a highly efficient cocatalyst support to promote the uniform anchoring and dispersion of Ru nanoparticles without obvious aggregation. The integration of MOF-68/Ru onto the surface of the α-Fe₂O₃ photoanode facilitates the formation of a heterojunction, which can serve as an additional driving force to effectively suppress photogenerated carrier recombination. The synergistic effect of MOF-68 and Ru can enrich catalytic active sites and promote photogenerated carrier separation and transfer, ultimately accelerating the water oxidation reaction kinetics.