Constructing iron-group doped metal–organic framework films on hematite photoanodes for efficient solar water splitting

Hematite (α-Fe 2 O 3 ) is considered a highly promising candidate material for photoelectrochemical water splitting (PEC-WS) due to its suitable band gap and band edge location. Nevertheless, enhancing PEC-WS performance through the surface construction of low-cost, highly efficient, and stable electrocatalysts still remains a challenge. This work presents a facile strategy to fabricate α-Fe 2 O 3 photoanodes modified with the metal–organic framework films doped with iron-group elements (Fe, Co, and Ni), which forms abundant active sites and leverage bimetallic synergistic effects. The optimal photocurrent density of FTO/Sn@α-Fe 2 O 3 /MIL-125/Co photoanode achieves 1.97 mA/cm 2 at 1.23 V RHE , which is 2.3 times that of the pure α-Fe 2 O 3 photoanode. The on-set potential exhibits a cathodic shift of 0.1 V. The MIL-125 catalyst with Co doping exhibits the most excellent PEC-WS performance among the three dopants (Fe, Co, and Ni), which can be primarily attributed to more abundant active sites, the lower photogenerated carrier recombination, and the enhanced charge separation and transfer efficiency. Graphical Abstract