Successive performance enhancement on a Ge-Ti codoped α-Fe2O3 with AlOOH modification photoanode for photoelectrochemical water splitting.

[Display omitted] • Ge-Ti codoping synergisticly suppresses bulk and surface charge in the Fe 2 O 3 photoanodes. • AlOOH modification elevates the flat-band potential and enhances charge separation. • Secondary growth layer and NiFeO x cocatalyst effectively reduce onset potential. • Photocurrent density of 3.46 mA cm−2 at 1.23 V RHE and ABPE of 0.51% were achieved. • The Cat/Al/SG/Ge-Ti shows long-term stability of less than 10% decay after 20 h. The poor charge separation efficiency is the main limiting factor of the α-Fe 2 O 3 photoanode for photoelectrochemical water splitting. In this study, we have discovered that the incorporation of Ge-Ti codoping and AlOOH modification strategies can greatly enhance the charge separation efficiency of the α-Fe 2 O 3 photoanode. By introducing the Ti element, which possesses high conductivity, and further enhancing the charge transfer through Ge doping, we have achieved a synergistic inhibition of charge recombination in the Ge-Ti codoped α-Fe 2 O 3. Additionally, the introduction of AlOOH through modification has led to an increase in the interface band bending, thereby enhancing charge separation by elevating the Fermi band level. Furthermore, through the secondary growth (shorted as SG) of undoped α-Fe 2 O 3 and the incorporation of a NiFeO x cocatalyst, we have successfully adjusted the surface states and reduced the onset potential. Through the collaborative efforts of Ge-Ti codoping, SG, AlOOH modification, and NiFeO x catalysis, we have sequentially optimized the performance of the α-Fe 2 O 3 -based photoanode, resulting in an impressive photocurrent density of 3.46 mA cm−2 at 1.23 V RHE , as well as a low onset potential of 0.65 V RHE. [ABSTRACT FROM AUTHOR]