Enhanced photoelectrochemical water splitting efficiency of hematite (α-Fe2O3)-Based photoelectrode by the introduction of maghemite (γ-Fe2O3) nanoparticles

To enhance the photo-electrochemical performance of hematite photo-electrode, we designed a phase junction configuration of alpha and gamma-Fe2O3. By inserting maghemite (gamma-Fe2O3) particles synthesized by reverse micelle deposition, which is for suppressing the phase transition from gamma-Fe2O3 to alpha-Fe2O3, in between a hematite (alpha-Fe2O3) layer and fluorine-doped tin oxide (FTO) substrate, we could achieve a drastic improvement of the current density. We successfully confirmed using Raman spectroscopy that gamma-Fe2O3 still remained after the annealing process performed at high temperature and the phase-junction configuration of alpha/gamma-Fe2O3 was constructed. In addition, we could demonstrate using a time-resolved spectroscopic method and an electro-impedance spectroscopy measurement that the enhancement of the performance originated from the retardation of the recombination, resulting from the improvement of the charge separation efficiency.

Automated summary

By designing a phase junction configuration of alpha and gamma-Fe2O3 in the hematite photo-electrode and using maghemite particles to suppress the phase transition, we significantly improved the current density. The confirmation through Raman spectroscopy of the construction of the alpha/gamma-Fe2O3 phase-junction structure further supports the enhancement of performance.