α-Fe2O3 is considered as one of the most suitable materials for photoelectrochemical (PEC) water oxidation due to its appropriate band gap energy, band positions, and abundance. However, the short hole diffusion length (2-4 nm) of α-Fe2O3 is a long-term problem to be solved. Here, a core-shell-structured ultrathin α-Fe2O3 on mesoporous WO3 photoanode was fabricated by atomic layer deposition (ALD) to achieve minimal charge recombination, which is the main reason for the lower PEC performance of α-Fe2O3. A facile drop-casting method was adopted to produce mesoporous WO3 scaffolds, and the subsequent ALD process formed uniform and ultrathin α-Fe2O3 layers that act as both light absorption and protective layers. The ultrathin α-Fe2O3 layer with a thickness of only ∼8 nm on mesoporous WO3 scaffolds has been proven to achieve a reasonable photocurrent density, which originates mainly from enhanced light absorption and minimized charge recombination. The PEC performance of the as-fabricated m-WO3/Fe2O3 photoanode was measured, and the effect of an oxygen evolution cocatalyst (OEC) and a TiO2 overlayer on the performance was also studied. Consequently, the photoanode with ∼8 nm thick α-Fe2O3 showed an ∼4 mA/cm2 photocurrent density at 1.6 V vs reversible hydrogen electrode (RHE) under 1 sun illumination.
Bibliographical noteFunding Information:
This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT and Future Planning (NRF-2018K1A3A1A32055268, 2019R1A2C3009157, NRF-2019M3E6A1064525, NRF-2019M1A2A2065612).
Copyright © 2020 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Renewable Energy, Sustainability and the Environment