Gradient FeO(x)(PO4)(y) layer on hematite photoanodes: novel structure for efficient light-driven water oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Hematite (Fe2O3) is a promising material for photoelectrochemical (PEC) water oxidation.
• However, its practical application is hindered by low efficiency.

Purpose of the Study:

• To enhance the efficiency of hematite-based photoelectrochemical water oxidation.
• To develop a stable, gradient-structured surface layer for improved performance.

Main Methods:

• Fabrication of a gradient-structured FeOx(PO4)y layer on hematite films via low-temperature phosphate incorporation.
• Characterization using X-ray photoelectron spectroscopy (XPS) depth profiling and X-ray absorption spectroscopy (XAS).

Main Results:

• Formation of a ~50 nm overlayer with a gradient phosphorus distribution and structural evolution.
• Achieved an 8.5-fold enhancement in photocurrent density at 1.23 V vs. RHE.
• Demonstrated applicability across various hematite morphologies and preparation methods.

Conclusions:

• The gradient-structured phosphate layer significantly boosts PEC water oxidation efficiency.
• Enhanced performance is attributed to improved photogenerated electron-hole pair separation via increased hole diffusion length.
• Presents a simple, universal strategy for improving hematite photoanodes.