Porous versus Compact Nanosized Fe(III)-Based Water Oxidation Catalyst for Photoanodes Functionalization

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Integrated absorber/electrocatalyst designs in photoelectrodes offer component optimization but face challenges like parasitic light absorption and junction complexities.
• Developing efficient electrocatalysts that are transparent to visible light and minimize parasitic absorption is crucial for advancing photoelectrochemical cells.

Purpose of the Study:

• To fabricate and evaluate a porous iron(III) oxide nanoparticle-assembled coating as a transparent electrocatalyst for water oxidation.
• To investigate the impact of this porous catalyst morphology on the performance of crystalline hematite photoanodes.

Main Methods:

• Pulsed-laser deposition technique was employed to create a porous iron(III) oxide nanoparticle coating.
• Fabricated photoanodes were characterized using photoelectrochemical measurements and photoelectrochemical impedance spectroscopy.

Main Results:

• The porous iron(III) oxide catalyst coating was transparent to visible light and active for water oxidation.
• Compared to compact morphologies, the porous catalyst significantly improved photoanode performance, reducing photocurrent overpotential by ~200 mV and increasing photocurrent 5-fold at 1.23 V vs. RHE.
• Photoelectrochemical impedance spectroscopy revealed increased trapped surface hole capacitance and decreased charge transfer resistance, suggesting an adaptive junction.

Conclusions:

• Porous nanostructured electrocatalysts can form adaptive junctions with photoabsorbers, overcoming parasitic absorption issues.
• The fabricated porous iron(III) oxide coating represents a highly effective strategy for enhancing photoelectrochemical water oxidation efficiency.