A Bifunctional Ferroelectric Catalyst Enabling Simultaneous Photoelectrochemical Water Oxidation and Two-Electron...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Photoelectrochemical (PEC) systems offer sustainable chemical synthesis by combining light and electrical energy.
• External field modulation is an emerging strategy to control PEC reactions, complementing traditional material property tuning.

Purpose of the Study:

• To investigate the use of a bifunctional ferroelectric catalyst, Barium Strontium Titanate (Ba$_{0.7}$Sr$_{0.3}$TiO$_{3}$ or BSTO), for enhancing both water oxidation and two-electron oxygen reduction reactions (2e$^{-}$ORR).
• To demonstrate the efficacy of ferroelectric polarization in modulating interfacial properties for improved PEC performance.

Main Methods:

• Utilized BSTO as a coating on metal oxide photoanodes (α-Fe$_{2}$O$_{3}$, TiO$_{2}$, BiVO$_{4}$) and as a cathode material.
• Employed controlled electric poling to induce ferroelectric polarization.
• Conducted mechanistic studies to analyze band bending and charge separation at interfaces.
• Investigated the effect of polarization on oxygen adsorption configurations and reaction pathways.

Main Results:

• BSTO-coated α-Fe$_{2}$O$_{3}$ photoanodes showed enhanced PEC water oxidation performance due to polarization-induced band bending and improved charge separation.
• The strategy was validated with other photoanodes like TiO$_{2}$ and BiVO$_{4}$.
• On the cathode, ferroelectric polarization shifted O$_{2}$ adsorption, accelerating charge transfer and favoring the 2e$^{-}$ORR pathway, leading to higher H$_{2}$O$_{2}$ production.

Conclusions:

• Ferroelectric polarization is a versatile external field modulation strategy for optimizing (photo)electrocatalytic systems.
• BSTO acts as a bifunctional catalyst, enhancing both water oxidation and 2e$^{-}$ORR for sustainable chemical production.