Modular Solar-to-Fuel Electrolysis at Low Cell Potentials Enabled by Glycerol Electrooxidation and a Bipolar Membrane...

Area of Science:

• Electrochemistry
• Renewable Energy
• Catalysis

Background:

• Solar fuel generation is often limited by the high potential required for the oxygen evolution reaction (OER).
• Glycerol electrooxidation reaction (GEOR) presents a promising alternative anodic pathway, utilizing a renewable byproduct from biodiesel synthesis.
• Developing efficient electrocatalysts and cell designs is crucial for advancing sustainable energy technologies.

Purpose of the Study:

• To investigate the potential of glycerol electrooxidation (GEOR) as an alternative anodic reaction for solar fuel generation.
• To evaluate the performance of a ternary metal electrocatalyst (Au-Pt-Bi) for GEOR in alkaline crude glycerol solutions.
• To demonstrate cell potential reductions when GEOR is paired with reduction reactions using a bipolar membrane (BPM) separator.

Main Methods:

• Electrochemical characterization of an Au-Pt-Bi ternary metal electrocatalyst.
• Testing GEOR in a model alkaline crude glycerol solution.
• Integration of GEOR with reduction reactions (hydrogen evolution and CO2 reduction) using a bipolar membrane (BPM) separator.
• Long-term stability testing of the electrochemical cell.

Main Results:

• GEOR on the Au-Pt-Bi catalyst significantly lowered the cell potential by 1 V compared to OER at 10.0 mA cm⁻².
• The observed voltage reduction remained stable for up to 80 hours of operation.
• Minimal glycerol crossover was detected through the bipolar membrane, indicating efficient separation.
• The system demonstrated effective pairing with both hydrogen evolution and CO2 reduction cathodes in seawater and acidic catholytes.

Conclusions:

• Glycerol electrooxidation, coupled with a bipolar membrane, offers a substantial improvement in solar fuel generation efficiency by reducing cell potential.
• The Au-Pt-Bi ternary catalyst demonstrates high performance and stability for GEOR.
• These findings pave the way for novel, high-performance cell designs in integrated photoelectrochemical solar fuel systems.