Lewis-basic PO₄^3- induced interfacial water dissociation on CoWO₄ for enhanced neutral oxygen evolution reaction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Neutral water electrolysis faces challenges due to sluggish oxygen evolution reaction (OER) kinetics and high overpotential, stemming from low hydroxide ion (OH-) concentration.
• Catalyst design for efficient OER requires strategies to accelerate water dissociation and intermediate hydroxyl radical (*OH) generation.
• Lewis base sites on catalyst surfaces can facilitate proton acceptance, promoting HOH bond cleavage and *OH formation.

Purpose of the Study:

• To investigate the effect of incorporating Lewis base phosphate (PO4^3-) into cobalt tungstate (CoWO4) for neutral water electrolysis.
• To enhance the kinetics and stability of the oxygen evolution reaction (OER) by modulating the electronic structure of Co/W active sites.
• To provide insights into catalyst design for efficient and stable neutral water electrolysis.

Main Methods:

• Synthesis of a self-supporting PO4^3--CoWO4 electrode.
• Electrochemical characterization, including overpotential measurements at 10 mA cm^-2 in 1 M phosphate buffer solution (PBS).
• Long-term stability tests over 250 hours.
• Mechanistic studies to understand interfacial water behavior, *OH coverage, and active species leaching.

Main Results:

• The PO4^3--CoWO4 electrode demonstrated outstanding OER performance with a low overpotential of 330 mV at 10 mA cm^-2.
• The catalyst exhibited excellent stability, operating continuously for over 250 hours.
• Mechanistic studies revealed that PO4^3- optimizes interfacial water, facilitates water dissociation, enhances *OH coverage, and suppresses active Co/W species leaching.

Conclusions:

• Incorporation of PO4^3- into CoWO4 synergistically boosts both the activity and stability of neutral water electrolysis.
• The Lewis base PO4^3- effectively regulates the catalyst interface, improving OER performance.
• This work offers valuable strategies for designing advanced catalysts for efficient neutral water electrolysis.