Fe-Co dual-sites p-d orbital hybridization: Electronic restructuring for accelerated oxygen evolution kinetics.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Sluggish oxygen evolution reaction (OER) kinetics hinder efficient water electrolysis for hydrogen production.
• Density Functional Theory (DFT) calculations guide catalyst design for improved reaction kinetics.

Purpose of the Study:

• To engineer a dual-site catalyst (Fe-CoS2/Ni3S4) for enhanced oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) kinetics.
• To optimize p-d orbital hybridization and dynamic surface reconstruction for improved electrocatalyst performance and stability.

Main Methods:

• Density Functional Theory (DFT) calculations for catalyst design.
• Synthesis of Fe-CoS2/Ni3S4 dual-site catalysts.
• Operando analyses to study reaction mechanisms and electronic structure.
• Electrochemical testing for water splitting performance (HER and OER overpotentials, cell voltage).
• Stability tests to assess metal dissolution and activity retention.

Main Results:

• Fe-CoS2/Ni3S4 catalysts exhibit synergistic optimization of p-d orbital hybridization via Co3+ and Fe3+ centers.
• Co3+ sites facilitate OOH* desorption, reducing Gibbs free energy by 0.94 eV.
• Fe-induced electron delocalization lowers intermediate coupling barriers.
• Dynamic reconstruction generates metastable Co3+ species with optimized eg orbital occupancy.
• Achieved ultralow overpotentials: 156 mV for HER and 230 mV for OER at 50 mA cm-2.
• Overall water splitting at 1.48 V for 10 mA cm-2.
• Suppressed metal dissolution (<12% after 20 h) with 89.2% activity retention.

Conclusions:

• The engineered dual-site catalyst demonstrates a dual-regulation strategy for efficient water electrolysis.
• Atomic-level orbital engineering and dynamic surface reconstruction are key for optimizing OER intermediates and HER-active phase stabilization.
• This approach provides a paradigm for designing robust bifunctional electrocatalysts for sustainable energy applications.