Fe Coordination Environment Modulating Oxygen Evolution Reaction Properties of Cobalt Site

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Cobalt-iron layered double hydroxides (LDHs) show promise for oxygen evolution reaction (OER).
• Understanding the precise role of iron and its mechanism in promoting OER remains a challenge.
• Identifying the performance-determining site (PDS) is crucial for catalyst optimization.

Purpose of the Study:

• To design and investigate Co-Fe bimetallic silicate hydroxides for high-efficiency OER catalysis.
• To distinguish the effects of different iron coordination states (Fe3+ (Oh) and Fe3+ (Td)) on OER performance.
• To elucidate the mechanism by which Co-Fe interactions promote OER and identify the PDS.

Main Methods:

• Synthesis of Co-Fe bimetallic silicate hydroxides with tunable iron coordination.
• Electrochemical characterization of OER activity and stability.
• Density Functional Theory (DFT) calculations to investigate electronic structures and reaction mechanisms.

Main Results:

• Designed Co-Fe bimetallic silicate hydroxides exhibit enhanced OER performance.
• Fe3+ (Oh) positively modulates adjacent cobalt sites, while Fe3+ (Td) has an inhibitory effect.
• A significantly reduced overpotential of 254 mV at 10 mA cm-2 was achieved.
• DFT identified Co2+ as the PDS and elucidated the underlying electronic mechanisms.

Conclusions:

• Different iron coordination environments in Co-Fe bimetallic silicate hydroxides distinctly influence OER catalysis.
• The study successfully identified the PDS and clarified the synergistic mechanism of Co-Fe bimetallic effects in OER.
• This work provides valuable insights for designing advanced OER electrocatalysts and resolving mechanistic controversies.