Energy-Efficient Hydrogen Evolution by Fe-S Electrocatalysts: Mechanistic Investigations

Area of Science:

• Inorganic Chemistry
• Electrochemistry
• Catalysis

Background:

• Hydrogen evolution reaction (HER) is crucial for clean energy.
• Developing efficient catalysts for HER is a key research area.
• Iron-sulfur (Fe-S) complexes show potential as HER catalysts.

Purpose of the Study:

• Investigate the catalytic properties of a Fe-S complex for H2 evolution.
• Analyze the mechanisms of catalysis in various acidic media.
• Compare the efficiency of different catalytic pathways.

Main Methods:

• Electrochemical measurements to determine catalytic potentials.
• Density Functional Theory (DFT) calculations for thermodynamic and kinetic analysis.
• Spectroscopic and electroanalytical simulations to elucidate reaction mechanisms.

Main Results:

• Fe-S complex catalyzed H2 evolution at -1.16 V (vs Fc+/Fc) with trifluoromethanesulfonic acid (HOTf) and -1.57 V with trifluoroacetic acid (TFA).
• Anilinium acid initiated a proton-coupled electron transfer (PCET) pathway, distinct from stepwise CCE/CE mechanisms observed with HOTf/TFA.
• PCET pathway enhanced heterogeneous electron transfer rate and decreased overpotential by 0.4 V compared to stepwise pathways.

Conclusions:

• The Fe-S complex demonstrates catalytic activity for H2 evolution.
• Proton-coupled electron transfer (PCET) pathway offers significant kinetic and thermodynamic advantages.
• This work establishes an efficient catalytic system for proton reduction.