Activating a [FeFe] Hydrogenase Mimic for Hydrogen Evolution under Visible Light

Area of Science:

• Bioinorganic Chemistry
• Photocatalysis
• Materials Science

Background:

• Natural [FeFe] hydrogenases are highly efficient catalysts for hydrogen production.
• Precious metal-free catalysts are desirable for sustainable energy applications.
• Developing artificial systems that mimic natural enzymes is a key research area.

Purpose of the Study:

• To design and synthesize a compact, precious metal-free photosensitizer-catalyst dyad (PS-CAT).
• To investigate the photocatalytic hydrogen evolution activity of the PS-CAT under visible light.
• To elucidate the mechanism of action using spectroscopic and electrochemical methods.

Main Methods:

• Synthesis of a π-conjugated oligothiophene-based photosensitizer-catalyst dyad.
• Steady-state and time-resolved spectroscopy.
• Electrochemical techniques and photocatalytic experiments.
• Operando Electron Paramagnetic Resonance (EPR) spectroscopy.
• Theoretical calculations.

Main Results:

• The PS-CAT effectively drove photocatalytic hydrogen evolution under visible light.
• Operando EPR spectroscopy identified an active [Fe^I Fe⁰ ] species.
• Theoretical calculations supported the proposed active species.
• A turnover number (TON) of approximately 210 was achieved.

Conclusions:

• The designed precious metal-free PS-CAT is a promising system for visible light-driven hydrogen evolution.
• The active [Fe^I Fe⁰ ] species plays a crucial role in the catalytic process.
• This work provides a blueprint for developing artificial hydrogenase mimics.