Bio-inspired Catalyst-Modified Photocathode for Bias-Free Photoelectrochemical NADH Regeneration

Area of Science:

• * Electrochemistry
• * Catalysis
• * Renewable Energy

Background:

• * Nicotinamide adenine dinucleotide (NADH) is vital for enzymatic synthesis but costly to supply stoichiometrically.
• * Natural cofactor regeneration in photosystem I (PSI) offers a model for efficient artificial systems.

Purpose of the Study:

• * To develop a cost-effective and efficient method for NADH regeneration using photoelectrochemical catalysis.
• * To mimic photosystem I (PSI) for artificial cofactor regeneration.
• * To integrate NADH regeneration into a bias-free catalytic system for chemical synthesis.

Main Methods:

• * Construction of catalyst-modified polythiophene-based semiconductor (PTTH) photocathodes.
• * Self-assembly of [Rh(Cp * )(bpy)] catalyst with viologen (vi 2+) mediators on PTTH.
• * Fabrication of a tandem photoelectrochemical cell with a CoPi@BiVO 4 photoanode and Rh-vi 2+@PTTH photocathode.
• * Direct application of photo-generated NADH in glutamate dehydrogenase (GDH) catalyzed reactions.

Main Results:

• * The Rh-vi 2+@PTTH photocathode achieved high photocurrent density (-665 µA cm -2) and turnover frequency (TOF, 168.4 h -1).
• * The tandem cell operated without external bias, yielding a production rate of 42.5 µm h -1 cm -2 and TOF of 179.3 h -1.
• * Successfully demonstrated NADH-assisted catalytic conversion of α-ketoglutarate to L-glutamate.

Conclusions:

• * Developed a novel, bias-free photoelectrochemical system for efficient NADH regeneration.
• * Mimicking natural photosystem processes provides a viable strategy for artificial cofactor regeneration.
• * The system holds promise for sustainable chemical synthesis and biocatalysis.