Limiting Molecular Twisting: Upgrading a Donor-Acceptor Dye to Drive H₂ Evolution.

Area of Science:

• Materials Science
• Photochemistry
• Electrochemistry

Background:

• Donor-acceptor (D-A) dyes like P1 are used to functionalize NiO photocathodes for proton reduction.
• Photoinduced intramolecular twisting of D-A dyes can affect their energy levels and performance.
• Controlling dye conformation is crucial for optimizing photoelectrochemical devices.

Purpose of the Study:

• To investigate the effect of co-adsorbed myristic acid (MA) on the photoinduced twisting of P1 dye on NiO.
• To understand how MA influences charge separation, recombination, and electrochemical potential.
• To explore the potential for MA-induced hydrogen evolution without a dedicated catalyst.

Main Methods:

• Co-adsorption of P1 dye and myristic acid (MA) on NiO photocathodes.
• Density Functional Theory (DFT) calculations.
• Time-resolved photoluminescence spectroscopy.

Main Results:

• MA suppresses photoinduced twisting of the P1 dye on NiO.
• Suppressed twisting retards charge recombination and increases photocurrent.
• MA co-adsorption enables direct H2 evolution, attributed to Ni nanoparticle formation and catalysis.

Conclusions:

• Controlling intramolecular twisting of D-A dyes is vital for efficient solar fuel devices.
• Designing twisting-limited D-A dyes offers a promising strategy for enhanced photoelectrochemical performance.
• MA's role in tuning dye behavior and enabling catalyst-free H2 evolution is demonstrated.