Photosensitized Hydrogen Evolution on a Floating Electrocatalyst Coupled to Electrochemical Recycling

Photoexcited protonated tetrathiafulvalene (HTTF⁺) was found to act as a photosensitizer, injecting electrons into Pt microparticles (floating electrocatalysts) to produce H₂ and TTF^•+ in acidic acetonitrile. In addition, TTF^•+ was electrochemically reduced back to TTF on a carbon electrode, to be further protonated to continuously produce H₂ photochemically. The onset potential for the electrochemical recycling of TTF^•+ on carbon was set at a potential 500 mV more positive than the potential required for the direct reduction of protons. HTTF⁺ showed no signs of decomposition after 51 h of continuous recycling and photoinduced production of H₂, proving stability and reversibility.