Ultrafast Electron Transfer from CdSe Quantum Dots to a [FeFe]-Hydrogenase Mimic

The combination of CdSe nanoparticles as photosensitizers and [FeFe]-hydrogenase mimics is known to result in efficient systems for light-driven hydrogen generation. Nevertheless, little is known about the details of the light-induced charge-transfer processes. Here we investigate the timescale of light-induced electron transfer between CdSe quantum dots and a simple [FeFe]-hydrogenase mimic adsorbed on the surface of the quantum dot under non-catalytic conditions. Our time-resolved spectroscopic investigation shows that hot electron transfer on a sub-ps timescale and band-edge electron transfer on a sub-10-ps timescale occurs. Fast recombination is observed in the absence of a sacrificial agent or protons, which under real catalytic conditions would quench remaining holes or could stabilize the charge separation.