Ultrafast Electron Transfer Between Dye and Catalyst on a Mesoporous NiO Surface

Area of Science:

• Materials Science
• Photochemistry
• Renewable Energy

Background:

• Dye-sensitized solar fuel devices (DSSFDs) require efficient charge transfer between semiconductors, dyes, and catalysts.
• Controlling interfacial and surface charge dynamics is crucial for optimizing DSSFD performance.

Purpose of the Study:

• To investigate light-induced electron transfer processes in p-type NiO films co-sensitized with coumarin C343 and a [FeFe]-proton reduction catalyst.
• To evaluate the efficiency and timescale of interfacial and surface charge transfer for potential DSSFD applications.

Main Methods:

• Utilized transient optical spectroscopy to probe ultrafast electron transfer dynamics.
• Employed p-type NiO films co-sensitized with coumarin C343 dye and a bioinspired [FeFe](mcbdt)(CO)6 proton reduction catalyst.

Main Results:

• Observed ultrafast interfacial electron transfer (hole injection) from NiO to excited coumarin C343 dye (τ ≈ 200 fs).
• Demonstrated rapid and efficient surface electron transfer from the reduced dye (C343-) to the coadsorbed [FeFe] catalyst (t1/2 ≈ 10 ps).
• Detected a persistent spectroscopic signature of the reduced catalyst lasting tens of microseconds before charge recombination.

Conclusions:

• The study confirms rapid surface electron transfer from dye to catalyst on NiO films.
• The relatively long lifetime of the charge-separated state indicates potential for these systems in DSSFD photocathodes.
• Highlights the promise of bioinspired catalysts and molecular dyes for efficient solar fuel generation.