Rational design of catalysts requires mechanistic understanding beyond overall performance measurements and benchmarking. By time-resolved laser spectroscopy reaction intermediates can be identified and their rates of interconversion can be determined. The combination of ultra-fast UV-VIS and mid-IR spectroscopy is useful also to follow reaction steps of molecular dyes and catalysts immobilized on mesoporous semi-conductor surfaces. We have been able to follow light-induced hole injection into NiO and subsequent, ultrafast electron transfer from dye to a biomimetic [FeFe] catalyst on a NiO surface. However, with other dyes the same catalyst reacted already with the excited dye, and rapid charge recombination followed. This shows the need for detailed investigations to understand and optimize dye-sensitized solar fuel devices. We have also been able to study several steps in the photoreduction cycle of CO2-reducing catalysts anchored onto TiO2. This has revealed an unexpected role of TiO2, as well as details of the TEOA donor reactions, in the photocatalytic CO2 reduction.

Capturing intermediates of molecular catalyst/semiconductor systems by transient mid-IR spectroscopy.

255th National Meeting (2018)

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