The Critical Role Played by the Catalytic Moiety in the Early-Time Photodynamics of Hydrogen-Generating Bimetallic Photocatalysts

Qing Pan; Francesco Mecozzi; Jeroen P Korterik; Johannes G Vos; Wesley R Browne; Annemarie Huijser

doi:10.1002/cphc.201600458

The Critical Role Played by the Catalytic Moiety in the Early-Time Photodynamics of Hydrogen-Generating Bimetallic Photocatalysts

Chemphyschem. 2016 Sep 5;17(17):2654-9. doi: 10.1002/cphc.201600458. Epub 2016 Jul 5.

Authors

Qing Pan¹, Francesco Mecozzi², Jeroen P Korterik¹, Johannes G Vos³, Wesley R Browne², Annemarie Huijser⁴

Affiliations

¹ MESA+Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
² Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747 AG, Groningen, The Netherlands.
³ SRC for Solar Energy Conversion, School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
⁴ MESA+Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. j.m.huijser@utwente.nl.

PMID: 27258159
DOI: 10.1002/cphc.201600458

Abstract

The effect of the catalytic moiety on the early-time photodynamics of Ru/M (M=Pt or Pd) bimetallic photocatalysts is studied by ultrafast transient absorption spectroscopy. In comparison to the Ru/Pd photocatalyst described earlier, the Ru/Pt analogue shows complex excited-state dynamics with three distinct kinetic components ranging from sub-ps to 10(2) ps, requiring a more sophisticated photophysical model than that developed earlier for the Ru/Pd complex. In the Pu/Pt photocatalyst, an additional lower-lying excited state is proposed to quench the hot higher-lying triplet metal-to-ligand charge-transfer states. Furthermore, a strong excitation wavelength dependence on the population of excited states is observed for both the Ru/Pt and Ru/Pd complexes, indicating a non-equilibrated distribution even on the 10(2) ps timescale. These insights shed light on the significant impact of the catalytic moiety on the fundamental early-time photophysics of Ru-based photocatalysts.

Keywords: molecular photocatalysis; non-equilibrated excited states; photodynamics; ruthenium; transient absorption.