Molecular approaches to solar-energy conversion require a kinetic optimization of light-induced electron-transfer reactions. At molecular–semiconductor interfaces, this optimization has previously been accomplished through control of the distance between the semiconductor donor and the molecular acceptor and/or the free energy that accompanies electron transfer. Here we show that a kinetic pathway for electron transfer from a semiconductor to a molecular acceptor also exists and provides an alternative method for the control of interfacial kinetics. The pathway was identified by the rational design of molecules in which the distance and the driving force were held near parity and only the geometric torsion about a xylyl- or phenylthiophene bridge was varied. Electronic coupling through the phenyl bridge was a factor of ten greater than that through the xylyl bridge. Comparative studies revealed a significant bridge dependence for electron transfer that could not be rationalized by a change in distance or driving force. Instead, the data indicate an interfacial electron-transfer pathway that utilizes the aromatic bridge orbitals.
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Photogenerated hole traps in metal-organic-framework photocatalysts for visible-light-driven hydrogen evolution
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Nature Communications Open Access 30 August 2017
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The University of North Carolina (UNC) authors gratefully acknowledge support by a grant from the Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy Research, US Department of Energy (DE-SC0013461). The University of British Columbia authors are grateful to the Canadian Natural Science and Engineering Research Council, Canadian Foundation for Innovation, Canadian Institute for Advanced Research and Canada Research Chairs for support. The authors thank M. Gish and the Papanikolas group at UNC for the ultrafast measurements.
The authors declare no competing financial interests.
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Hu, K., Blair, A., Piechota, E. et al. Kinetic pathway for interfacial electron transfer from a semiconductor to a molecule. Nature Chem 8, 853–859 (2016). https://doi.org/10.1038/nchem.2549
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