Electrochemical gating of single osmium molecules tethered to Au surfaces.
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| Title: | Electrochemical gating of single osmium molecules tethered to Au surfaces. |
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| Authors: | Herrera, Santiago1, Adam, Catherine1, Ricci, Alejandra, Calvo, Ernesto1 calvo@qi.fcen.uba.ar |
| Source: | Journal of Solid State Electrochemistry. Apr2016, Vol. 20 Issue 4, p957-967. 11p. |
| Subjects: | Osmium, Gold, Electrochemical analysis, Electron transport, Electrodes |
| Abstract: | The electrochemical study of electron transport between Au electrodes and the redox molecule Os[(bpy)(PyCH NHCO-]ClO tethered to molecular linkers of different length (1.3 to 2.9 nm) to Au surfaces has shown an exponential decay of the rate constant k with a slope β = 0.53 consistent with through bond tunneling to the redox center. Electrochemical gating of single osmium molecules in an asymmetric tunneling nano-gap between a Au(111) substrate electrode modified with the redox molecules and a Pt-Ir tip of a scanning tunneling microscope was achieved by independent control of the reference electrode potential in the electrolyte, E − E, and the tip-substrate bias potential, E. Enhanced tunneling current at the osmium complex redox potential was observed as compared to the off resonance set point tunneling current with a linear dependence of the overpotential at maximum current vs. the E. This corresponds to a sequential two-step electron transfer with partial vibration relaxation from the substrate Au(111) to the redox molecule in the nano-gap and from this redox state to the Pt-Ir tip according to the model of Kuznetsov and Ulstrup (J Phys Chem A 104: 11531, 2000). Comparison of short and long linkers of the osmium complex has shown the same two-step ET (electron transfer) behavior due to the long time scale in the complete reduction-oxidation cycle in the electrochemical tunneling spectroscopy (EC-STS) experiment as compared to the time constants for electron transfer for all linker distances, k. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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