| Autor: |
Gurrentz JM; The University of Texas at Austin, Austin, Texas 78757, United States., Rose MJ; The University of Texas at Austin, Austin, Texas 78757, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2020 Mar 25; Vol. 142 (12), pp. 5657-5667. Date of Electronic Publication: 2020 Mar 12. |
| DOI: |
10.1021/jacs.9b12824 |
| Abstrakt: |
We report here the remarkable and non-catalytic beneficial effects of a Ni(II) ion binding to a Si|PNP type surface as a result of significant thermodynamic band bending induced by ligand attachment and Ni(II) binding. We unambiguously deconvolute the thermodynamic flat band potentials ( V FB ) from the kinetic onset potentials ( V on ) by synthesizing a specialized bis-PNP macrochelate that enables one-step Ni(II) binding to a p-Si(111) substrate. XPS analysis and rigorous control experiments confirm covalent attachment of the designed ligand and its resulting Ni(II) complex. Illuminated J - V measurements under catalytic conditions show that the Si|BisPNP-Ni substrate exhibits the most positive onset potential for the hydrogen evolution reaction (HER) (-0.55 V vs Fc/Fc + ) compared to other substrates herein. Thermodynamic flat band potential measurements in the dark reveal that Si|BisPNP-Ni also exhibits the most positive V FB value (-0.02 V vs Fc/Fc + ) by a wide margin. Electrochemical impedance spectroscopy data generated under illuminated , catalytic conditions demonstrate a surprising lack of correlation evident between V on and equivalent circuit element parameters commonly associated with HER. Overall, the resulting paradigm comprises a system wherein the extent of band bending induced by metal ion binding is the primary driver of photoelectrochemical (PEC)-HER benefits, while the kinetic (catalytic) effects of the PNP-Ni(II) are minimal. This suggests that dipole and band-edge engineering must be a primary design consideration (not secondary to catalyst) in semiconductor|catalyst hybrids for PEC-HER. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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