Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)

This work reports the fabrication of redox-active films of oligomeric and molecular viologens and mesoporous silica via the infiltration method. Pore-ellipsometry and UV-vis confirm that low-molecular-weight poly(viologens) in solution are able to enter the mesoporous structure, in contrast to high-...

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Publicado: 2019
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_14639076_v21_n5_p2743_SaintAndre
http://hdl.handle.net/20.500.12110/paper_14639076_v21_n5_p2743_SaintAndre
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_14639076_v21_n5_p2743_SaintAndre
record_format dspace
spelling paper:paper_14639076_v21_n5_p2743_SaintAndre2023-06-08T16:16:34Z Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens) This work reports the fabrication of redox-active films of oligomeric and molecular viologens and mesoporous silica via the infiltration method. Pore-ellipsometry and UV-vis confirm that low-molecular-weight poly(viologens) in solution are able to enter the mesoporous structure, in contrast to high-molecular weight polymers that adsorb only on top of the film. Cyclic voltammetry shows that viologens are able to reach the bottom of the pores and access the electrode/film interface. However, the number of viologen sites that can be accessed by cyclic voltammetry at 50 mV s-1 is only a tenth of the total viologen population determined by UV-vis and pore-ellipsometry. The effect is ascribed to the very small apparent diffusion coefficient for charge transport within the film (Dapp < 10-12 cm2 s-1). A theoretical model is put forward to describe charge transport via the electron-hopping mechanism for redox sites randomly adsorbed on the inner walls of the pores. Our model predicts that the threshold of charge percolation occurs for viologen surface coverages close to those observed in our experiments; therefore, the low fraction of electrochemically addressable viologens is ascribed to inefficient charge percolation via the electron-hopping mechanism. © 2019 the Owner Societies. 2019 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_14639076_v21_n5_p2743_SaintAndre http://hdl.handle.net/20.500.12110/paper_14639076_v21_n5_p2743_SaintAndre
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description This work reports the fabrication of redox-active films of oligomeric and molecular viologens and mesoporous silica via the infiltration method. Pore-ellipsometry and UV-vis confirm that low-molecular-weight poly(viologens) in solution are able to enter the mesoporous structure, in contrast to high-molecular weight polymers that adsorb only on top of the film. Cyclic voltammetry shows that viologens are able to reach the bottom of the pores and access the electrode/film interface. However, the number of viologen sites that can be accessed by cyclic voltammetry at 50 mV s-1 is only a tenth of the total viologen population determined by UV-vis and pore-ellipsometry. The effect is ascribed to the very small apparent diffusion coefficient for charge transport within the film (Dapp < 10-12 cm2 s-1). A theoretical model is put forward to describe charge transport via the electron-hopping mechanism for redox sites randomly adsorbed on the inner walls of the pores. Our model predicts that the threshold of charge percolation occurs for viologen surface coverages close to those observed in our experiments; therefore, the low fraction of electrochemically addressable viologens is ascribed to inefficient charge percolation via the electron-hopping mechanism. © 2019 the Owner Societies.
title Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
spellingShingle Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
title_short Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
title_full Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
title_fullStr Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
title_full_unstemmed Charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
title_sort charge percolation in redox-active thin membrane hybrids of mesoporous silica and poly(viologens)
publishDate 2019
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_14639076_v21_n5_p2743_SaintAndre
http://hdl.handle.net/20.500.12110/paper_14639076_v21_n5_p2743_SaintAndre
_version_ 1768542904124440576

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