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Title: Electrochemical Characterization and Catalytic Application of Gold-Supported Ferrocene-Containing Diblock Copolymer Thin Films in Ethanol Solution

This study reports the electrochemical behavior and catalytic property of electrode-supported thin films of polystyrene- block-poly(2-(acryloyloxy)ethyl ferrocenecarboxylate) (PS- b-PAEFc) in an ethanol (EtOH) solution. The electrochemical properties of PS- b-PAEFc films with different PAEFc volume fractions (f PAEFc = 0.47, 0.30, and 0.17) in 0.1 M ethanolic sodium hexafluorophosphate were compared with those in an acetonitrile (MeCN) solution of 0.1 M tetrabutylammonium hexafluorophosphate. Pristine PS- b-PAEFc films did not afford significant faradaic currents in the EtOH solution because EtOH is a nonsolvent for both PS and PAEFc. However, the films could be rendered redox-active in the EtOH solution by applying potentials in the MeCN solution to induce the redox-associated incorporation of the supporting electrolytes into the films. Atomic force microscopy images verified the stability of PAEFc microdomains upon electrochemical measurements in these solutions. Cyclic voltammograms measured in the EtOH solution for PS- b-PAEFc with the larger f PAEFc were diffusion-controlled regardless of ellipsometric film thickness (23 – 152 nm) at relatively slow scan rates, in contrast to those in the MeCN solution that were controlled by surface-confined redox species. The electron propagation efficiency in the EtOH solution was significantly lower than that in the MeCN solution due to the poorermore » swelling of the films, which limited the migration of counter ions and the collisional motions of the ferrocene moieties. PS- b-PAEFc films were applied as electrochemically-responsive heterogeneous catalysts based on the ferrocenium moieties for Michael addition reaction between methyl vinyl ketone and ethyl 2-oxocyclopentanecarboxylate (E2OC) in 0.1 M NaPF 6/EtOH. The catalytic activities of thin films were similar regardless of f PAEFc, suggesting that the catalytic reaction took place for the reactants that could penetrate through the film and reach PAEFc microdomains communicable with the underlying electrode. Interestingly, the permeability of PS-b-PAEFc films provided a means to control the reaction selectivity, as suggested by negligible reaction of E2OC with trans-4-phenyl-3-buten-2-one.« less
Authors:
; ; ; ORCiD logo
Publication Date:
Grant/Contract Number:
SC0002362
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 3; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
Kansas State Univ., Manhattan, KS (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Department of Chemistry, Kansas State University Department of Chemistry, Indiana University
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ferrocene-containing block copolymer; electron hopping; solvent swelling; electrochemically-responsive heterogeneous catalysis; permeability-based selectivity
OSTI Identifier:
1337389