Abstract
Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.
Highlights
Nanostructured materials presenting dense arrays of electroactive domains have received growing attention in a number of applications during the last few years.[1,2,3] In particular, the increase of nanometric contacts over large effective areas in hybrid materials can improve their performance.[4]
The electrodes were immersed in a chloroform solution of C12-TAA molecules which were self-assembled in situ by visible light irradiation for one hour with a halogen lamp (10 W cm−2), and with the aim to non-covalently confine the resulting nanowires within the hydrophobic mesopores (Fig. 2d)
To first probe the presence of organic TAA molecules in the mesopores, X-ray photoelectron spectrometry (XPS) experiments were conducted on a series of electrodes after each modification (Table S1 in the Electronic supplementary information (ESI)†)
Summary
Nanostructured materials presenting dense arrays of electroactive domains have received growing attention in a number of applications during the last few years.[1,2,3] In particular, the increase of nanometric contacts over large effective areas in hybrid materials can improve their performance.[4]. Functional electrodes were first constructed on a gold surface by electrodeposition of silica using a mixture of tetraethylsiloxane (TEOS) in the presence of a surfactant (Fig. 2a and b).
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