Nanoconfined self-assembly on a grafted graphitic surface under electrochemical control

Abstract

Highly oriented pyrolytic graphite (HOPG) can be covalently grafted with aryl radicals generated via the electrochemical reduction of 3,5-bis-tert-butyl-diazonium cations (3,5-TBD). The structure of the grafted layer and its stability under electrochemical conditions were assessed with electrochemical scanning tunneling microscopy (EC-STM) and cyclic voltammetry (CV). Stable within a wide (>2.5 V) electrochemical window, the grafted species can be locally removed using EC-STM-tip nanolithography. Using dibenzyl viologen as an example, we show that the generated nanocorrals of bare graphitic surface can be used to study nucleation and growth of self-assembled structures under conditions of nanoconfinement and electrochemical potential control.

Graphite and Graphene Fairy Circles: A Bottom-Up Approach for the Formation of Nanocorrals

“…The choice for NBD and TBD was motivated by their well-characterized functionalization of graphite and graphene. 24,29,36 The NBD and TBD solutions, or their mixtures, were immediately transferred to an electrochemical cell to perform grafting. Based on the previously established cyclic voltammetry (CV) protocol, 24 the substrate potential was swept three times (scan rate: 50 mV/s) from +0.5 V to -0.4 V (vs. Ag/AgCl) and back.…”

“…nm, leaving behind pristine graphite or graphene. 29,36,37 While this lithography approach gives rise to a very good control of the shape, size and orientation of the pristine graphene or graphite islands, the nature of the approach limits upscaling possibilities.…”

Reactivity on and of Graphene Layers: Scanning Probe Microscopy Reveals

“…15 a CV and STM of self-assembled porphyrin functionalized with electrochemically-active ferrocene moieties [80]. EC-STM operational scheme (b, [81]) and application for in situ generation of reduced viologens (c, [81]) and probing the catalytic activity of porphyrins on graphene (d, [82] (Fig. 16c, [84]); (d) lithographic patterning of a supramolecular host-guest multilayer (Fig.…”

“…And finally, such corrals can be used as nanoreactors with controlled shape, size and chemical functionality. For example, we have already demonstrated the use of such corrals for self-assembly of in situ generated EC-active species under full electrochemical control [81], and for the investigation of tip-induced and photochemical polymerization of diacetylenes under nanoconfinement ( Fig. 23f, h, [119]).…”

Unidirectional supramolecular self-assembly inside nanocorrals via in situ STM nanoshaving

“…in the presence of molecular building blocks, has emerged as a most powerful tool to create and characterize confined 2D assemblies. [23][24][25][26][27][28] In this approach a sacrificial blocking layer is locally shaved off by the probe, and molecules suspended in solution can adsorb and assemble on the exposed surface area. Previous in situ STM nanoshaving studies on graphite, both by our group and other groups, have shown a preferential molecular adsorption orientation inside the exposed surface area.…”