Forming Ferrocenyl Self‐Assembled Monolayers on Si(100) Electrodes with Different Alkyl Chain Lengths for Electron Transfer Studies

Abstract

The reaction of hydrogen‐terminated Si(100) with 1,8‐nonadiyne was previously shown to afford robust surfaces where oxidation of the substrate is not evident. Here, the experimental conditions required for reacting hydrogen‐terminated Si(100) with α,ω‐diynes of different lengths is explored via thermal hydrosilylation of 1,6‐heptadiyne, 1,8‐nonadiyne, 1,10‐undecadiyne and 1,15‐hexadecadiyne. X‐ray photoelectron spectroscopy indicated monolayers were successfully formed with oxide levels below the XPS detection limit for molecules with lengths varying from 7 to 11 carbons. It was observed that the apparent rate of electron transfer (ket) was affected not only by the SAM thickness, but also by hopping between ferrocene moieties where the presence of tiny oxidative defects act as electron transfer hotspots.

Surface Patterning of Biomolecules Using Click Chemistry and Light‐Activated Electrochemistry to Locally Generate Cu(I)

“…Chemical stability against oxidation was ensured by protecting the silicon (a‐Si) with a monolayer of 1,8‐nonadiyne, following a previously reported procedure [32] . The a‐Si were rinsed with dichloromethane followed by piranha cleaning (use with caution) for 30 min and then HF etching (2.5 %, use with caution) for 90 s. Hydrogen‐terminated samples were then transferred under an argon atmosphere to a flame‐dried Schlenk flask containing a small sample (1 mL) of degassed 1,8‐nonadiyne.…”

Light-Addressable Electrochemical Sensing of Dopamine Using on N-Silicon/gold Schottky Junctions

“…The vast majority of recent LAES studies to date use a Si electrode modified with a monolayer of 1,8-nonadiyne that protects the Si interface and provides a route for functionalizing the electrode with redox couples [10][11][12][33][34][35][36][37] or NPs. 32,38 This Si modification scheme has excellent electrochemical performance, stability, and versatility.…”

Reconsidering X-ray Photoelectron Spectroscopy Quantification of Substitution Levels of Monolayers on Unoxidized Silicon Surfaces

“…Here in our revised formulae, the thickness of the alkyl layer no longer needs to be calculated because the product of thickness and density is found in all the equations, which is equal to φ × nSi × Nchain, as per Eq.10; the substitution levels will be calculated directly from the revised formulae (vide infra). Within the continuum model as shown in Figure 5, the total Si 2p signal intensity at the alkyl chain-modified surface is given by 14If we assume , and , Eq 14 can be written as (15) Substituting Eq 10, , Eq 15 becomes (16) The carbon signal from the alkyl group is given by (17) where the same assumptions and substitutions are made when deriving Eq 16. The signal from the fluorine layer is given by (18) We can assume that , Eq 18 becomes Given that , the signal from the fluorine layer is given by (19) The intensity of adventitious carbon signal is given by (20) Combining Eq 17 and 20, the total intensity of the carbon signal is given by (21) After obtaining the intensity of the silicon signal, ISi (Eq 16), the intensity of fluorine signal, IF (Eq 19), and the total intensity of carbon signal, IC total (Eq 21), two quantification methods for the substitution level, using the ratio of C to Si, IC total /ISi, or the ratio of F to Si, IF/ISi, respectively, will be derived as shown below.…”