Electrochemical grafting of heterocyclic molecules on glassy carbon and platinum using heteroaromatic iodonium salts or iodo-substituted heteroaromatics

Sommerfeldt, Andreas; Pedersen, Steen Uttrup; Daasbjerg, Kim

doi:10.1016/j.electacta.2017.12.052

Cited by 6 publications

(4 citation statements)

References 31 publications

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“…In 1983, Amatore et al described that the dimensionless current in CV and the apparent rate constant are mostly related to θ, which is the insulator coverage. Following Amatore’s model and our further work, a technique from CV to identify the grafting layer has already been applied in many articles. ,− Specifically, the dimensionless current in CV and the apparent rate constant mostly rely on θ. Then, the dimensionless current can be described by following equations on a covered electrode. normalΨ normalm normalo normald normali normalf normali normale normald = normalΨ normalb normala normalr normale · ( 1 − θ ) where normalΨ normalb normala normalr normale = normalΛ · exp ( α · ε ) · [ 1 − Ι Ψ · false[ 1 + exp ( − ε ) false] ] where Ψ bare and Ψ modified are the dimensionless current at a bare electrode and the modified electrode in the CV; ΙΨ is the convolution integral of the resolution of the Fick equation .…”

Section: Resultsmentioning

confidence: 99%

Visualizing Water Reduction with Diazonium Grafting on a Glassy Carbon Electrode Surface in a Water-in-Salt Electrolyte

Zhu

Droguet

Deng

et al. 2023

ACS Appl. Mater. Interfaces

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Aqueous batteries are regaining interest, thanks to the extended working stability voltage window in a highly concentrated electrolyte, namely the water-in-salt electrolyte. A solid-electrolyte interphase (SEI) forms on the negative electrode to prevent water access to the electrode surface. However, we further reported that the formed SEI layer was not uniform on the surface of the glassy carbon electrode. The SEI after passivation will also show degradation during the remaining time of opencircuit voltage (OCV); hence, it calls for a more stable passivation layer to cover the electrode surface. Here, a surface modification was successfully achieved via artificial diazonium grafting using monomers, such as poly(ethylene glycol), α-methoxy, ω-allyloxy (PEG), and allyl glycidyl cyclocarbonate (AGC), on glassy carbon. Physical and electrochemical measurements indicated that the hydrophobic layer composed of PEG or AGC species was well grafted on the electrode surface. The grafted hydrophobic coatings could protect the electrode surface from the water molecules in the bulk electrolyte and then suppress the free water decomposition (from LSV) but still migrating lithium ions. Furthermore, multiple cycles of CV with one-hour resting OCV identified the good stability of the hydrophobic grafting layer, which is a highlight compared with our precious work. These findings relying on the diazonium grafting design may offer a new strategy to construct a stable artificial SEI layer that can well protect the electrode surface from the free water molecule.

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Section: Resultsmentioning

confidence: 99%

Visualizing Water Reduction with Diazonium Grafting on a Glassy Carbon Electrode Surface in a Water-in-Salt Electrolyte

Zhu

Droguet

Deng

et al. 2023

ACS Appl. Mater. Interfaces

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“…This is also reflected in the differences observed in the thickness of the films wherein the Ar-D films exhibit a higher thickness that increases at a faster rate as a function of concentration, at least at lower concentrations. On the other hand, iodonium salts do not decompose spontaneously either in solution 37 or assisted by the carbon substrate (Scheme 2d,e). 34 This means that the electroreduction of the salt and the subsequent generation of the aryl radicals only occur in the close vicinity of the electrode surface, enabling a higher degree of direct covalent attachment to the substrate (Scheme 2f).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Among these, iodonium salts have emerged as promising alternatives to the quintessential diazonium salts. Their higher stability ensures no spontaneous reaction in solution as well as in the presence of the substrate, a trait highly desired for patterning purposes. , More importantly, the higher stability and the structural diversity of iodonium salts allow grafting of a wide variety of organic moieties, including heterocycles and alkynyl groups. ,, …”

Section: Introductionmentioning

confidence: 99%

“…Their higher stability ensures no spontaneous reaction in solution 37 as well as in the presence of the substrate, 38 a trait highly desired for patterning purposes. 39,40 More importantly, the higher stability and the structural diversity of iodonium salts allow grafting of a wide variety of organic moieties, including heterocycles 37 and alkynyl groups. 34,41,42 Iodonium salts undergo a one-electron reduction reaction similar to aryldiazonium salts.…”

Section: ■ Introductionmentioning

confidence: 99%

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Covalent Functionalization of Carbon Surfaces: Diaryliodonium versus Aryldiazonium Chemistry

et al. 2020

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Covalently modified carbon surfaces remain central to a number of applications. Surface modification is often achieved using aryldiazonium chemistry, which has become the gold standard for the functionalization of carbon-based surfaces. However, the higher reactivity and thus the lower stability of diazonium precursors at carbon interfaces have prompted a search for alternative chemistries. Diaryliodonium salts have emerged as stable alternatives to the conventional aryldiazonium precursors. In this contribution, we provide a detailed comparison between the two types of chemistries by carrying out electrochemical covalent grafting of graphite substrates using nitrophenyl groups generated from the corresponding aryldiazonium and diaryliodonium salts under identical experimental conditions. The electrochemical process was studied using cyclic voltammetry, whereas the covalently grafted substrates were characterized using a battery of surface analytical techniques spanning multiple length scales. Analysis of the modified substrates using Raman spectroscopy revealed that the efficiency of covalent grafting is higher for iodonium chemistry than that for aryldiazonium chemistry. This observation was further corroborated by detailed morphological characterization of the covalent films using atomic force microscopy and molecular-resolution scanning tunneling microscopy, which revealed higher surface coverage for iodonium modified substrates. The chemical composition of the films was probed using X-ray photoelectron spectroscopy. The detailed and systematic comparison presented here clearly demonstrates that diaryliodonium chemistry presents a robust and reliable alternative to the widely used aryldiazonium chemistry.

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Iodonium Salts as Reagents for Surface Modification: From Preparation to Reactivity in Surface-Assisted Transformations

Guselnikova

Soldatova

Postnikov

2022

Aryl Diazonium Salts and Related Compounds

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Electrochemical grafting of heterocyclic molecules on glassy carbon and platinum using heteroaromatic iodonium salts or iodo-substituted heteroaromatics

Cited by 6 publications

References 31 publications

Visualizing Water Reduction with Diazonium Grafting on a Glassy Carbon Electrode Surface in a Water-in-Salt Electrolyte

Visualizing Water Reduction with Diazonium Grafting on a Glassy Carbon Electrode Surface in a Water-in-Salt Electrolyte

Covalent Functionalization of Carbon Surfaces: Diaryliodonium versus Aryldiazonium Chemistry

Iodonium Salts as Reagents for Surface Modification: From Preparation to Reactivity in Surface-Assisted Transformations

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