pH sensitivity of interfacial electron transfer at a supported graphene monolayer

Wehrhold, Michel; Neubert, Tilmann J; Yadav, Anur; Vondráček, Martin; Iost, Rodrigo M.; Honolka, Jan; Balasubramanian, Kannan

doi:10.1039/c9nr05049c

Cited by 21 publications

(36 citation statements)

References 89 publications

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“…It is known in carbon research that the preparation of the electrode has a strong effect on the ensuing electrochemical characteristics. 17,24,25 This is in contrast to non-crystalline metal electrodes, where polycrystalline or amorphous planar electrodes give similar electrochemical behavior rather independent of the preparation strategy. This work underlines the necessity to perform sample preparation carefully in order to assess the maximum achievable performance.…”

Section: Discussionmentioning

confidence: 94%

“…Graphene monolayer electrodes were prepared according to a fabrication strategy that we have outlined in our previous works. 17 Specifically, we use polystyrene as a polymer support to coat Highly Durable Graphene under HER Cycling Wehrhold et al 4 commercially obtained graphene on copper foils. The copper is etched away in an acidified peroxide solution, followed by transfer of the polystyrene-graphene stack on to a Si/SiO2 substrate with pre-fabricated platinum contacts (see Methods in SI for details).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, we ensure that we have a high proportion of sp 2 -carbon, as confirmed by our previous XPS measurements. 17 In our case, this is achieved by the annealing procedure, which minimizes organic contamination. We have also extracted a measure of the exchange current density in our electrode (see figure S7b in SI), which lies in the range of 4-10 µA cm -2 .…”

Section: Resultsmentioning

confidence: 99%

“…In this work, we focus on single CVD-grown graphene sheets on an insulating SiO2 substrate and show that we can indeed realize graphene electrodes that show a high stability to HER for numerous cycles in three different acid solutions: HCl, HClO4 and H2SO4. Specifically, we use an optimized preparation strategy, 16,17 which involves metal-ion-free etching of the copper substrate followed by an annealing and electrochemical etching step 18 to prepare intact single layer graphene electrodes mostly free of trace metal impurities. A graphene sheet prepared in this manner is very stably held on the insulating SiO2 substrate.…”

Section: Introductionmentioning

confidence: 99%

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Highly Durable Graphene Monolayer Electrode on Insulating Substrate under Long-term Hydrogen Evolution Cycling

Wehrhold¹,

Neubert²,

Grosser³

et al. 2022

Preprint

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Electrochemical hydrogen evolution reaction (HER) at single graphene sheets has been investigated widely either in its pristine form or after chemical modification. One important challenge is the long-term stability of single graphene sheets on Si/SiO2 substrates under HER. Previous reports have found that due to stress developing under gas evolution, the sheets tend to break apart, with a very low lifetime limited to just a few cycles of HER. Here, we show through appropriate electrode preparation that it is possible to achieve highly durable single graphene electrodes on insulating substrates, which can survive several hundreds of HER cycles with virtually no damage to the sp2-carbon framework. Through systematic investigations including atomic force microscopy, Raman spectroscopy and electroanalysis, we show that even after so many cycles, the sheet is physically intact and the electron transfer capability of the electrodes remain unaffected. This extremely high stability of a single atomic sheet of carbon, when combined with appropriate chemical modification strategies, will pave way for the realization of novel 2D electrocatalysts.

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Section: Discussionmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Highly Durable Graphene Monolayer Electrode on Insulating Substrate under Long-term Hydrogen Evolution Cycling

Wehrhold¹,

Neubert²,

Grosser³

et al. 2022

Preprint

Self Cite

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“…Monolayer graphene electrodes on Si/SiO 2 substrates with pre‐patterned metal contacts were prepared as outlined in our earlier works [3a,d] . (see Figure S1 in supporting information (SI) and experimental section for details).…”

Section: Resultsmentioning

confidence: 99%

Graphene‐Mercury‐Graphene Sandwich Electrode for Electroanalysis

et al. 2021

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We present a new class of hybrid 2D electrodes, where mercury is incorporated between two graphene monolayers, prepared by bottom‐up assembly. First, the bottom graphene layer is electrochemically modified leading to the creation of fine mercury nanodroplets of variable size on the graphene surface. Although such electrodes show good sensitivity to heavy metal ions, their stability is limited due to the outgassing of mercury over time. After coverage with a top monolayer, the graphene surface is rendered with the favorable properties of mercury such as the high overpotential for hydrogen evolution, the ability to work at a broader cathodic potential range and higher sensitivity towards heavy metal ions such as Cd2+ and Pb2+. Most importantly, the outgassing of mercury is completely hindered by the top layer, which yields a stable mercury‐like electrode but with a carbonaceous non‐toxic interface. We attribute the favorable properties of the sandwich electrode to the subsurface mercury present below the top graphene sheet, which renders it with new electrochemical properties.

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Electrochemical Surface Plasmon Resonance Sensing using a van der Waals Heterostructure

Jungnickel,

Balasubramanian

2024

Advanced Sensor Research

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Coupling surface plasmon resonance (SPR) sensing with electrochemistry (EC) is a promising analytical strategy to obtain information about interfacial phenomena in heterogeneous reactions. Typical EC‐SPR sensors utilize a metal film both as the plasmonic material and as the working electrode. In this configuration, the eigenmodulation of the plasmonic properties of the metal film under applied potential results in a background signal, which hampers the unambiguous interpretation of the sensor response due to redox reactions. Here, a new strategy is presented to overcome this disadvantage by using a van der Waals heterostructure (vdW‐HS) as the working electrode. The vdW‐HS comprises of a graphene / hexagonal boron nitride (hBN) stack on a gold film of a standard SPR sensor. It is shown here that the background signal is completely suppressed enabling the unambiguous analysis of SPR sensor response due to electrochemical reactions. It is further observed that the potential dependent plasmonic signals are not just a reproduction of the electrochemical current and subtle differences can be traced back to the diffusive nature of the redox active species. Finally, it is demonstrated that EC‐SPR can be used as a complementary method to distinguish if the electrochemical response is mainly surface‐bound or due to diffusion.

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pH sensitivity of interfacial electron transfer at a supported graphene monolayer

Abstract: Electron transfer rates at graphene are found to vary with pH, attributed to electrostatic effects at the graphene-liquid interface.

Cited by 21 publications

References 89 publications

Highly Durable Graphene Monolayer Electrode on Insulating Substrate under Long-term Hydrogen Evolution Cycling

Highly Durable Graphene Monolayer Electrode on Insulating Substrate under Long-term Hydrogen Evolution Cycling

Graphene‐Mercury‐Graphene Sandwich Electrode for Electroanalysis

Electrochemical Surface Plasmon Resonance Sensing using a van der Waals Heterostructure

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