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Developments of scanning gel electrochemical microscopy

Abstract : In the past 30 years, scanning electrochemical probe microscopy (SEPM) techniques have been developed as powerful tools for studying electrochemistry at micro/nano scale. The most developed and commercialized techniques are Scanning Electrochemical Microscopy (SECM) and Scanning Ion Conductance Microscopy (SICM). However, the entire sample is immersed in the electrolyte solution during the measurements, which may yield uncontrolled change of the surface due to the long scanning time. Instead of localizing electrode, the electrolyte can also be localized, which is known as Scanning Droplet Cell (SDC) or Scanning Electrochemical Cell Microscopy (SECCM). The experiments are carried out under ambient conditions. However, the spreading of droplet over sample surface may be affected by the hydrophilicity and roughness of sample, which brings challenges in quantitative analysis. Recently, Scanning Gel Electrochemical Microscopy (SGECM) was reported by our group as a novel SEPM technique. It is mainly based on a gel probe that immobilizes the electrolyte on a micro-disk electrode. Thus, the analysis can be achieved in ambient environment with controllable electrolyte spreading. This thesis is devoted to the further developments of SGECM. Foremost, the background of developments of SGECM is introduced in Chapter I. Different SEPM techniques, gel polymer electrolytes, achievements of SGECM are systematically presented, respectively. In Chapter II, the lateral physical resolution of SGECM is thoroughly and quantitatively studied by both marking single pixels and scanning over periodic samples. In chapter III, the potentiometric mode of SGECM is developed based on a novel Ag/AgCl-gel micro-reference electrode. As the gel probe undergoes thousands of pressing-stretching cycles in a mapping measurement, it is highly important to improve its mechanical strength. Chapter IV describes the preliminary effort of chemically cross-linking chitosan gel by glutaraldehyde. Chapter V further pushes forward the development of integrated gel probes with both working and reference electrode.
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Submitted on : Monday, June 28, 2021 - 11:27:20 AM
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  • HAL Id : tel-03272273, version 1

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Ning Dang. Developments of scanning gel electrochemical microscopy. Analytical chemistry. Université de Lorraine, 2020. English. ⟨NNT : 2020LORR0243⟩. ⟨tel-03272273⟩

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