Perturbation Electrochemiluminescence Imaging to Observe the Fluctuation of Charge-Transfer Resistance in Individual Graphene Microsheets with Redox-Induced Defects

Abstract

Here, the fluctuation of charge-transfer resistance in individual reduced graphene oxide (rGO) microsheets with more redox-induced defects is unprecedentedly visualized using a perturbation electrochemiluminescence (ECL) imaging. This perturbation uses a short and low potential to recover defect-covered rGO microsheets slightly and then introduces a high potential to form more redox-induced defects resulting in an increase of charge-transfer resistance. Also, these defects at rGO microsheets enhance their catalytic feature and the resultant ECL intensity so that the temporal resolution in ECL imaging is improved to 30 ms. Aided by this fast imaging approach, the exponential decrease of ECL intensity at individual graphene microsheets after the oxidation is observed, which reflects the increase of their charge-transfer resistances. Since the charge-transfer resistance at electrode surfaces is mainly affected by the conductivity of electrode materials, the result provides the dynamic information to support the reduction of the electrical conductivity in graphene with more defects.

High Spatial Resolution Electrochemical Microscopic Observation of Enhanced Charging under Bias at Active Sites of N-rGO

“…With the nanodroplet as the electrochemical cell, the circuit is modeled as a Randles model (the inset of Figure A), where R s represents the solution resistance, R f represents the faradic resistance, and C dl represents the capacitance of the double layer. During the initial charging process, the non-faradic component is dominant in the total current, which comes from the charge accumulation at the electrode surface. − According to the classic electrochemical theory, the electrode charge is decided by the surface capacitance ( C dl ). In the follow-up charging process, the non-faradic component decreases, and the faradic component increases synchronously.…”

Electrogenerated Chemiluminescence and Electroluminescence of N‐Doped Graphene Quantum Dots Fabricated from an Electrochemical Exfoliation Process in Nitrogen‐Containing Electrolytes

“…[20] ECL has been widely used in many applicationsi ncluding immunoassays and analyte detection due to its high sensitivity and wide dynamic range. [21][22][23][24][25][26][27] ECL has also been reported in several light-emitting applications, where solid-state devices utilizing traditional ECL luminophores exhibited highly efficient, low-voltage operation. [28][29][30][31] The first example of ap olymer light-emitting electrochemical cell (LEC) was introduced in 1995.…”

“…Due to the high redox power of these radicals, ECL generated via the coreactant pathway is often enhanced compared to the annihilation route [20] . ECL has been widely used in many applications including immunoassays and analyte detection due to its high sensitivity and wide dynamic range [21–27] . ECL has also been reported in several light‐emitting applications, where solid‐state devices utilizing traditional ECL luminophores exhibited highly efficient, low‐voltage operation [28–31] …”

High-resolution imaging of catalytic activity of a single graphene sheet using electrochemiluminescence microscopy

“… 27 The computational result confirms that the ECL reaction will easily start once the ECL reactants are absorbed onto the surface of the catalyst. Since rGO can electrocatalyze the reaction between L012 and H 2 O 2 to emit ECL light, 36 it is reasonable to assume that L012 and hydrogen peroxide are adsorbed at the surface of rGO. Hydrogen peroxide is electrochemically oxidized into hydroperoxide intermediates by the catalysis of rGO.…”