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Systematic Study on Morphological, Electrochemical Impedance, and Electrocatalytic Activity of Graphitic Carbon Nitride Modified on a Glassy Carbon Substrate from Sequential Exfoliation in Water
journal contribution
posted on 2021-08-25, 21:03 authored by Veeramani
Mangala Gowri, Ajay Ajith, S. Abraham JohnSeveral
researchers have synthesized graphitic carbon nitride (GCN)
from various precursors and attached it to electrode substrates after
exfoliation under different conditions and have reported inconsistent
data on electrochemical impedance, electroactive surface areas, and
electrocatalytic activity. Thus, the present study aims to study the
same systematically in addition to morphology after modifying GCN
on the GC substrate from different exfoliation times in water assisted
by sonication. The GCN was prepared from urea by bulk condensation
pyrolysis and then attached to the GC substrate by drop casting to
study its morphology, electrochemical impedance, and electrocatalytic
activity with respect to exfoliation. The SEM image of a GCN-modified
GC plate after 15 and 30 min of exfoliation shows bulky structure
whereas thin sheets of GCN were noticed after 120 min of exfoliation.
On the other hand, broken sheets were observed when GCN was coated
from beyond 120 min of exfoliation. The electrochemical impedance
studies show that the charge transfer resistance (RCT) of GCN modified from 15 and 30 min of exfoliation
was higher than that for the bare GC electrode. However, it started
to decrease while increasing the exfoliation time, and 1.8 kΩ
was obtained after 120 min of exfoliation. The RCT value was again increased to 3.2 and 5.0 kΩ for GCN
coated after 150 and 180 min of exfoliation, respectively. The electroactive
surface area (EASA) of GCN modified by 15 and 30 min of exfoliation
was less than that of the bare GC electrode, whereas it was 3.8-fold
higher for GCN coated from 120 min of exfoliation. The electrocatalytic
activity of the GC electrodes modified with GCN was then tested by
studying ascorbic acid (AA) and dopamine (DA) oxidation and reduction
of hydrogen peroxide (HP). Among the different exfoliation times,
GCN modified from 120 min of exfoliation displayed the highest electrocatalytic
activity toward AA, DA, and HP. This was attributed to its higher
EASA and lower charge-transfer resistance.
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Glassy Carbon Substrateexfoliation timeselectroactive surface areasGCN-modified GC plategraphitic carbon nitride120 minHPR CT valueGC electrodeEASASEM5.0 k ΩGC substrateelectrochemical impedance studies showDA30 minAAelectrocatalytic activityelectroactive surface area1.8 k Ωbulk condensation pyrolysiselectrochemical impedanceGraphitic Carbon Nitride Modifiedcharge transfer resistance