posted on 2020-03-31, 13:11authored byVijay
S. Sapner, Parag P. Chavan, Bhaskar R. Sathe
As
functional molecules, amino acids have attracted great attention
in the field of material sciences due to their interactive sites.
New studies have shown the electrocatalytic activity capability of
amino-acid-functionalized graphene oxide (GO) toward the oxygen evolution
reaction (OER). The improved active sites and further tunable and
huge surface area after l-lysine functionalization on reduced
graphene oxide (Ly-rGO) offer significant opportunities for further
enhancement in the OER activity. Herein, the functionalization of
GO with terminal nitrogen-containing groups (l-lysine) results
in efficient and stable electrocatalytic activity for OER with a lower
overpotential of 0.33 V at 10 mA cm–2 and a lower
Tafel slope of 80 mV dec–1. Electrochemical impedance
spectroscopic of Ly-rGO also shows a lower Rct = 29.58 Ω and an excellent current stability for 5000
s at an onset potential of 1.29 V vs SCE in 0.5 M KOH. Morphological
studies based on high-resolution transmission electron microscopy
confirm that the size of Ly-rGO is ∼5 nm. X-ray photoelectron
spectroscopic analysis confirms the surface functionalization of GO
by lysine (Ly-rGO) from the binding energies of C–N, C–O,
and C–C. From this perspective, our findings emphasize the
usefulness of metal-free amino-acid-functionalized carbon-based electrocatalysts
for OER, which is an important water-splitting reaction, and demonstrates
that they may be keys toward enhancement in activities.