1 research outputs found
Study on the Catalytic Activity of Noble Metal Nanoparticles on Reduced Graphene Oxide for Oxygen Evolution Reactions in Lithium–Air Batteries
Among many challenges present in
Li–air batteries, one of the main reasons of low efficiency
is the high charge overpotential due to the slow oxygen evolution
reaction (OER). Here, we present systematic evaluation of Pt, Pd,
and Ru nanoparticles supported on rGO as OER electrocatalysts in Li–air
cell cathodes with LiCF<sub>3</sub>SO<sub>3</sub>–tetraÂ(ethylene
glycol) dimethyl ether (TEGDME) salt-electrolyte system. All of the
noble metals explored could lower the charge overpotentials, and among
them, Ru-rGO hybrids exhibited the most stable cycling performance
and the lowest charge overpotentials. Role of Ru nanoparticles in
boosting oxidation kinetics of the discharge products were investigated.
Apparent behavior of Ru nanoparticles was different from the conventional
electrocatalysts that lower activation barrier through electron transfer,
because the major contribution of Ru nanoparticles in lowering charge
overpotential is to control the nature of the discharge products.
Ru nanoparticles facilitated thin film-like or nanoparticulate Li<sub>2</sub>O<sub>2</sub> formation during oxygen reduction reaction (ORR),
which decomposes at lower potentials during charge, although the conventional
role as electrocatalysts during OER cannot be ruled out. Pt-and Pd-rGO
hybrids showed fluctuating potential profiles during the cycling.
Although Pt- and Pd-rGO decomposed the electrolyte after electrochemical
cycling, no electrolyte instability was observed with Ru-rGO hybrids.
This study provides the possibility of screening selective electrocatalysts
for Li–air cells while maintaining electrolyte stability