Cobalt
telluride has been identified as an efficient multifunctional
electrocatalyst for oxygen and hydrogen evolution reactions and oxygen
reduction reaction in alkaline medium. Both hydrothermally synthesized
and electrodeposited, CoTe and CoTe2 show efficient electrocatalytic
activities. CoTe shows better efficiency for OER with a low Tafel
slope (43.8 mV dec–1) and lower overpotential (200
mV) at 10 mA cm–2 compared to CoTe2.
DFT studies have also been performed which revealed that CoTe showed
higher adsorption energy for intermediate −OH adsorption on
the catalyst surface, which corresponds to the catalyst activation
step. Comparison of the −OH adsorption energies (E
ads) on different catalyst surfaces with the observed
overpotential also revealed that this E
ads can be used as an appropriate descriptor for benchmarking catalytic
efficiencies. Both CoTe and CoTe2 exhibited improved OER
catalytic efficiency compared to Co3O4, confirming
the primary hypothesis that decreasing anion electronegativity enhances
catalytic efficiency by virtue of increasing lattice covalency around
the catalytically active site. The difference in OER catalytic activity
between CoTe and CoTe2 could be explained from fundamental
materials chemistry concepts by comparing their lattice structures
which showed different packing density of catalytically active Co
sites as well as varying unsaturation of Co-terminated surfaces. Band
structure calculations also corroborated such differences and could
potentially explain the difference in activity due to observed differences
in electron density distribution around the catalytically active Co
site. The cobalt telluride compositions also showed moderate HER and
ORR activity in alkaline medium, making them trifunctional catalysts
which can be used in practical devices. Both CoTe and CoTe2 showed extensive functional and compositional stability for OER,
HER, and ORR, under continuous operation in alkaline medium for over
24 h with less than 5% degradation of current density. The excellent
compositional stability of each catalyst was revealed by detailed
electrochemical measurements and surface and bulk analytical characterizations,
which confirmed that there was no catalyst leaching even with long-term
operation and no other impurity enrichment in the electrolyte.
Transition metal selenides have attracted intensive interest as cost-effective electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) because of the continuous thrust in sustainable energy conversion. In...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.