1 research outputs found
Cobalt Selenide Nanostructures: An Efficient Bifunctional Catalyst with High Current Density at Low Coverage
Electrodeposited Co<sub>7</sub>Se<sub>8</sub> nanostructures exhibiting flake-like morphology show bifunctional
catalytic activity for oxygen evolution and hydrogen evolution reaction
(OER and HER, respectively) in alkaline medium with long-term durability
(>12 h) and high Faradaic efficiency (99.62%). In addition to low
Tafel slope (32.6 mV per decade), the Co<sub>7</sub>Se<sub>8</sub> OER electrocatalyst also exhibited very low overpotential to achieve
10 mA cm<sup>–2</sup> (0.26 V) which is lower than other transition
metal chalcogenide based OER electrocatalysts reported in the literature
and significantly lower than the state-of-the-art precious metal oxides.
A low Tafel slope (59.1 mV per decade) was also obtained for the HER
catalytic activity in alkaline electrolyte. The OER catalytic activity
could be further improved by creating arrays of 3-dimensional rod-like
and tubular structures of Co<sub>7</sub>Se<sub>8</sub> through confined
electrodeposition on lithographically patterned nanoelectrodes. Such
arrays of patterned nanostructures produced exceptionally high mass
activity and gravimetric current density (∼68 000 A
g<sup>–1</sup>) compared to the planar thin films (∼220
A g<sup>–1</sup>). Such high mass activity of the catalysts
underlines reduction in usage of the active material without compromising
efficiency and their practical applicability. The catalyst layer could
be electrodeposited on different substrates, and an effect of the
substrate surface on the catalytic activity was also investigated.
The Co<sub>7</sub>Se<sub>8</sub> bifunctional catalyst enabled water
electrolysis in alkaline solution at a cell voltage of 1.6 V. The
electrodeposition works with exceptional reproducibility on any conducting
substrate and shows unprecedented catalytic performance especially
with the patterned growth of catalyst rods and tubes