Three-Dimensional Crystalline/Amorphous Co/Co₃O₄ Core/Shell Nanosheets as Efficient Electrocatalysts for the Hydrogen Evolution Reaction

Abstract

Earth-abundant, low-cost electrocatalysts with outstanding catalytic activity in the electrochemical hydrogen evolution reaction (HER) are critical in realizing the hydrogen economy to lift our future welfare and civilization. Here we report that excellent HER activity has been achieved with three-dimensional core/shell Co/Co3O4 nanosheets composed of a metallic cobalt core and an amorphous cobalt oxide shell. A benchmark HER current density of 10 mA cm(-2) has been achieved at an overpotential of ∼90 mV in 1 M KOH. The excellent activity is enabled with the unique metal/oxide core/shell structure, which allows high electrical conductivity in the core and high catalytic activity on the shell. This finding may open a door to the design and fabrication of earth-abundant, low-cost metal oxide electrocatalysts with satisfactory hydrogen evolution reaction activities.

Crystalline/amorphous Ni/NiO core/shell nanosheets as highly active electrocatalysts for hydrogen evolution reaction

“…This indicated that oxygen vacancy alone could not guarantee the high catalytic activity. Therefore, it was very likely that the surface-defective amorphous NiO shell lowered the HER energy barrier [42].…”

Atomic-scale Pt clusters decorated on porous α-Ni(OH)2 nanowires as highly efficient electrocatalyst for hydrogen evolution reaction

“…Up to now, the platinum-based catalyst is still the best HER electrocatalyst under alkaline conditions due to the low onset overpotential, small Tafel slope and strong durability [7]. Although many non-noble-metal electrocatalysts such as Ni-based alloys [8][9][10][11][12] and Co-based nanocomposites [13][14][15] have motivated intense research on electrocatalytic HER, their poorer HER performance than Pt-based catalysts enormously restricts their practical applications. Consequently, how to enhance the HER activity of Pt-based materials in basic media is a greatly valuable but very challenging project.…”

Modifying oxide nanomaterials’ properties by hydrogenation

“…[106] Co 3 O 4 Similar to the changes induced on NiO nanosheets, hydrogenation is also shown to convert Co 3 O 4 nanosheets to Co/Co 3 O 4 crystalline/amorphous core/shell nanosheets. [107] These Figure 7. (a) Schematic illustration of the hydrogenation-induced structural change from Ni x CeO 2+x to Ni/CeO 2 on carbon nanotubes.…”

“…[107] Oxygen vacancies however, cause a poor performance. Typical microscopy images and the catalytic activity of the hydrogenated Co/ Co 3 O 4 nanosheets are shown in Fig.…”

“…9. [107] Ni Functional Oxides Prospective Article heteronanostructure. [108] And the corresponding activities in oxygen and hydrogen evolution reactions can be tuned after hydrogenation.…”