Layered Double Hydroxide Nanosheets with Multiple Vacancies Obtained by Dry Exfoliation as Highly Efficient Oxygen Evolution Electrocatalysts

Abstract

Layered double hydroxides (LDHs) with two-dimensional lamellar structures show excellent electrocatalytic properties. However, the catalytic activity of LDHs needs to be further improved as the large lateral size and thickness of the bulk material limit the number of exposed active sites. However, the development of efficient strategies to exfoliate bulk LDHs into stable monolayer LDH nanosheets with more exposed active sites is very challenging. On the other hand, the intrinsic activity of monolayer LDH nanosheets can be tuned by surface engineering. Herein, we have exfoliated bulk CoFe LDHs into ultrathin LDH nanosheets through Ar plasma etching, which also resulted in the formation of multiple vacancies (including O, Co, and Fe vacancies) in the ultrathin 2D nanosheets. Owing to their ultrathin 2D structure, the LDH nanosheets expose a greater number of active sites, and the multiple vacancies significantly improve the intrinsic activity in the oxygen evolution reaction (OER).

Boosting the Electrocatalytic Activity of Co3O4 Nanosheets for a Li-O2 Battery through Modulating Inner Oxygen Vacancy and Exterior Co3+/Co2+ Ratio

“…50 The oxygen vacancies in the interior facilitate the electron and Li + conductivity as well as accelerate OER process as active sites binding to O2 and Li2O2. 51 The nanosheets have more Co 3+ on the surface and more Co 2+ in the inner. Similar to spinel λ-MnO2, the Co 2+ /Co 3+ redox reaction can react with superoxide and Li2O2 to promote the ORR and OER reaction during the cycles.…”

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

“…The SEM images shown in Figure S9 (Supporting Information) confirm that the catalyst was uniformly deposited on the IO CuFeO 2 without collapsing of the macroporous structure. [45] Thus, the transmission electron microscopy (TEM) analysis suggests the successful formation of the CoFe LDH nanosheets on top of the IO CuFeO 2 photocathodes. The high-angle annular dark field (HAADF) image and EDX elemental mapping image clearly reveal the distribution of each layer (Figure 3b), illustrating the uniform CoFe LDH coating due to fast electrodeposition.…”

Ultrathin layered double hydroxide nanosheets with Ni(III) active species obtained by exfoliation for highly efficient ethanol electrooxidation

“…The Ni(III) surface states in NiAl-LDH-NSs account for ~56.5%, versus ~10.7% in the bulk NiAl-LDHs. The growing amount of surface Ni(III) species in NiAl-LDH-NSs is possibly attributed to the change of the atomic environment of the Ni atoms in the layer after exfoliation into single layer [21,35]. As the Ni(III) is really active site for Ni-based EOR electrocatalysts, thus the presence of high content of Ni(III) in the ultrathin NiAl-LDH-NSs could be significantly improve their catalytic activity in the EOR.…”