Dehydrated layered double hydroxides: Alcohothermal synthesis and oxygen evolution activity

Abstract

Layered double hydroxides (LDHs) are a class of two-dimensional (2D) layered materials with extensive applications and well-developed synthesizing methods in aqueous media. In this work, we introduce an alcohothermal synthesis method for fabricating NiFe-LDHs with dehydrated galleries. The proposed process involves incomplete hydrolysis of urea for the simultaneous precipitation of metal ions, with the resulting water-deficient ethanol environment leading to the formation of a dehydrated structure. The formation of a gallery-dehydrated layer structure was confirmed by X-ray diffraction (XRD), as well as by a subsequent rehydration process. The methodology introduced here is also applicable for fabricating Fe-based LDHs (NiFe-LDH and NiCoFe-LDH) nanoarrays, which cannot be produced under the same conditions in aqueous media because of the different precipitation processes involved. The LDH nanoarrays exhibit excellent electrocatalytic performance in the oxygen evolution reaction, as a result of their high intrinsic activity and unique structural features. In summary, this study not only introduces a new method for synthesizing LDH materials, but also provides a new route towards highly active and robust electrodes for electrocatalysis.