One-pot synthesis of powder-form β-Ni(OH)₂ monolayer nanosheets with high electrochemical performance

In this work, β-Ni(OH)₂ monolayer nanosheets, which had been thought to be unachievable, were successfully prepared for the first time by a one-pot strategy using epoxide as precipitation agent and sodium dodecyl sulfate (SDS) as surfactant. The characterization results indicate that the formation of monolayer morphology depends on the mediation of SDS molecules. The XRD patterns demonstrate the loose and defective packing of Ni(OH)₂ layers in the SDS intercalated samples. The disappearing of vibration band of free hydroxyl groups in the FTIR spectra suggests the interlayer separation resulted by SDS. The TEM and AFM images further confirm the formation of monolayer nanosheets. It is proposed that the in situ modification of the secondary growth unit of β-Ni(OH)₂ by SDS allows its two-dimensional anisotropic growth through steric hindrance of SDS molecules. In addition, this effect allows isolation of β-Ni(OH)₂ from solvent with keeping of monolayer nanosheet state in dry powder. The electrochemical measurement results indicate that β-Ni(OH)₂ monolayer nanosheets own much higher urea electrolysis performance than their corresponding multilayer structure.