A wafer-scale 1 nm Ni(OH) nanosheet with superior electrocatalytic activity for the oxygen evolution reaction.

A wafer-scale 1.4 nm ultrathin Ni(OH) nanosheet was synthesized by ionic layer epitaxy. This free-standing Ni(OH) nanosheet was directly used to catalyze the oxygen evolution reaction (OER). At a current density of 10 mA cm, the overpotential reached 295 mV (vs. RHE) in Fe-rich 1 M NaOH. This 1.4 nm Ni(OH) nanosheet showed a very high turnover frequency of 5.47 s and a mass activity of more than 2 × 10 A g at an overpotential of 300 mV. Such a high electrocatalytic mass activity of the Ni(OH) nanosheet was more than 2 orders of magnitude higher than those of typical OER catalysts. The capability of producing wafer-scale nanometer-thick nanosheets offers a promising strategy to improve the mass efficiency of electrochemical catalysts, which is particularly valuable for preserving rare and precious catalyst materials.