Room-temperature high-efficiency electrocatalysis in two-dimensional ultrathin amorphous Ni–Mo–O nanosheets

Abstract

Ultrathin two-dimensional (2D) materials offer great application prospects in the field of electrocatalysis due to their extremely large surface area. We synthesized 2D ultrathin amorphous Ni–Mo–O nanosheets (NSs) with a rectangular morphology and a thickness of approximately 2.1 nm by using the ion layer epitaxial (ILE) method at the water–air interface, which were used as efficient room-temperature OER electrocatalysts. By controlling the molar ratio of the precursor, we found that when the molar ratio of Ni/Mo was optimized to 2 : 1, the 2 : 1 Ni–Mo–O NSs exhibited excellent catalytic activity for the OER, and their mass activity was three orders of magnitude higher than that of the reference IrO₂ and RuO₂. The ILE method not only achieves atomic-level thickness modulation, triggering quantum confinement effects and significantly enhancing catalytic activity, but also achieves an outstanding utilization rate of raw materials. In addition, the inherent amorphous structure of ILE synthetic materials provides a high density of atomic-level defects and abundant exposure of active sites, significantly enhancing their catalytic performance. This work demonstrates that the ILE method is an ideal approach for developing high-efficiency 2D materials and opens new avenues for designing high-performance OER electrocatalysts.