The emergence of amorphous materials approaching the single-layer limit

Amorphous materials with thickness thinned down to the single-layer limit have attracted increasing interest due to their well-defined disorder and emerging unique properties, such as disorder-dominated electronic states, high-density unsaturated coordination, enhanced quantum confinement, etc. These features could enable innovative applications in electronics, photoelectronics, catalysis, and beyond. In this perspective, we provide an overview of recent advances in two-dimensional (2D) amorphous materials approaching the single-layer limit. We first introduce newly-developed key structural descriptors for these systems, including local bonding, topological disorder, and chemical composition. Next, we highlight fabrication breakthroughs across diverse material classes, such as amorphous carbon, oxides/hydroxides, metals, transition metal dichalcogenides (TMDCs), and metal/covalent-organic frameworks (MOFs/COFs). The resulting properties, spanning electrical/electrocatalytic properties, mechanical toughness, photoelectric response, and topological electronic states, are subsequently discussed. Finally, we outline current challenges and future opportunities in this rapidly evolving field.