Metallenes: synthesis, properties, and applications in electrocatalysis and energy storage

Abstract

Metallenes, a newly emerging class of atomically thin metallic nanosheets, have attracted significant interest because of their abundance of catalytically active sites, tunable electronic structure, and distinctive two-dimensional shape. Advanced synthetic strategies, including liquid-phase exfoliation, template-assisted growth, and chemical reduction, enable precise control over thickness, composition, and surface chemistry, leading to physicochemical properties that surpass those of their bulk counterparts. Owing to their remarkable mechanical flexibility, electrical conductivity, and surface reactivity, metallenes have demonstrated remarkable performance in electrochemical applications. Notably, they exhibit enhanced catalytic activity and stability for CO₂ reduction, oxygen reduction, and hydrogen evolution reactions, achieving lower overpotentials and improved durability. In energy storage systems, metallenes facilitate rapid ion transport and high charge storage capacity, thereby improving the efficiency of supercapacitors and rechargeable batteries when used as active electrodes or conductive frameworks. This review critically summarizes recent advances in synthesis methodologies, structure–property relationships, and catalytic mechanisms, while outlining key challenges related to scalable production, long-term stability, and device integration. Future research directions focusing on the rational structural design of multifunctional hybrid systems are proposed to accelerate their practical deployment in next-generation energy technologies.